Invoke rpmh_flush for non OSI targets

Currently rpmh ctrlr dirty flag is set for all cases regardless of data is really changed or not. Add changes to update dirty flag when data is changed to newer values. Update dirty flag everytime when data in batch cache is updated since rpmh_flush() may get invoked from any CPU instead of only last CPU going to low power mode.

Also move dirty flag updates to happen from within cache_lock and remove unnecessary INIT_LIST_HEAD() call and a default case from switch.

Fixes 600513dfeef3 ("drivers: qcom: rpmh: cache sleep/wake state requests")

Signed-off-by Maulik Shah <[email protected]>

Reviewed-by Srinivas Rao L <[email protected]>

Reviewed-by Evan Green <[email protected]>

---
 drivers/soc/qcom/rpmh.c | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

Hi,

Quoted 9 lines · Maulik Shah

Currently rpmh ctrlr dirty flag is set for all cases regardless of data is really changed or not. Add changes to update dirty flag when data is changed to newer values. Update dirty flag everytime when data in batch cache is updated since rpmh_flush() may get invoked from any CPU instead of only last CPU going to low power mode.

Also move dirty flag updates to happen from within cache_lock and remove unnecessary INIT_LIST_HEAD() call and a default case from switch.

Quoted 7 lines

Fixes 600513dfeef3 ("drivers: qcom: rpmh: cache sleep/wake state requests")

Signed-off-by Maulik Shah <[email protected]>

Reviewed-by Srinivas Rao L <[email protected]>

Reviewed-by Evan Green <[email protected]>

---
 drivers/soc/qcom/rpmh.c | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

Reviewed-by Douglas Anderson <[email protected]>

TCSes have previously programmed data when rpmh_flush is called. This can cause old data to trigger along with newly flushed.

Fix this by cleaning SLEEP and WAKE TCSes before new data is flushed.

With this there is no need to invoke rpmh_rsc_invalidate() call from rpmh_invalidate().

Simplify rpmh_invalidate() by moving invalidate_batch() inside.

Fixes 600513dfeef3 ("drivers: qcom: rpmh: cache sleep/wake state requests")

Signed-off-by Maulik Shah <[email protected]>

---
 drivers/soc/qcom/rpmh.c | 36 +++++++++++++++---------------------
 1 file changed, 15 insertions(+), 21 deletions(-)

drivers/soc/qcom/rpmh.c +0 -13

index 03630ae..5bed8f4 100644
@@ -317,19 +317,6 @@ static int flush_batch(struct rpmh_ctrlr *ctrlr)
        return ret;
 }
 
-static void invalidate_batch(struct rpmh_ctrlr *ctrlr)
-{
-       struct batch_cache_req *req, *tmp;
-       unsigned long flags;
-
-       spin_lock_irqsave(&ctrlr->cache_lock, flags);
-       list_for_each_entry_safe(req, tmp, &ctrlr->batch_cache, list)
-               kfree(req);
-       INIT_LIST_HEAD(&ctrlr->batch_cache);
-       ctrlr->dirty = true;
-       spin_unlock_irqrestore(&ctrlr->cache_lock, flags);
-}
-
 /**
  * rpmh_write_batch: Write multiple sets of RPMH commands and wait for the
  * batch to finish.

Hi,

Quoted 41 lines · Maulik Shah

TCSes have previously programmed data when rpmh_flush is called. This can cause old data to trigger along with newly flushed.

Fix this by cleaning SLEEP and WAKE TCSes before new data is flushed.

With this there is no need to invoke rpmh_rsc_invalidate() call from rpmh_invalidate().

Simplify rpmh_invalidate() by moving invalidate_batch() inside.

Fixes 600513dfeef3 ("drivers: qcom: rpmh: cache sleep/wake state requests")

Signed-off-by Maulik Shah <[email protected]>

---
 drivers/soc/qcom/rpmh.c | 36 +++++++++++++++---------------------
 1 file changed, 15 insertions(+), 21 deletions(-)

drivers/soc/qcom/rpmh.c +0 -13

index 03630ae..5bed8f4 100644
@@ -317,19 +317,6 @@ static int flush_batch(struct rpmh_ctrlr *ctrlr)
        return ret;
 }
 
-static void invalidate_batch(struct rpmh_ctrlr *ctrlr)
-{
-       struct batch_cache_req *req, *tmp;
-       unsigned long flags;
-
-       spin_lock_irqsave(&ctrlr->cache_lock, flags);
-       list_for_each_entry_safe(req, tmp, &ctrlr->batch_cache, list)
-               kfree(req);
-       INIT_LIST_HEAD(&ctrlr->batch_cache);
-       ctrlr->dirty = true;
-       spin_unlock_irqrestore(&ctrlr->cache_lock, flags);
-}
-
 /**
  * rpmh_write_batch: Write multiple sets of RPMH commands and wait for the
  * batch to finish.

drivers/soc/qcom/rpmh.c int rpmh_flush(struct rpmh_ctrlr *ctrlr) · line 461

Quoted 8 lines

drivers/soc/qcom/rpmh.c +5 -0

@@ -467,6 +454,11 @@ int rpmh_flush(struct rpmh_ctrlr *ctrlr)
                return 0;
        }
 
+       /* Invalidate the TCSes first to avoid stale data */
+       do {
+               ret = rpmh_rsc_invalidate(ctrlr_to_drv(ctrlr));
+       } while (ret == -EAGAIN);
+

You forgot to actually check the return value.

if (ret)
return ret;

drivers/soc/qcom/rpmh.c int rpmh_flush(struct rpmh_ctrlr *ctrlr) · line 498

Quoted 10 lines

drivers/soc/qcom/rpmh.c +1 -1

        /* First flush the cached batch requests */
        ret = flush_batch(ctrlr);
        if (ret)

@@ -503,19 +495,21 @@ int rpmh_flush(struct rpmh_ctrlr *ctrlr)
  *
  * @dev: The device making the request
  *
- * Invalidate the sleep and active values in the TCS blocks.
+ * Invalidate the sleep and wake values in batch_cache.

Thanks for updating this. It was on my todo list. Can you also update the function description, which still says "Invalidate all sleep and active sets sets." While you're at it, remove the double "sets".

Add changes to invoke rpmh flush() from within cache_lock when the data in cache is dirty.

Introduce two new APIs for this. Clients can use rpmh_start_transaction() before any rpmh transaction once done invoke rpmh_end_transaction() which internally invokes rpmh_flush() if the caches has become dirty.

Add support to control this with flush_dirty flag.

Signed-off-by Maulik Shah <[email protected]>

Reviewed-by Srinivas Rao L <[email protected]>

---
 drivers/soc/qcom/rpmh-internal.h |  4 +++
 drivers/soc/qcom/rpmh-rsc.c      |  6 +++-
 drivers/soc/qcom/rpmh.c          | 64 ++++++++++++++++++++++++++++++++--------
 include/soc/qcom/rpmh.h          | 10 +++++++
 4 files changed, 71 insertions(+), 13 deletions(-)

drivers/soc/qcom/rpmh-internal.h +4 -0

index 6eec32b..d36be3d 100644
@@ -70,13 +70,17 @@ struct rpmh_request {
  *
  * @cache: the list of cached requests
  * @cache_lock: synchronize access to the cache data
+ * @active_clients: count of rpmh transaction in progress
  * @dirty: was the cache updated since flush
+ * @flush_dirty: if the dirty cache need immediate flush
  * @batch_cache: Cache sleep and wake requests sent as batch
  */
 struct rpmh_ctrlr {
        struct list_head cache;
        spinlock_t cache_lock;
+       u32 active_clients;
        bool dirty;
+       bool flush_dirty;
        struct list_head batch_cache;
 };
 

drivers/soc/qcom/rpmh-rsc.c +2 -0

index e278fc1..b6391e1 100644
@@ -61,6 +61,8 @@
 #define CMD_STATUS_ISSUED              BIT(8)
 #define CMD_STATUS_COMPL               BIT(16)
 
+#define FLUSH_DIRTY                    1
+
 static u32 read_tcs_reg(struct rsc_drv *drv, int reg, int tcs_id, int cmd_id)
 {
        return readl_relaxed(drv->tcs_base + reg + RSC_DRV_TCS_OFFSET * tcs_id +

@@ -670,13 +672,15 @@ static int rpmh_rsc_probe(struct platform_device *pdev)
        INIT_LIST_HEAD(&drv->client.cache);
        INIT_LIST_HEAD(&drv->client.batch_cache);
 

drivers/soc/qcom/rpmh-rsc.c +0 -0

        { }
 };
 

drivers/soc/qcom/rpmh.c +5 -3

index 5bed8f4..9d40209 100644
@@ -297,12 +297,10 @@ static int flush_batch(struct rpmh_ctrlr *ctrlr)
 {
        struct batch_cache_req *req;
        const struct rpmh_request *rpm_msg;
-       unsigned long flags;
        int ret = 0;
        int i;
 
        /* Send Sleep/Wake requests to the controller, expect no response */
-       spin_lock_irqsave(&ctrlr->cache_lock, flags);
        list_for_each_entry(req, &ctrlr->batch_cache, list) {
                for (i = 0; i < req->count; i++) {
                        rpm_msg = req->rpm_msgs + i;

@@ -312,7 +310,6 @@ static int flush_batch(struct rpmh_ctrlr *ctrlr)
                                break;
                }
        }
-       spin_unlock_irqrestore(&ctrlr->cache_lock, flags);
 
        return ret;
 }

@@ -433,16 +430,63 @@ static int send_single(struct rpmh_ctrlr *ctrlr, enum rpmh_state state,
 }
 
 /**
+ * rpmh_start_transaction: Indicates start of rpmh transactions, this
+ * must be ended by invoking rpmh_end_transaction().
+ *
+ * @dev: the device making the request
+ */

drivers/soc/qcom/rpmh.c +12 -0

+       spin_unlock_irqrestore(&ctrlr->cache_lock, flags);
+}
+EXPORT_SYMBOL(rpmh_start_transaction);
+
+/**
+ * rpmh_end_transaction: Indicates end of rpmh transactions. All dirty data
+ * in cache can be flushed immediately when ctrlr->flush_dirty is set
+ *
+ * @dev: the device making the request
+ *
+ * Return: 0 on success, error number otherwise.
+ */

drivers/soc/qcom/rpmh.c +11 -9

+
+       spin_unlock_irqrestore(&ctrlr->cache_lock, flags);
+
+       return ret;
+}
+EXPORT_SYMBOL(rpmh_end_transaction);
+
+/**
  * rpmh_flush: Flushes the buffered active and sleep sets to TCS
  *
  * @ctrlr: controller making request to flush cached data
  *
- * Return: -EBUSY if the controller is busy, probably waiting on a response
- * to a RPMH request sent earlier.
+ * Return: 0 on success, error number otherwise.
  *
- * This function is always called from the sleep code from the last CPU
- * that is powering down the entire system. Since no other RPMH API would be
- * executing at this time, it is safe to run lockless.
+ * This function can either be called from sleep code on the last CPU
+ * (thus no spinlock needed) or with the ctrlr->cache_lock already held.
  */
 int rpmh_flush(struct rpmh_ctrlr *ctrlr)
 {

@@ -464,10 +508,6 @@ int rpmh_flush(struct rpmh_ctrlr *ctrlr)
        if (ret)
                return ret;
 
-       /*
-        * Nobody else should be calling this function other than system PM,
-        * hence we can run without locks.
-        */
        list_for_each_entry(p, &ctrlr->cache, list) {
                if (!is_req_valid(p)) {
                        pr_debug("%s: skipping RPMH req: a:%#x s:%#x w:%#x",

include/soc/qcom/rpmh.h +4 -0

index f9ec353..85e1ab2 100644
@@ -22,6 +22,10 @@ int rpmh_write_batch(const struct device *dev, enum rpmh_state state,
 
 int rpmh_invalidate(const struct device *dev);
 
+void rpmh_start_transaction(const struct device *dev);
+
+int rpmh_end_transaction(const struct device *dev);
+
 #else
 
 static inline int rpmh_write(const struct device *dev, enum rpmh_state state,

Hi,

Quoted 9 lines · Maulik Shah

Add changes to invoke rpmh flush() from within cache_lock when the data in cache is dirty.

Introduce two new APIs for this. Clients can use rpmh_start_transaction() before any rpmh transaction once done invoke rpmh_end_transaction() which internally invokes rpmh_flush() if the caches has become dirty.

Add support to control this with flush_dirty flag.

Quoted 8 lines

Signed-off-by Maulik Shah <[email protected]>

Reviewed-by Srinivas Rao L <[email protected]>

---
 drivers/soc/qcom/rpmh-internal.h |  4 +++
 drivers/soc/qcom/rpmh-rsc.c      |  6 +++-
 drivers/soc/qcom/rpmh.c          | 64 ++++++++++++++++++++++++++++++++--------
 include/soc/qcom/rpmh.h          | 10 +++++++
 4 files changed, 71 insertions(+), 13 deletions(-)

As mentioned previously but not addressed [3], I believe your series breaks things if there are zero ACTIVE TCSs and you're using the immediate-flush solution. Specifically any attempt to set something's "active" state will clobber the sleep/wake. I believe this is hard to fix, especially if you want rpmh_write_async() to work properly and need to be robust to the last man going down while rpmh_write_async() is running but hasn't finished. My suggestion was to consider it to be an error at probe time for now.

Actually, though, I'd be super surprised if the "active == 0" case works anyway. Aside from subtle problems of not handling -EAGAIN (see another previous message that you didn't respond to [2]), I think you'll also get failures because you never enable interrupts in RSC_DRV_IRQ_ENABLE for anything other than the ACTIVE_TCS. Thus you'll never get interrupts saying when your transactions on the borrowed "wake" TCS finish.

Speaking of previous emails that you didn't respond to, I think you still have these action items:

* Document that rpmh_write(active) and rpmh_write_async(active) also updates wake state. [1]

* Change is_req_valid() to still return true if (sleep == wake), or keep track of "active" and return true if (sleep != wake || wake != active). [1]

* Document that for batch a write to active doesn't update wake. [1]

Quoted 47 lines

drivers/soc/qcom/rpmh-internal.h +4 -0

index 6eec32b..d36be3d 100644
@@ -70,13 +70,17 @@ struct rpmh_request {
  *
  * @cache: the list of cached requests
  * @cache_lock: synchronize access to the cache data
+ * @active_clients: count of rpmh transaction in progress
  * @dirty: was the cache updated since flush
+ * @flush_dirty: if the dirty cache need immediate flush
  * @batch_cache: Cache sleep and wake requests sent as batch
  */
 struct rpmh_ctrlr {
        struct list_head cache;
        spinlock_t cache_lock;
+       u32 active_clients;
        bool dirty;
+       bool flush_dirty;
        struct list_head batch_cache;
 };
 

drivers/soc/qcom/rpmh-rsc.c +4 -0

index e278fc1..b6391e1 100644
@@ -61,6 +61,8 @@
 #define CMD_STATUS_ISSUED              BIT(8)
 #define CMD_STATUS_COMPL               BIT(16)
 
+#define FLUSH_DIRTY                    1
+
 static u32 read_tcs_reg(struct rsc_drv *drv, int reg, int tcs_id, int cmd_id)
 {
        return readl_relaxed(drv->tcs_base + reg + RSC_DRV_TCS_OFFSET * tcs_id +

@@ -670,13 +672,15 @@ static int rpmh_rsc_probe(struct platform_device *pdev)
        INIT_LIST_HEAD(&drv->client.cache);
        INIT_LIST_HEAD(&drv->client.batch_cache);
 
+       drv->client.flush_dirty = device_get_match_data(&pdev->dev);
+
        dev_set_drvdata(&pdev->dev, drv);
 
        return devm_of_platform_populate(&pdev->dev);
 }
 

drivers/soc/qcom/rpmh-rsc.c static int rpmh_rsc_probe(struct platform_device *pdev) · line 683

Quoted 3 lines

drivers/soc/qcom/rpmh-rsc.c +1 -1

 static const struct of_device_id rpmh_drv_match[] = {
-       { .compatible = "qcom,rpmh-rsc", },
+       { .compatible = "qcom,rpmh-rsc", .data = (void *)FLUSH_DIRTY },

Ick. This is just confusing. IMO better to set 'drv->client.flush_dirty = true' directly in probe with a comment saying that it could be removed if we had OSI.

...and while you're at it, why not fire off a separate patch (not in your series) adding the stub to 'include/linux/psci.h'. Then when we revisit this in a year it'll be there and it'll be super easy to set the value properly.

Quoted 38 lines

drivers/soc/qcom/rpmh-rsc.c +0 -0

        { }
 };
 

drivers/soc/qcom/rpmh.c +5 -3

index 5bed8f4..9d40209 100644
@@ -297,12 +297,10 @@ static int flush_batch(struct rpmh_ctrlr *ctrlr)
 {
        struct batch_cache_req *req;
        const struct rpmh_request *rpm_msg;
-       unsigned long flags;
        int ret = 0;
        int i;
 
        /* Send Sleep/Wake requests to the controller, expect no response */
-       spin_lock_irqsave(&ctrlr->cache_lock, flags);
        list_for_each_entry(req, &ctrlr->batch_cache, list) {
                for (i = 0; i < req->count; i++) {
                        rpm_msg = req->rpm_msgs + i;

@@ -312,7 +310,6 @@ static int flush_batch(struct rpmh_ctrlr *ctrlr)
                                break;
                }
        }
-       spin_unlock_irqrestore(&ctrlr->cache_lock, flags);
 
        return ret;
 }

@@ -433,16 +430,63 @@ static int send_single(struct rpmh_ctrlr *ctrlr, enum rpmh_state state,
 }
 
 /**
+ * rpmh_start_transaction: Indicates start of rpmh transactions, this
+ * must be ended by invoking rpmh_end_transaction().
+ *
+ * @dev: the device making the request
+ */

drivers/soc/qcom/rpmh.c static int send_single(struct rpmh_ctrlr *ctrlr, enum rpmh_state state, · line 447

Quoted 10 lines

drivers/soc/qcom/rpmh.c +10 -0

+void rpmh_start_transaction(const struct device *dev)
+{
+       struct rpmh_ctrlr *ctrlr = get_rpmh_ctrlr(dev);
+       unsigned long flags;
+
+       if (!ctrlr->flush_dirty)
+               return;
+
+       spin_lock_irqsave(&ctrlr->cache_lock, flags);
+       ctrlr->active_clients++;

Wouldn't hurt to have something like:

/*
* Detect likely leak; we shouldn't have 1000
* people making in-flight changes at the same time. */
WARN_ON(ctrlr->active_clients > 1000)

Quoted 17 lines

drivers/soc/qcom/rpmh.c +15 -0

+       spin_unlock_irqrestore(&ctrlr->cache_lock, flags);
+}
+EXPORT_SYMBOL(rpmh_start_transaction);
+
+/**
+ * rpmh_end_transaction: Indicates end of rpmh transactions. All dirty data
+ * in cache can be flushed immediately when ctrlr->flush_dirty is set
+ *
+ * @dev: the device making the request
+ *
+ * Return: 0 on success, error number otherwise.
+ */
+int rpmh_end_transaction(const struct device *dev)
+{
+       struct rpmh_ctrlr *ctrlr = get_rpmh_ctrlr(dev);

drivers/soc/qcom/rpmh.c static int send_single(struct rpmh_ctrlr *ctrlr, enum rpmh_state state, · line 469

Quoted 7 lines

drivers/soc/qcom/rpmh.c +7 -0

+       unsigned long flags;
+       int ret = 0;
+
+       if (!ctrlr->flush_dirty)
+               return ret;
+
+       spin_lock_irqsave(&ctrlr->cache_lock, flags);

WARN_ON(!active_clients);

drivers/soc/qcom/rpmh.c static int send_single(struct rpmh_ctrlr *ctrlr, enum rpmh_state state, · line 473

Quoted 6 lines

drivers/soc/qcom/rpmh.c +4 -0

+
+       ctrlr->active_clients--;
+       if (ctrlr->dirty && !ctrlr->active_clients)
+               ret = rpmh_flush(ctrlr);

As mentioned previously [2], I don't think it's valid to call rpmh_flush() with interrupts disabled. Specifically (as of your previous patch) rpmh_flush now loops if rpmh_rsc_invalidate() returns -EAGAIN. I believe that the caller needs to enable interrupts for a little bit before trying again. If the caller doesn't need to enable interrupts for a little bit before trying again then why was -EAGAIN even returned? tcs_invalidate() could have just looped itself and all the code would be much simpler.

Quoted 51 lines

drivers/soc/qcom/rpmh.c +11 -9

+
+       spin_unlock_irqrestore(&ctrlr->cache_lock, flags);
+
+       return ret;
+}
+EXPORT_SYMBOL(rpmh_end_transaction);
+
+/**
  * rpmh_flush: Flushes the buffered active and sleep sets to TCS
  *
  * @ctrlr: controller making request to flush cached data
  *
- * Return: -EBUSY if the controller is busy, probably waiting on a response
- * to a RPMH request sent earlier.
+ * Return: 0 on success, error number otherwise.
  *
- * This function is always called from the sleep code from the last CPU
- * that is powering down the entire system. Since no other RPMH API would be
- * executing at this time, it is safe to run lockless.
+ * This function can either be called from sleep code on the last CPU
+ * (thus no spinlock needed) or with the ctrlr->cache_lock already held.
  */
 int rpmh_flush(struct rpmh_ctrlr *ctrlr)
 {

@@ -464,10 +508,6 @@ int rpmh_flush(struct rpmh_ctrlr *ctrlr)
        if (ret)
                return ret;
 
-       /*
-        * Nobody else should be calling this function other than system PM,
-        * hence we can run without locks.
-        */
        list_for_each_entry(p, &ctrlr->cache, list) {
                if (!is_req_valid(p)) {
                        pr_debug("%s: skipping RPMH req: a:%#x s:%#x w:%#x",

include/soc/qcom/rpmh.h +4 -0

index f9ec353..85e1ab2 100644
@@ -22,6 +22,10 @@ int rpmh_write_batch(const struct device *dev, enum rpmh_state state,
 
 int rpmh_invalidate(const struct device *dev);
 
+void rpmh_start_transaction(const struct device *dev);
+
+int rpmh_end_transaction(const struct device *dev);
+
 #else
 

include/soc/qcom/rpmh.h static inline int rpmh_write_batch(const struct device *dev, · line 49

Quoted 7 lines

include/soc/qcom/rpmh.h +2 -0

 static inline int rpmh_write(const struct device *dev, enum rpmh_state state,

@@ -41,6 +45,12 @@ static inline int rpmh_write_batch(const struct device *dev,
 static inline int rpmh_invalidate(const struct device *dev)
 { return -ENODEV; }
 
+void rpmh_start_transaction(const struct device *dev)
+{ return -ENODEV; }

Unexpected return from void function.

Quoted 6 lines

include/soc/qcom/rpmh.h +4 -0

+
+int rpmh_end_transaction(const struct device *dev)
+{ return -ENODEV; }
+
 #endif /* CONFIG_QCOM_RPMH */
 

include/soc/qcom/rpmh.h static inline int rpmh_write_batch(const struct device *dev, · line 56

Quoted 1 line

include/soc/qcom/rpmh.h +0 -0

 #endif /* __SOC_QCOM_RPMH_H__ */

[1] https://lore.kernel.org/r/CAD=FV=VzNnRdDN5uPYskJ6kQHq2bAi2ysEqt0=taagdd_qZb-g@mail.gmail.com
[2] https://lore.kernel.org/r/CAD=FV=UYpO2rSOoF-OdZd3jKfSZGKnpQJPoiE5fzH+u1uafS6g@mail.gmail.com
[3] https://lore.kernel.org/r/CAD=FV=VNaqwiti+UB8fLgjF5r2CD2xeF_p7qHS-_yXqf+ZDrBg@mail.gmail.com

-Doug

Quoted 29 lines · Doug Anderson

Hi,

Quoted 9 lines · Maulik Shah

Add changes to invoke rpmh flush() from within cache_lock when the data in cache is dirty.

Introduce two new APIs for this. Clients can use rpmh_start_transaction() before any rpmh transaction once done invoke rpmh_end_transaction() which internally invokes rpmh_flush() if the caches has become dirty.

Add support to control this with flush_dirty flag.

Quoted 8 lines

Signed-off-by Maulik Shah <[email protected]>

Reviewed-by Srinivas Rao L <[email protected]>

---
 drivers/soc/qcom/rpmh-internal.h |  4 +++
 drivers/soc/qcom/rpmh-rsc.c      |  6 +++-
 drivers/soc/qcom/rpmh.c          | 64 ++++++++++++++++++++++++++++++++--------
 include/soc/qcom/rpmh.h          | 10 +++++++
 4 files changed, 71 insertions(+), 13 deletions(-)

As mentioned previously but not addressed [3], I believe your series breaks things if there are zero ACTIVE TCSs and you're using the immediate-flush solution. Specifically any attempt to set something's "active" state will clobber the sleep/wake. I believe this is hard to fix, especially if you want rpmh_write_async() to work properly and need to be robust to the last man going down while rpmh_write_async() is running but hasn't finished. My suggestion was to consider it to be an error at probe time for now.

Quoted 7 lines

Actually, though, I'd be super surprised if the "active == 0" case works anyway. Aside from subtle problems of not handling -EAGAIN (see another previous message that you didn't respond to [2]), I think you'll also get failures because you never enable interrupts in RSC_DRV_IRQ_ENABLE for anything other than the ACTIVE_TCS. Thus you'll never get interrupts saying when your transactions on the borrowed "wake" TCS finish.

No, it shouldn’t effect even with "non-OSI-mode + 0 ACTIVE TCS"

i just replied on v9, pasting same on v13 as well.

After taking your suggestion to do rpmh start/end transaction() in v13, rpmh_end_transaction() invokes rpmh_flush() only for the last client and by this time expecting all of rpmh_write() and rpmh_write_batch() will be already “finished” as client first waits for them to finish and then only invokes end.

So driver is good to handle rpmh_write() and rpmh_write_batch() calls.

Regarding rpmh_write_async() call, which is a fire-n-forget request from SW and client driver may immediately invoke rpmh_end_transaction() after this.

this case is also handled properly…
Lets again take an example for understanding this..

1. Client invokes rpmh_write_async() to send ACTIVE cmds for targets which has zero ACTIVE TCS

Rpmh driver Re-purposes one of SLEEP/WAKE TCS to use as ACTIVE, internally this also sets drv->tcs_in_use to true for respective SLEEP/WAKE TCS.

2. Client now without waiting for above to finish, goes ahead and invokes rpmh_end_transaction()
which calls rpmh_flush() (in case cache become dirty)

Now if re-purposed TCS is still in use in HW (transaction in progress), we still have drv->tcs_in_use set. So the rpmh_rsc_invalidate() (invoked from rpmh_flush()) will keep on returning -EAGAIN until that TCS becomes free to use and then goes ahead to finish its job.

Quoted 24 lines

Quoted 24 lines

drivers/soc/qcom/rpmh-rsc.c +4 -0

index e278fc1..b6391e1 100644
@@ -61,6 +61,8 @@
 #define CMD_STATUS_ISSUED              BIT(8)
 #define CMD_STATUS_COMPL               BIT(16)
 
+#define FLUSH_DIRTY                    1
+
 static u32 read_tcs_reg(struct rsc_drv *drv, int reg, int tcs_id, int cmd_id)
 {
        return readl_relaxed(drv->tcs_base + reg + RSC_DRV_TCS_OFFSET * tcs_id +

@@ -670,13 +672,15 @@ static int rpmh_rsc_probe(struct platform_device *pdev)
        INIT_LIST_HEAD(&drv->client.cache);
        INIT_LIST_HEAD(&drv->client.batch_cache);
 
+       drv->client.flush_dirty = device_get_match_data(&pdev->dev);
+
        dev_set_drvdata(&pdev->dev, drv);
 
        return devm_of_platform_populate(&pdev->dev);
 }
 

Quoted 6 lines

drivers/soc/qcom/rpmh-rsc.c static int rpmh_rsc_probe(struct platform_device *pdev) · line 683

Quoted 3 lines

drivers/soc/qcom/rpmh-rsc.c +1 -1

 static const struct of_device_id rpmh_drv_match[] = {
-       { .compatible = "qcom,rpmh-rsc", },
+       { .compatible = "qcom,rpmh-rsc", .data = (void *)FLUSH_DIRTY },

Ick. This is just confusing. IMO better to set 'drv->client.flush_dirty = true' directly in probe with a comment saying that it could be removed if we had OSI.

Done.
i will keep this bit earlier in probe with commet, so later if we detect rsc to be in hierarchy from [1], we can override this to be 0 within rpmh_probe_power_domain().

[1] https://patchwork.kernel.org/patch/11391229/

Quoted 4 lines

...and while you're at it, why not fire off a separate patch (not in your series) adding the stub to 'include/linux/psci.h'. Then when we revisit this in a year it'll be there and it'll be super easy to set the value properly.

With above approch to set it in probe accordingly PSCI change won't be required.

it will be simple, cleaner and without any resistance from PSCI perspective.

Quoted 50 lines

Quoted 38 lines

drivers/soc/qcom/rpmh-rsc.c +0 -0

        { }
 };
 

drivers/soc/qcom/rpmh.c +5 -3

index 5bed8f4..9d40209 100644
@@ -297,12 +297,10 @@ static int flush_batch(struct rpmh_ctrlr *ctrlr)
 {
        struct batch_cache_req *req;
        const struct rpmh_request *rpm_msg;
-       unsigned long flags;
        int ret = 0;
        int i;
 
        /* Send Sleep/Wake requests to the controller, expect no response */
-       spin_lock_irqsave(&ctrlr->cache_lock, flags);
        list_for_each_entry(req, &ctrlr->batch_cache, list) {
                for (i = 0; i < req->count; i++) {
                        rpm_msg = req->rpm_msgs + i;

@@ -312,7 +310,6 @@ static int flush_batch(struct rpmh_ctrlr *ctrlr)
                                break;
                }
        }
-       spin_unlock_irqrestore(&ctrlr->cache_lock, flags);
 
        return ret;
 }

@@ -433,16 +430,63 @@ static int send_single(struct rpmh_ctrlr *ctrlr, enum rpmh_state state,
 }
 
 /**
+ * rpmh_start_transaction: Indicates start of rpmh transactions, this
+ * must be ended by invoking rpmh_end_transaction().
+ *
+ * @dev: the device making the request
+ */

drivers/soc/qcom/rpmh.c static int send_single(struct rpmh_ctrlr *ctrlr, enum rpmh_state state, · line 447

Quoted 10 lines

drivers/soc/qcom/rpmh.c +10 -0

+void rpmh_start_transaction(const struct device *dev)
+{
+       struct rpmh_ctrlr *ctrlr = get_rpmh_ctrlr(dev);
+       unsigned long flags;
+
+       if (!ctrlr->flush_dirty)
+               return;
+
+       spin_lock_irqsave(&ctrlr->cache_lock, flags);
+       ctrlr->active_clients++;

Wouldn't hurt to have something like:

Quoted 5 lines

/*
* Detect likely leak; we shouldn't have 1000
* people making in-flight changes at the same time. */
WARN_ON(ctrlr->active_clients > 1000)

Not necessary change.

Quoted 15 lines

Quoted 15 lines

drivers/soc/qcom/rpmh.c +15 -0

+       spin_unlock_irqrestore(&ctrlr->cache_lock, flags);
+}
+EXPORT_SYMBOL(rpmh_start_transaction);
+
+/**
+ * rpmh_end_transaction: Indicates end of rpmh transactions. All dirty data
+ * in cache can be flushed immediately when ctrlr->flush_dirty is set
+ *
+ * @dev: the device making the request
+ *
+ * Return: 0 on success, error number otherwise.
+ */
+int rpmh_end_transaction(const struct device *dev)
+{
+       struct rpmh_ctrlr *ctrlr = get_rpmh_ctrlr(dev);

Quoted 8 lines

drivers/soc/qcom/rpmh.c static int send_single(struct rpmh_ctrlr *ctrlr, enum rpmh_state state, · line 469

Quoted 7 lines

drivers/soc/qcom/rpmh.c +7 -0

+       unsigned long flags;
+       int ret = 0;
+
+       if (!ctrlr->flush_dirty)
+               return ret;
+
+       spin_lock_irqsave(&ctrlr->cache_lock, flags);

WARN_ON(!active_clients);

Why? when active_clients become zero, we want to finally call rpmh_flush(), i don't see a reason to warn and then flush.

Or do you want to make a check if client really called rpmh_start_transaction() first before calling rpmh_end_transaction() then when we do ctrlr->active_clients--;

it shouldn't go to negative value at the end. in that case let me know, i will make those changes.

Hi,

Quoted 40 lines · Maulik Shah

Quoted 29 lines · Doug Anderson

Hi,

Quoted 9 lines · Maulik Shah

Add changes to invoke rpmh flush() from within cache_lock when the data in cache is dirty.

Introduce two new APIs for this. Clients can use rpmh_start_transaction() before any rpmh transaction once done invoke rpmh_end_transaction() which internally invokes rpmh_flush() if the caches has become dirty.

Add support to control this with flush_dirty flag.

Quoted 8 lines

Signed-off-by Maulik Shah <[email protected]>

Reviewed-by Srinivas Rao L <[email protected]>

---
 drivers/soc/qcom/rpmh-internal.h |  4 +++
 drivers/soc/qcom/rpmh-rsc.c      |  6 +++-
 drivers/soc/qcom/rpmh.c          | 64 ++++++++++++++++++++++++++++++++--------
 include/soc/qcom/rpmh.h          | 10 +++++++
 4 files changed, 71 insertions(+), 13 deletions(-)

As mentioned previously but not addressed [3], I believe your series breaks things if there are zero ACTIVE TCSs and you're using the immediate-flush solution. Specifically any attempt to set something's "active" state will clobber the sleep/wake. I believe this is hard to fix, especially if you want rpmh_write_async() to work properly and need to be robust to the last man going down while rpmh_write_async() is running but hasn't finished. My suggestion was to consider it to be an error at probe time for now.

Quoted 7 lines

Actually, though, I'd be super surprised if the "active == 0" case works anyway. Aside from subtle problems of not handling -EAGAIN (see another previous message that you didn't respond to [2]), I think you'll also get failures because you never enable interrupts in RSC_DRV_IRQ_ENABLE for anything other than the ACTIVE_TCS. Thus you'll never get interrupts saying when your transactions on the borrowed "wake" TCS finish.

No, it shouldn’t effect even with "non-OSI-mode + 0 ACTIVE TCS"

Quoted 8 lines

i just replied on v9, pasting same on v13 as well.

After taking your suggestion to do rpmh start/end transaction() in v13, rpmh_end_transaction() invokes rpmh_flush() only for the last client and by this time expecting all of rpmh_write() and rpmh_write_batch() will be already “finished” as client first waits for them to finish and then only invokes end.

So driver is good to handle rpmh_write() and rpmh_write_batch() calls.

Ah, right. In the previous version of the patch it was a problem because you flushed in cache_rpm_request() and then clobbered it right away in __rpmh_write() when you did rpmh_rsc_send_data(). With v13 that is not the case anymore. So this case should be OK.

Quoted 6 lines

Regarding rpmh_write_async() call, which is a fire-n-forget request from SW and client driver may immediately invoke rpmh_end_transaction() after this.

this case is also handled properly…
Lets again take an example for understanding this..

Quoted 7 lines

1. Client invokes rpmh_write_async() to send ACTIVE cmds for targets which has zero ACTIVE TCS

Rpmh driver Re-purposes one of SLEEP/WAKE TCS to use as ACTIVE, internally this also sets drv->tcs_in_use to true for respective SLEEP/WAKE TCS.

2. Client now without waiting for above to finish, goes ahead and invokes rpmh_end_transaction()
which calls rpmh_flush() (in case cache become dirty)

I guess we'd have to confirm that there's no way for the cache to _not_ become dirty but you do an "active" transaction. Let's imagine this case:

start transaction rpmh_write(RPMH_ACTIVE_ONLY_STATE, addr=0x10, data=0x99); rpmh_write(RPMH_SLEEP_STATE, addr=0x10, data=0x11); rpmh_write(RPMH_WAKE_ONLY_STATE, addr=0x10, data=0x99); end transaction

start transaction rpmh_write(RPMH_ACTIVE_ONLY_STATE, addr=0x10, data=0x99); rpmh_write(RPMH_SLEEP_STATE, addr=0x10, data=0x11); rpmh_write(RPMH_WAKE_ONLY_STATE, addr=0x10, data=0x99); end transaction

In other words the client does the same sequence twice in a row with no change in data. After the first set I think you'd be fine. ...but after the second set you'll be in trouble. That's because none of the calls in the second set would cause the "dirty" to be set. ...but for "active only" calls we don't have any sort of cache--we just fire it off. When we fire off the active only we'll clobber the sleep/wake TCS. ...and then nothing will write them again because the cache isn't dirty.

Quoted 4 lines

Now if re-purposed TCS is still in use in HW (transaction in progress), we still have drv->tcs_in_use set. So the rpmh_rsc_invalidate() (invoked from rpmh_flush()) will keep on returning -EAGAIN until that TCS becomes free to use and then goes ahead to finish its job.

Ah, interesting. I still think you have problems I pointed out in another response because you never enable interrupts for the "WAKE TCS", but I can see how this could be made to work. In this case "async" becomes a little silly here because the flush will essentially be forced to wait until the transaction is totally done (so the TCS is free again), but it should be able to work.

This might actually point
out something that needs to be changed in my "clean up" series since I guess "tcs_in_use" could sometimes be present in a wake TCS now.

Quoted 32 lines

Quoted 32 lines

Quoted 19 lines

drivers/soc/qcom/rpmh-rsc.c +2 -0

index e278fc1..b6391e1 100644
@@ -61,6 +61,8 @@
 #define CMD_STATUS_ISSUED              BIT(8)
 #define CMD_STATUS_COMPL               BIT(16)
 
+#define FLUSH_DIRTY                    1
+
 static u32 read_tcs_reg(struct rsc_drv *drv, int reg, int tcs_id, int cmd_id)
 {
        return readl_relaxed(drv->tcs_base + reg + RSC_DRV_TCS_OFFSET * tcs_id +

@@ -670,13 +672,15 @@ static int rpmh_rsc_probe(struct platform_device *pdev)
        INIT_LIST_HEAD(&drv->client.cache);
        INIT_LIST_HEAD(&drv->client.batch_cache);
 

drivers/soc/qcom/rpmh-rsc.c static int rpmh_rsc_probe(struct platform_device *pdev) · line 683

Quoted 10 lines

drivers/soc/qcom/rpmh-rsc.c +3 -1

+       drv->client.flush_dirty = device_get_match_data(&pdev->dev);
+
        dev_set_drvdata(&pdev->dev, drv);
 
        return devm_of_platform_populate(&pdev->dev);
 }
 
 static const struct of_device_id rpmh_drv_match[] = {
-       { .compatible = "qcom,rpmh-rsc", },
+       { .compatible = "qcom,rpmh-rsc", .data = (void *)FLUSH_DIRTY },

Ick. This is just confusing. IMO better to set 'drv->client.flush_dirty = true' directly in probe with a comment saying that it could be removed if we had OSI.

Quoted 5 lines

Done.
i will keep this bit earlier in probe with commet, so later if we detect rsc to be in hierarchy from [1], we can override this to be 0 within rpmh_probe_power_domain().

[1] https://patchwork.kernel.org/patch/11391229/

I don't really understand, but maybe it'll be obvious when I see the code.

Quoted 60 lines

Quoted 7 lines

...and while you're at it, why not fire off a separate patch (not in your series) adding the stub to 'include/linux/psci.h'. Then when we revisit this in a year it'll be there and it'll be super easy to set the value properly.

With above approch to set it in probe accordingly PSCI change won't be required.

it will be simple, cleaner and without any resistance from PSCI perspective.

Quoted 49 lines

Quoted 37 lines

drivers/soc/qcom/rpmh-rsc.c +0 -0

        { }
 };
 

drivers/soc/qcom/rpmh.c +5 -3

index 5bed8f4..9d40209 100644
@@ -297,12 +297,10 @@ static int flush_batch(struct rpmh_ctrlr *ctrlr)
 {
        struct batch_cache_req *req;
        const struct rpmh_request *rpm_msg;
-       unsigned long flags;
        int ret = 0;
        int i;
 
        /* Send Sleep/Wake requests to the controller, expect no response */
-       spin_lock_irqsave(&ctrlr->cache_lock, flags);
        list_for_each_entry(req, &ctrlr->batch_cache, list) {
                for (i = 0; i < req->count; i++) {
                        rpm_msg = req->rpm_msgs + i;

@@ -312,7 +310,6 @@ static int flush_batch(struct rpmh_ctrlr *ctrlr)
                                break;
                }
        }
-       spin_unlock_irqrestore(&ctrlr->cache_lock, flags);
 
        return ret;
 }

@@ -433,16 +430,63 @@ static int send_single(struct rpmh_ctrlr *ctrlr, enum rpmh_state state,
 }
 
 /**
+ * rpmh_start_transaction: Indicates start of rpmh transactions, this
+ * must be ended by invoking rpmh_end_transaction().
+ *
+ * @dev: the device making the request
+ */

drivers/soc/qcom/rpmh.c static int send_single(struct rpmh_ctrlr *ctrlr, enum rpmh_state state, · line 447

Quoted 10 lines

drivers/soc/qcom/rpmh.c +10 -0

+void rpmh_start_transaction(const struct device *dev)
+{
+       struct rpmh_ctrlr *ctrlr = get_rpmh_ctrlr(dev);
+       unsigned long flags;
+
+       if (!ctrlr->flush_dirty)
+               return;
+
+       spin_lock_irqsave(&ctrlr->cache_lock, flags);
+       ctrlr->active_clients++;

Wouldn't hurt to have something like:

Quoted 6 lines

Quoted 5 lines

/*
* Detect likely leak; we shouldn't have 1000
* people making in-flight changes at the same time. */
WARN_ON(ctrlr->active_clients > 1000)

Not necessary change.

Yes, but it will catch buggy clients much more quickly. What are the downsides?

Quoted 25 lines

Quoted 17 lines

Quoted 17 lines

drivers/soc/qcom/rpmh.c +15 -0

+       spin_unlock_irqrestore(&ctrlr->cache_lock, flags);
+}
+EXPORT_SYMBOL(rpmh_start_transaction);
+
+/**
+ * rpmh_end_transaction: Indicates end of rpmh transactions. All dirty data
+ * in cache can be flushed immediately when ctrlr->flush_dirty is set
+ *
+ * @dev: the device making the request
+ *
+ * Return: 0 on success, error number otherwise.
+ */
+int rpmh_end_transaction(const struct device *dev)
+{
+       struct rpmh_ctrlr *ctrlr = get_rpmh_ctrlr(dev);

Quoted 8 lines

drivers/soc/qcom/rpmh.c static int send_single(struct rpmh_ctrlr *ctrlr, enum rpmh_state state, · line 469

Quoted 7 lines

drivers/soc/qcom/rpmh.c +7 -0

+       unsigned long flags;
+       int ret = 0;
+
+       if (!ctrlr->flush_dirty)
+               return ret;
+
+       spin_lock_irqsave(&ctrlr->cache_lock, flags);

WARN_ON(!active_clients);

Quoted 6 lines

Why? when active_clients become zero, we want to finally call rpmh_flush(), i don't see a reason to warn and then flush.

Or do you want to make a check if client really called rpmh_start_transaction() first before calling rpmh_end_transaction() then when we do ctrlr->active_clients--;

it shouldn't go to negative value at the end. in that case let me know, i will make those changes.

Right, I want to warn on underflow. AKA:

WARN_ON(!ctrlr->active_clients);
ctrlr->active_clients--;

Generally it's handy to detect mismatches of start/end. It could be that someone accidentally starts twice and ends once. Starts zero times and ends once. Starts once and ends twice. All of these are interesting cases to warn about.

-Doug

Hi,

Quoted 86 lines · Doug Anderson

Hi,

Quoted 40 lines · Maulik Shah

Quoted 29 lines · Doug Anderson

Hi,

Quoted 9 lines · Maulik Shah

Add changes to invoke rpmh flush() from within cache_lock when the data in cache is dirty.

Introduce two new APIs for this. Clients can use rpmh_start_transaction() before any rpmh transaction once done invoke rpmh_end_transaction() which internally invokes rpmh_flush() if the caches has become dirty.

Add support to control this with flush_dirty flag.

Quoted 8 lines

Signed-off-by Maulik Shah <[email protected]>

Reviewed-by Srinivas Rao L <[email protected]>

---
 drivers/soc/qcom/rpmh-internal.h |  4 +++
 drivers/soc/qcom/rpmh-rsc.c      |  6 +++-
 drivers/soc/qcom/rpmh.c          | 64 ++++++++++++++++++++++++++++++++--------
 include/soc/qcom/rpmh.h          | 10 +++++++
 4 files changed, 71 insertions(+), 13 deletions(-)

As mentioned previously but not addressed [3], I believe your series breaks things if there are zero ACTIVE TCSs and you're using the immediate-flush solution. Specifically any attempt to set something's "active" state will clobber the sleep/wake. I believe this is hard to fix, especially if you want rpmh_write_async() to work properly and need to be robust to the last man going down while rpmh_write_async() is running but hasn't finished. My suggestion was to consider it to be an error at probe time for now.

Quoted 7 lines

Actually, though, I'd be super surprised if the "active == 0" case works anyway. Aside from subtle problems of not handling -EAGAIN (see another previous message that you didn't respond to [2]), I think you'll also get failures because you never enable interrupts in RSC_DRV_IRQ_ENABLE for anything other than the ACTIVE_TCS. Thus you'll never get interrupts saying when your transactions on the borrowed "wake" TCS finish.

No, it shouldn’t effect even with "non-OSI-mode + 0 ACTIVE TCS"

Quoted 8 lines

i just replied on v9, pasting same on v13 as well.

After taking your suggestion to do rpmh start/end transaction() in v13, rpmh_end_transaction() invokes rpmh_flush() only for the last client and by this time expecting all of rpmh_write() and rpmh_write_batch() will be already “finished” as client first waits for them to finish and then only invokes end.

So driver is good to handle rpmh_write() and rpmh_write_batch() calls.

Ah, right. In the previous version of the patch it was a problem because you flushed in cache_rpm_request() and then clobbered it right away in __rpmh_write() when you did rpmh_rsc_send_data(). With v13 that is not the case anymore. So this case should be OK.

Quoted 6 lines

Regarding rpmh_write_async() call, which is a fire-n-forget request from SW and client driver may immediately invoke rpmh_end_transaction() after this.

this case is also handled properly…
Lets again take an example for understanding this..

Quoted 7 lines

1. Client invokes rpmh_write_async() to send ACTIVE cmds for targets which has zero ACTIVE TCS

Rpmh driver Re-purposes one of SLEEP/WAKE TCS to use as ACTIVE, internally this also sets drv->tcs_in_use to true for respective SLEEP/WAKE TCS.

2. Client now without waiting for above to finish, goes ahead and invokes rpmh_end_transaction()
which calls rpmh_flush() (in case cache become dirty)

I guess we'd have to confirm that there's no way for the cache to _not_ become dirty but you do an "active" transaction. Let's imagine this case:

start transaction rpmh_write(RPMH_ACTIVE_ONLY_STATE, addr=0x10, data=0x99); rpmh_write(RPMH_SLEEP_STATE, addr=0x10, data=0x11); rpmh_write(RPMH_WAKE_ONLY_STATE, addr=0x10, data=0x99); end transaction

start transaction rpmh_write(RPMH_ACTIVE_ONLY_STATE, addr=0x10, data=0x99); rpmh_write(RPMH_SLEEP_STATE, addr=0x10, data=0x11); rpmh_write(RPMH_WAKE_ONLY_STATE, addr=0x10, data=0x99); end transaction

Quoted 8 lines

In other words the client does the same sequence twice in a row with no change in data. After the first set I think you'd be fine. ...but after the second set you'll be in trouble. That's because none of the calls in the second set would cause the "dirty" to be set. ...but for "active only" calls we don't have any sort of cache--we just fire it off. When we fire off the active only we'll clobber the sleep/wake TCS. ...and then nothing will write them again because the cache isn't dirty.

Agree with above scenario, but i don't see a reason why would a rpmh client send the same request twice.

Let me explain...

while first request is a proper one (already handled in rpmh driver), second is again duplicate of first without any change.

when this duplicate request is triggered, resource may be in its own low power mode, when this extra/duplicate command is sent, it needs to come out of low power mode and apply the newly requested level but it is already at that level, so it will immediatly ack back without doing any real level transition, and it will again go back to sleep. so there can be a small power hit.

and also for "ACTIVE" we need to handle this unnecessary ack interrupt at CPU, so CPU (if it is in some low power mode where this interrupt is affined to) need to wake up and handle this interrupt, again taking possible power hit from CPU point.

whats more?

while this whole unnecessary ping-pong happens in HW and SW, client may be waiting if its a blocking call.

rpmh client is expected to "aggregate" and finally do rpmh transaction "only if" aggregated final level differs from what resource is already having.

if they are not doing this, then IMO, this is something to be addressed from client side.

Quoted 9 lines

Quoted 3 lines

Now if re-purposed TCS is still in use in HW (transaction in progress), we still have drv->tcs_in_use set. So the rpmh_rsc_invalidate() (invoked from rpmh_flush()) will keep on returning -EAGAIN until that TCS becomes free to use and then goes ahead to finish its job.

Ah, interesting. I still think you have problems I pointed out in another response because you never enable interrupts for the "WAKE TCS", but I can see how this could be made to work. In this case "async" becomes a little silly here because the flush will essentially be forced to wait until the transaction is totally done (so the TCS is free again), but it should be able to work.

Agree, but i guess, this is a hit expected with non-OSI to do rpm_flush() immediately.

Quoted 3 lines

This might actually point
out something that needs to be changed in my "clean up" series since I guess "tcs_in_use" could sometimes be present in a wake TCS now.

yes this still need to keep.

Quoted 30 lines

Quoted 30 lines

Quoted 30 lines

Quoted 17 lines

drivers/soc/qcom/rpmh-rsc.c +2 -0

index e278fc1..b6391e1 100644
@@ -61,6 +61,8 @@
 #define CMD_STATUS_ISSUED              BIT(8)
 #define CMD_STATUS_COMPL               BIT(16)
 
+#define FLUSH_DIRTY                    1
+
 static u32 read_tcs_reg(struct rsc_drv *drv, int reg, int tcs_id, int cmd_id)
 {
        return readl_relaxed(drv->tcs_base + reg + RSC_DRV_TCS_OFFSET * tcs_id +

@@ -670,13 +672,15 @@ static int rpmh_rsc_probe(struct platform_device *pdev)
        INIT_LIST_HEAD(&drv->client.cache);
        INIT_LIST_HEAD(&drv->client.batch_cache);
 

drivers/soc/qcom/rpmh-rsc.c static int rpmh_rsc_probe(struct platform_device *pdev) · line 683

Quoted 10 lines

drivers/soc/qcom/rpmh-rsc.c +3 -1

+       drv->client.flush_dirty = device_get_match_data(&pdev->dev);
+
        dev_set_drvdata(&pdev->dev, drv);
 
        return devm_of_platform_populate(&pdev->dev);
 }
 
 static const struct of_device_id rpmh_drv_match[] = {
-       { .compatible = "qcom,rpmh-rsc", },
+       { .compatible = "qcom,rpmh-rsc", .data = (void *)FLUSH_DIRTY },

Ick. This is just confusing. IMO better to set 'drv->client.flush_dirty = true' directly in probe with a comment saying that it could be removed if we had OSI.

Quoted 6 lines

Quoted 5 lines

Done.
i will keep this bit earlier in probe with commet, so later if we detect rsc to be in hierarchy from [1], we can override this to be 0 within rpmh_probe_power_domain().

[1] https://patchwork.kernel.org/patch/11391229/

I don't really understand, but maybe it'll be obvious when I see the code.

okay.

Quoted 65 lines

Quoted 65 lines

Quoted 7 lines

...and while you're at it, why not fire off a separate patch (not in your series) adding the stub to 'include/linux/psci.h'. Then when we revisit this in a year it'll be there and it'll be super easy to set the value properly.

With above approch to set it in probe accordingly PSCI change won't be required.

it will be simple, cleaner and without any resistance from PSCI perspective.

Quoted 54 lines

Quoted 37 lines

drivers/soc/qcom/rpmh-rsc.c +0 -0

        { }
 };
 

drivers/soc/qcom/rpmh.c +5 -3

index 5bed8f4..9d40209 100644
@@ -297,12 +297,10 @@ static int flush_batch(struct rpmh_ctrlr *ctrlr)
 {
        struct batch_cache_req *req;
        const struct rpmh_request *rpm_msg;
-       unsigned long flags;
        int ret = 0;
        int i;
 
        /* Send Sleep/Wake requests to the controller, expect no response */
-       spin_lock_irqsave(&ctrlr->cache_lock, flags);
        list_for_each_entry(req, &ctrlr->batch_cache, list) {
                for (i = 0; i < req->count; i++) {
                        rpm_msg = req->rpm_msgs + i;

@@ -312,7 +310,6 @@ static int flush_batch(struct rpmh_ctrlr *ctrlr)
                                break;
                }
        }
-       spin_unlock_irqrestore(&ctrlr->cache_lock, flags);
 
        return ret;
 }

@@ -433,16 +430,63 @@ static int send_single(struct rpmh_ctrlr *ctrlr, enum rpmh_state state,
 }
 
 /**
+ * rpmh_start_transaction: Indicates start of rpmh transactions, this
+ * must be ended by invoking rpmh_end_transaction().
+ *
+ * @dev: the device making the request
+ */

drivers/soc/qcom/rpmh.c static int send_single(struct rpmh_ctrlr *ctrlr, enum rpmh_state state, · line 447

Quoted 10 lines

drivers/soc/qcom/rpmh.c +10 -0

+void rpmh_start_transaction(const struct device *dev)
+{
+       struct rpmh_ctrlr *ctrlr = get_rpmh_ctrlr(dev);
+       unsigned long flags;
+
+       if (!ctrlr->flush_dirty)
+               return;
+
+       spin_lock_irqsave(&ctrlr->cache_lock, flags);
+       ctrlr->active_clients++;

Wouldn't hurt to have something like:

/*
* Detect likely leak; we shouldn't have 1000
* people making in-flight changes at the same time. */
WARN_ON(ctrlr->active_clients > 1000)

Quoted 2 lines

Quoted 1 line

Not necessary change.

Yes, but it will catch buggy clients much more quickly. What are the downsides?

IMO, its uncessary warning that too with arbitrary number (1000).
rpmh clients are not expected to bombard it with thousands of requests, as i explained above, they need to aggregate and make rpmh request only when real level transistion needed.

Quoted 5 lines

Specifically I wouldn't trust all callers of rpmh_write() / rpmh_write_async() to never send the same data. If it was just an speed/power optimization then sure you could trust them, but this is for correctness.

yes we should trust callers not to send duplicate data.

Quoted 8 lines

Hrmm, thinking about this again, though, I'm still not convinced I understand what prevents the firmware from triggering "sleep mode" while the sleep/wake TCS is being borrowed for an active-only transaction. If we're sitting in rpmh_write() and sleeping in wait_for_completion_timeout() couldn't the system go idle and trigger sleep mode? In OSI-mode (with last man down) you'll always have a rpmh_flush() called by the last man down so you know you can make sure you're in a consistent state (one final flush and no more active-only

transactions will happen). Without last man down you have to assume

Quoted 5 lines

it can happen at any time don't you?

...so I guess I'll go back to asserting that zero-active-TCS is incompatible with non-OSI unless you have some way to prevent the sleep mode from being triggered while you've borrowed the wake TCS.

i had change for this in v4 to handle same.

Link https://patchwork.kernel.org/patch/11366205/

+ /*
+ * RPMh domain can not be powered off when there is pending ACK for
+ * ACTIVE_TCS request. Exit when controller is busy.
+ */

before calling rpmh_flush() we check ctrlr is idle (ensuring

tcs_is_free() check passes) this will ensure that

previous active transaction is completed before going ahead.

i will add this check in v14.

since this curretntly check for ACTIVE TCS only, i will update it to check the repurposed "WAKE TCS" is also free.

Quoted 7 lines

This whole "no active TCS" is really quite a mess. Given how broken it seems to me it almost feels like we should remove "no active TCS" from the driver for now and then re-add it in a later patch when we can really validate everything. I tried addressing this in my rpmh-rsc cleanup series and every time I thought I had a good solution I could find another way to break it.

Quoted 6 lines

Do you actually have the "no active TCS" case working on the current code, or does it only work on some downstream variant of the driver?

It works fine on downstream variant. Some checks are still needed like above from v4

since we do rpmh_flush() immediatly for dirty caches now.

Quoted 23 lines

I'm not saying we should limit the total number of requests to 1000. I'm saying that if there are 1000 active clients then that's a problem. Right now there are something like 4 clients. It doesn't matter how fast those clients are sending, active_clients will only be at most 4 and that would only be if they were all running their code at the exact same time.

I want to be able to quickly detect this type of bug:

start_transaction()
ret = rpmh_write()
if (ret)
return ret;
ret = rpmh_write()
end_transaction()
return ret;

...in other words: someone has a code path where start_transaction() is called but never end_transaction(). I'm proposing that if we ever see the ridiculous value of 1000 active clients the only way it could happen is if one of the clients started more times than they ended.

Quoted 4 lines

I guess maybe by the time there were 1000 it would be too late, though, because we'd have skipped A LOT of flushes by then? Maybe instead we should add something where if RPMH is "ditry" for more than a certain amount of time we put a warning?

IMO, we should not add any such warning with any number.
There are only 4 clients and unlikely to have any new ones. those 4 we should be able to ensure that they invoke end_transaction(), if they have already done start_transaction().beside, Function description also says that "this must be ended by invoking rpmh_end_transaction()" i am ok to also add saying that "rpmh do not check this, so its caller's responsibility to end it"

Hi,

Quoting below may look funny since you replied with HTML mail and all old quoting was lost. :( I tried my best.

Quoted 5 lines · Maulik Shah

Quoted 4 lines

Specifically I wouldn't trust all callers of rpmh_write() / rpmh_write_async() to never send the same data. If it was just an speed/power optimization then sure you could trust them, but this is for correctness.

yes we should trust callers not to send duplicate data.

I guess we'll see how this works out. Since this only affects the "zero active-only" case and I'm pretty sure that case has more important issues, I'm OK w/ ignoring for now.

Quoted 25 lines

Quoted 8 lines

Hrmm, thinking about this again, though, I'm still not convinced I understand what prevents the firmware from triggering "sleep mode" while the sleep/wake TCS is being borrowed for an active-only transaction. If we're sitting in rpmh_write() and sleeping in wait_for_completion_timeout() couldn't the system go idle and trigger sleep mode? In OSI-mode (with last man down) you'll always have a rpmh_flush() called by the last man down so you know you can make sure you're in a consistent state (one final flush and no more active-only

transactions will happen). Without last man down you have to assume

Quoted 5 lines

it can happen at any time don't you?

...so I guess I'll go back to asserting that zero-active-TCS is incompatible with non-OSI unless you have some way to prevent the sleep mode from being triggered while you've borrowed the wake TCS.

i had change for this in v4 to handle same.

Link https://patchwork.kernel.org/patch/11366205/

+ /*
+ * RPMh domain can not be powered off when there is pending ACK for
+ * ACTIVE_TCS request. Exit when controller is busy.
+ */

before calling rpmh_flush() we check ctrlr is idle (ensuring

Quoted 7 lines

tcs_is_free() check passes) this will ensure that

previous active transaction is completed before going ahead.

i will add this check in v14.

since this curretntly check for ACTIVE TCS only, i will update it to check the repurposed "WAKE TCS" is also free.

The difficulty isn't in adding a simple check, it's in adding a check that is race free and handles locking properly. Specifically looking at your the v4 you pointed to, I see things like this:

  if (!rpmh_rsc_ctrlr_is_idle(drv))
    return -EBUSY;
  return rpmh_flush(&drv->client);

The rpmh_rsc_ctrlr_is_idle() grabs a spin lock implying that there could be other people acting on RPMh at the same time (otherwise, why do you even need locks?). ...but when it returns the lock is released. Once the lock is dropped then other clients are free to start using RPMH because nothing prevents them. ...then you go ahead and start flushing.

Said another way: due to the way you've structured locking in that patch rpmh_rsc_ctrlr_is_idle() is inherently dangerous because it returns an instantaneous state that may well have changed between the spin_unlock_irqrestore() at the end of the function and when the function returns.

You could, of course, fix this by requiring that the caller hold the 'drv->lock' for both the calls to rpmh_rsc_ctrlr_is_idle() and rpmh_flush() (ignoring the fact the drv->lock is nominally part of rpmh-rsc.c and not rpmh.c). Now it would be safe from the problem I described. ...but now you get into a new problem. If you ever hold two locks you always need to make sure you grab them in the same order any time you grab them both. ...but tcs_write() we first grab a tcs_lock and _then_ drv->lock. That means the "fix" of holding drv->lock for both the calls to rpmh_rsc_ctrlr_is_idle() and rpmh_flush() won't work because rpmh_flush() will need to grab a tcs_lock. Possibly we could make this work by eliminating the "tcs lock" and just having the one big "drv->lock" protect everything (or introducing a new "super lock" making the other two meaningless). It would certainly be easier to reason about...

NOTE: the only way I'm able to reason about all the above things is because I spent all the time to document what rpmh-rsc is doing and what assumptions the various functions had [1]. It'd be great if that could get a review.

Quoted 12 lines

Quoted 12 lines

This whole "no active TCS" is really quite a mess. Given how broken it seems to me it almost feels like we should remove "no active TCS" from the driver for now and then re-add it in a later patch when we can really validate everything. I tried addressing this in my rpmh-rsc cleanup series and every time I thought I had a good solution I could find another way to break it.

Do you actually have the "no active TCS" case working on the current code, or does it only work on some downstream variant of the driver?

Quoted 3 lines

Quoted 3 lines

It works fine on downstream variant. Some checks are still needed like above from v4

since we do rpmh_flush() immediatly for dirty caches now.

OK. So I take it you haven't tested the "zero active" case with the upstream code? In theory it should be easy to test, right? Just hack the driver to pretend there are zero active TCSs?

Which SoCs in specific need the zero active TCSs? We are spending a lot of time talking about this and reviewing the code with this in mind. It adds a lot of complexity to the driver. If nothing under active development needs it I think we should do ourselves a favor and remove it for now, then add it back later. Otherwise this whole process is just going to take a lot more time.

Quoted 27 lines

Quoted 23 lines

I'm not saying we should limit the total number of requests to 1000. I'm saying that if there are 1000 active clients then that's a problem. Right now there are something like 4 clients. It doesn't matter how fast those clients are sending, active_clients will only be at most 4 and that would only be if they were all running their code at the exact same time.

I want to be able to quickly detect this type of bug:

start_transaction()
ret = rpmh_write()
if (ret)
return ret;
ret = rpmh_write()
end_transaction()
return ret;

...in other words: someone has a code path where start_transaction() is called but never end_transaction(). I'm proposing that if we ever see the ridiculous value of 1000 active clients the only way it could happen is if one of the clients started more times than they ended.

Quoted 4 lines

I guess maybe by the time there were 1000 it would be too late, though, because we'd have skipped A LOT of flushes by then? Maybe instead we should add something where if RPMH is "ditry" for more than a certain amount of time we put a warning?

Quoted 6 lines

IMO, we should not add any such warning with any number.
There are only 4 clients and unlikely to have any new ones. those 4 we should be able to ensure that they invoke end_transaction(), if they have already done start_transaction().beside, Function description also says that "this must be ended by invoking rpmh_end_transaction()" i am ok to also add saying that "rpmh do not check this, so its caller's responsibility to end it"

I don't agree but I won't argue further. If you want to leave out the WARN() then so be it.

-Doug

[1] https://lore.kernel.org/r/20200311161104.RFT.v2.5.I52653eb85d7dc8981ee0dafcd0b6cc0f273e9425@changeid

Hi,

Quoted 69 lines · Doug Anderson

Hi,

Quoting below may look funny since you replied with HTML mail and all old quoting was lost. :( I tried my best.

Quoted 5 lines · Maulik Shah

Quoted 4 lines

Specifically I wouldn't trust all callers of rpmh_write() / rpmh_write_async() to never send the same data. If it was just an speed/power optimization then sure you could trust them, but this is for correctness.

yes we should trust callers not to send duplicate data.

I guess we'll see how this works out. Since this only affects the "zero active-only" case and I'm pretty sure that case has more important issues, I'm OK w/ ignoring for now.

Quoted 25 lines

Quoted 8 lines

Hrmm, thinking about this again, though, I'm still not convinced I understand what prevents the firmware from triggering "sleep mode" while the sleep/wake TCS is being borrowed for an active-only transaction. If we're sitting in rpmh_write() and sleeping in wait_for_completion_timeout() couldn't the system go idle and trigger sleep mode? In OSI-mode (with last man down) you'll always have a rpmh_flush() called by the last man down so you know you can make sure you're in a consistent state (one final flush and no more active-only

transactions will happen). Without last man down you have to assume

Quoted 5 lines

it can happen at any time don't you?

...so I guess I'll go back to asserting that zero-active-TCS is incompatible with non-OSI unless you have some way to prevent the sleep mode from being triggered while you've borrowed the wake TCS.

i had change for this in v4 to handle same.

Link https://patchwork.kernel.org/patch/11366205/

+ /*
+ * RPMh domain can not be powered off when there is pending ACK for
+ * ACTIVE_TCS request. Exit when controller is busy.
+ */

before calling rpmh_flush() we check ctrlr is idle (ensuring

Quoted 7 lines

tcs_is_free() check passes) this will ensure that

previous active transaction is completed before going ahead.

i will add this check in v14.

since this curretntly check for ACTIVE TCS only, i will update it to check the repurposed "WAKE TCS" is also free.

The difficulty isn't in adding a simple check, it's in adding a check that is race free and handles locking properly. Specifically looking at your the v4 you pointed to, I see things like this:

  if (!rpmh_rsc_ctrlr_is_idle(drv))
    return -EBUSY;
  return rpmh_flush(&drv->client);

The rpmh_rsc_ctrlr_is_idle() grabs a spin lock implying that there could be other people acting on RPMh at the same time (otherwise, why do you even need locks?). ...but when it returns the lock is released. Once the lock is dropped then other clients are free to start using RPMH because nothing prevents them. ...then you go ahead and start flushing.

Said another way: due to the way you've structured locking in that patch rpmh_rsc_ctrlr_is_idle() is inherently dangerous because it returns an instantaneous state that may well have changed between the spin_unlock_irqrestore() at the end of the function and when the function returns.

Quoted 14 lines

You could, of course, fix this by requiring that the caller hold the 'drv->lock' for both the calls to rpmh_rsc_ctrlr_is_idle() and rpmh_flush() (ignoring the fact the drv->lock is nominally part of rpmh-rsc.c and not rpmh.c). Now it would be safe from the problem I described. ...but now you get into a new problem. If you ever hold two locks you always need to make sure you grab them in the same order any time you grab them both. ...but tcs_write() we first grab a tcs_lock and _then_ drv->lock. That means the "fix" of holding drv->lock for both the calls to rpmh_rsc_ctrlr_is_idle() and rpmh_flush() won't work because rpmh_flush() will need to grab a tcs_lock. Possibly we could make this work by eliminating the "tcs lock" and just having the one big "drv->lock" protect everything (or introducing a new "super lock" making the other two meaningless). It would certainly be easier to reason about...

Thanks Doug.

Agree, a simple check won't help here.

From above discussions, summarizing out 3 items that gets impacted when using rpmh_start/end_transaction().

1. rpmh_write_async() becomes of little use since drivers may need to wait for rpmh_flush() to finish if caches becomes dirty in between.

2. It creates more pressure on WAKE TCS when there is no dedicated ACTIVE TCS. Transactions are delayed if rpmh_flush() is in progress holding the locks and new request comes in to send Active only data.
3. rpmh_rsc_ctrlr_is_idle() needs locking if ANY cpu can be calling this, this may require reordering of locks / increase the time for which locks are held during rpmh transactions. On downstream variant we don't have locking in this since in OSI, only last CPU is invoking it and it is the only one invoking this function.

Given above impact this approach seem not so simple as i though of earlier. i have alternate solution which uses cpu_pm_notifications() and invokes rpmh_flush() for non-OSI targets. This approach should not impact above 3 items.

I will soon post out v14 with this, testing in progress.

Quoted 5 lines

NOTE: the only way I'm able to reason about all the above things is because I spent all the time to document what rpmh-rsc is doing and what assumptions the various functions had [1]. It'd be great if that could get a review.

Sure.

Quoted 12 lines

Quoted 12 lines

Quoted 12 lines

This whole "no active TCS" is really quite a mess. Given how broken it seems to me it almost feels like we should remove "no active TCS" from the driver for now and then re-add it in a later patch when we can really validate everything. I tried addressing this in my rpmh-rsc cleanup series and every time I thought I had a good solution I could find another way to break it.

Do you actually have the "no active TCS" case working on the current code, or does it only work on some downstream variant of the driver?

Quoted 6 lines

Quoted 3 lines

Quoted 3 lines

It works fine on downstream variant. Some checks are still needed like above from v4

since we do rpmh_flush() immediatly for dirty caches now.

OK. So I take it you haven't tested the "zero active" case with the upstream code? In theory it should be easy to test, right? Just hack the driver to pretend there are zero active TCSs?

No, it won't work out this way. if we want to test with zero active case, need to pick up [2].

[2] also need follow up fixes to work. This change is also in my to do
list to get merged. I will include a change in v14 series at the end, it can help test this series for zero active tcs as well.

Note that it doesn't have any dependency with this series and current series can get merged without [2].

Quoted 7 lines

Which SoCs in specific need the zero active TCSs? We are spending a lot of time talking about this and reviewing the code with this in mind. It adds a lot of complexity to the driver. If nothing under active development needs it I think we should do ourselves a favor and remove it for now, then add it back later. Otherwise this whole process is just going to take a lot more time.

There are multiple SoCs having zero active TCSes in downstream code. So we can not remove it.

As i said above we need [2] plus some fixes to have zero active TCS working fine on upstream driver.

Update all rpmh clients to start using rpmh_start_transaction() and rpmh_end_transaction().

Cc Taniya Das <[email protected]>

Cc Odelu Kukatla <[email protected]>

Cc Kiran Gunda <[email protected]>

Cc Sibi Sankar <[email protected]>

Signed-off-by Maulik Shah <[email protected]>

---
 drivers/clk/qcom/clk-rpmh.c             | 21 ++++++++++++++-------
 drivers/interconnect/qcom/bcm-voter.c   | 13 +++++++++----
 drivers/regulator/qcom-rpmh-regulator.c |  4 ++++
 drivers/soc/qcom/rpmhpd.c               | 11 +++++++++--

 4 files changed, 36 insertions(+), 13 deletions(-)

drivers/clk/qcom/clk-rpmh.c +2 -3

index 12bd871..16f68d4 100644
@@ -154,22 +154,27 @@ static int clk_rpmh_send_aggregate_command(struct clk_rpmh *c)
        cmd_state = c->aggr_state;
        on_val = c->res_on_val;
 
+       rpmh_start_transaction(c->dev);
+
        for (; state <= RPMH_ACTIVE_ONLY_STATE; state++) {
                if (has_state_changed(c, state)) {
                        if (cmd_state & BIT(state))
                                cmd.data = on_val;
 
                        ret = rpmh_write_async(c->dev, state, &cmd, 1);
-                       if (ret) {
-                               dev_err(c->dev, "set %s state of %s failed: (%d)\n",
-                                       !state ? "sleep" :

drivers/clk/qcom/clk-rpmh.c +0 -0

        if (ret) {
                dev_err(c->dev, "set active state of %s failed: (%d)\n",
                        c->res_name, ret);

drivers/interconnect/qcom/bcm-voter.c +4 -2

index 2adfde8..fbe18b2 100644
@@ -263,7 +263,9 @@ int qcom_icc_bcm_voter_commit(struct bcm_voter *voter)
        tcs_list_gen(&voter->commit_list, QCOM_ICC_BUCKET_AMC, cmds, commit_idx);
 
        if (!commit_idx[0])
-               goto out;
+               goto end;
+
+       rpmh_start_transaction(voter-dev);
 
        ret = rpmh_invalidate(voter->dev);
        if (ret) {

@@ -312,12 +314,15 @@ int qcom_icc_bcm_voter_commit(struct bcm_voter *voter)
        tcs_list_gen(&voter->commit_list, QCOM_ICC_BUCKET_SLEEP, cmds, commit_idx);
 
        ret = rpmh_write_batch(voter->dev, RPMH_SLEEP_STATE, cmds, commit_idx);
-       if (ret) {
+       if (ret)

drivers/interconnect/qcom/bcm-voter.c +0 -0

        list_for_each_entry_safe(bcm, bcm_tmp, &voter->commit_list, list)
                list_del_init(&bcm->list);
 

drivers/regulator/qcom-rpmh-regulator.c +0 -0

index c86ad40..f4b9176 100644
@@ -163,12 +163,16 @@ static int rpmh_regulator_send_request(struct rpmh_vreg *vreg,
 {
        int ret;

drivers/regulator/qcom-rpmh-regulator.c +1 -0

+
        return ret;
 }
 

drivers/soc/qcom/rpmhpd.c +3 -0

index 4d264d0..0e9d204 100644
@@ -193,19 +193,26 @@ static const struct of_device_id rpmhpd_match_table[] = {
 static int rpmhpd_send_corner(struct rpmhpd *pd, int state,
                              unsigned int corner, bool sync)
 {
+       int ret;
        struct tcs_cmd cmd = {
                .addr = pd->addr,
                .data = corner,
        };
 
+       rpmh_start_transaction(pd->dev);
+
        /*
         * Wait for an ack only when we are increasing the

Hi,

Quoted 8 lines · Maulik Shah

Update all rpmh clients to start using rpmh_start_transaction() and rpmh_end_transaction().

Cc Taniya Das <[email protected]>

Cc Odelu Kukatla <[email protected]>

Cc Kiran Gunda <[email protected]>

Cc Sibi Sankar <[email protected]>

Signed-off-by Maulik Shah <[email protected]>

Quoted 5 lines

---
 drivers/clk/qcom/clk-rpmh.c             | 21 ++++++++++++++-------
 drivers/interconnect/qcom/bcm-voter.c   | 13 +++++++++----
 drivers/regulator/qcom-rpmh-regulator.c |  4 ++++
 drivers/soc/qcom/rpmhpd.c               | 11 +++++++++--

This needs to be 4 separate patches since the change to each subsystem will go through a different maintainer.

Also: it'll be a lot easier to land this if you make the new rpmh_start_transaction() and rpmh_end_transaction() calls _optional_ for now, especially since they are just a speed optimization and not for correctness. That is, if a driver makes a call to rpmh_write(), rpmh_write_async(), rpmh_write_batch(), or rpmh_invalidate() without doing rpmh_start_transaction() then it should still work

--just flush
right away.

Since you have rpmh_start_transaction() refcounted that's as simple as making a call to rpmh_start_transaction() at the beginning of all public calls and rpmh_end_transaction() at the end. If there was already a refcount then no harm done. If there wasn't you'll get a flush at the end.

Once you make the call optional, you can actually leave changing the callers until after your series lands. Then you don't end up bothering all the other maintainers with the back-and-forth.

Once all callers are updated you can make the call required. ...or (as noted below) maybe we should just keep it optional...

One last note here: you have a regulator change here but aren't sending it to the regulator maintainer. That won't work. You also have an interconnect change without sending it to the interconnect maintainer.

Quoted 23 lines

 4 files changed, 36 insertions(+), 13 deletions(-)

drivers/clk/qcom/clk-rpmh.c +2 -3

index 12bd871..16f68d4 100644
@@ -154,22 +154,27 @@ static int clk_rpmh_send_aggregate_command(struct clk_rpmh *c)
        cmd_state = c->aggr_state;
        on_val = c->res_on_val;
 
+       rpmh_start_transaction(c->dev);
+
        for (; state <= RPMH_ACTIVE_ONLY_STATE; state++) {
                if (has_state_changed(c, state)) {
                        if (cmd_state & BIT(state))
                                cmd.data = on_val;
 
                        ret = rpmh_write_async(c->dev, state, &cmd, 1);
-                       if (ret) {
-                               dev_err(c->dev, "set %s state of %s failed: (%d)\n",
-                                       !state ? "sleep" :

drivers/clk/qcom/clk-rpmh.c static int clk_rpmh_send_aggregate_command(struct clk_rpmh *c) · line 170

Quoted 10 lines

drivers/clk/qcom/clk-rpmh.c +3 -4

-                                       state == RPMH_WAKE_ONLY_STATE   ?
-                                       "wake" : "active", c->res_name, ret);
-                               return ret;
-                       }
+                       if (ret)
+                               break;
                }
        }
 
+       ret |= rpmh_end_transaction(c->dev);

You can't do this. "ret" is an integer and you're munging two error codes into one int. I don't think there is any clever way to do this, but probably this would be fine (the compiler should optimize):

if (ret)
rpmh_end_transaction(c->dev);
else
ret = rpmh_end_transaction(c->dev);

...or just leave the "dev_err" and "return ret" where they were and call rpmh_end_transaction() above without looking at the return value.

drivers/clk/qcom/clk-rpmh.c static int clk_rpmh_send_aggregate_command(struct clk_rpmh *c) · line 176

Quoted 8 lines

drivers/clk/qcom/clk-rpmh.c +6 -0

+       if (ret) {
+               dev_err(c->dev, "set %s state of %s failed: (%d)\n",
+                       !state ? "sleep" : state == RPMH_WAKE_ONLY_STATE ?
+                       "wake" : "active", c->res_name, ret);
+               return ret;
+       }

Technically the error message above is now misleading if the "end_transaction" failed. Namely it will blame things on the active only state whereas that wasn't the problem.

Quoted 4 lines

drivers/clk/qcom/clk-rpmh.c +1 -0

+
        c->last_sent_aggr_state = c->aggr_state;
        c->peer->last_sent_aggr_state =  c->last_sent_aggr_state;
 

drivers/clk/qcom/clk-rpmh.c static int clk_rpmh_bcm_send_cmd(struct clk_rpmh *c, bool enable) · line 277

Quoted 7 lines

drivers/clk/qcom/clk-rpmh.c +2 -0

@@ -267,7 +272,9 @@ static int clk_rpmh_bcm_send_cmd(struct clk_rpmh *c, bool enable)
        cmd.addr = c->res_addr;
        cmd.data = BCM_TCS_CMD(1, enable, 0, cmd_state);
 
+       rpmh_start_transaction(c->dev);
        ret = rpmh_write_async(c->dev, RPMH_ACTIVE_ONLY_STATE, &cmd, 1);
+       ret |= rpmh_end_transaction(c->dev);

Again, no |=

Also: one argument for keeping start_transaction and end_transaction optional long term is that you could completely eliminate this change.

Quoted 25 lines

drivers/clk/qcom/clk-rpmh.c +0 -0

        if (ret) {
                dev_err(c->dev, "set active state of %s failed: (%d)\n",
                        c->res_name, ret);

drivers/interconnect/qcom/bcm-voter.c +4 -2

index 2adfde8..fbe18b2 100644
@@ -263,7 +263,9 @@ int qcom_icc_bcm_voter_commit(struct bcm_voter *voter)
        tcs_list_gen(&voter->commit_list, QCOM_ICC_BUCKET_AMC, cmds, commit_idx);
 
        if (!commit_idx[0])
-               goto out;
+               goto end;
+
+       rpmh_start_transaction(voter-dev);
 
        ret = rpmh_invalidate(voter->dev);
        if (ret) {

@@ -312,12 +314,15 @@ int qcom_icc_bcm_voter_commit(struct bcm_voter *voter)
        tcs_list_gen(&voter->commit_list, QCOM_ICC_BUCKET_SLEEP, cmds, commit_idx);
 
        ret = rpmh_write_batch(voter->dev, RPMH_SLEEP_STATE, cmds, commit_idx);
-       if (ret) {
+       if (ret)

drivers/interconnect/qcom/bcm-voter.c int qcom_icc_bcm_voter_commit(struct bcm_voter *voter) · line 325

Quoted 10 lines

drivers/interconnect/qcom/bcm-voter.c +5 -2

                pr_err("Error sending SLEEP RPMH requests (%d)\n", ret);
-               goto out;
-       }
 
 out:
+       ret = rpmh_end_transaction(voter-dev);
+       if (ret)
+               pr_err("Error ending rpmh transaction (%d)\n", ret);
+
+end:

Personally I don't think "out" and "end" are very descriptive. My own favorite is to name these types of labels based on what has been done so far. So:

exit_started_rpmh_transaction:
exit_constructed_list:

Quoted 19 lines

drivers/interconnect/qcom/bcm-voter.c +0 -0

        list_for_each_entry_safe(bcm, bcm_tmp, &voter->commit_list, list)
                list_del_init(&bcm->list);
 

drivers/regulator/qcom-rpmh-regulator.c +2 -0

index c86ad40..f4b9176 100644
@@ -163,12 +163,16 @@ static int rpmh_regulator_send_request(struct rpmh_vreg *vreg,
 {
        int ret;
 
+       rpmh_start_transaction(vreg->dev);
+
        if (wait_for_ack || vreg->always_wait_for_ack)
                ret = rpmh_write(vreg->dev, RPMH_ACTIVE_ONLY_STATE, cmd, 1);
        else
                ret = rpmh_write_async(vreg->dev, RPMH_ACTIVE_ONLY_STATE, cmd,
                                        1);
 

drivers/regulator/qcom-rpmh-regulator.c static int rpmh_regulator_send_request(struct rpmh_vreg *vreg, · line 174

Quoted 1 line

drivers/regulator/qcom-rpmh-regulator.c +1 -0

+       ret |= rpmh_end_transaction(vreg->dev);

Again, no |=.

...and again, if starting/ending was optional you wouldn't need this change.

Quoted 18 lines

drivers/regulator/qcom-rpmh-regulator.c +1 -0

+
        return ret;
 }
 

drivers/soc/qcom/rpmhpd.c +1 -0

index 4d264d0..0e9d204 100644
@@ -193,19 +193,26 @@ static const struct of_device_id rpmhpd_match_table[] = {
 static int rpmhpd_send_corner(struct rpmhpd *pd, int state,
                              unsigned int corner, bool sync)
 {
+       int ret;
        struct tcs_cmd cmd = {
                .addr = pd->addr,
                .data = corner,
        };
 

Quoted 4 lines

drivers/soc/qcom/rpmhpd.c +2 -0

+       rpmh_start_transaction(pd->dev);
+
        /*
         * Wait for an ack only when we are increasing the

drivers/soc/qcom/rpmhpd.c static const struct of_device_id rpmhpd_match_table[] = { · line 213

Quoted 10 lines

drivers/soc/qcom/rpmhpd.c +4 -2

         * perf state of the power domain
         */
        if (sync)
-               return rpmh_write(pd->dev, state, &cmd, 1);
+               ret = rpmh_write(pd->dev, state, &cmd, 1);
        else
-               return rpmh_write_async(pd->dev, state, &cmd, 1);
+               ret = rpmh_write_async(pd->dev, state, &cmd, 1);
+
+       ret |= rpmh_end_transaction(pd->dev);

Again, no |=.

...and again, if starting/ending was optional you wouldn't need this change.

-Doug

Quoted 16 lines · Doug Anderson

Hi,

Quoted 8 lines · Maulik Shah

Update all rpmh clients to start using rpmh_start_transaction() and rpmh_end_transaction().

Cc Taniya Das <[email protected]>

Cc Odelu Kukatla <[email protected]>

Cc Kiran Gunda <[email protected]>

Cc Sibi Sankar <[email protected]>

Signed-off-by Maulik Shah <[email protected]>

Quoted 5 lines

---
 drivers/clk/qcom/clk-rpmh.c             | 21 ++++++++++++++-------
 drivers/interconnect/qcom/bcm-voter.c   | 13 +++++++++----
 drivers/regulator/qcom-rpmh-regulator.c |  4 ++++
 drivers/soc/qcom/rpmhpd.c               | 11 +++++++++--

Quoted 2 lines

This needs to be 4 separate patches since the change to each subsystem will go through a different maintainer.

I will split to 4 changes, and send each one to its respective mailing lists and maintainer/reviewer.

Quoted 7 lines

Also: it'll be a lot easier to land this if you make the new rpmh_start_transaction() and rpmh_end_transaction() calls _optional_ for now, especially since they are just a speed optimization and not for correctness. That is, if a driver makes a call to rpmh_write(), rpmh_write_async(), rpmh_write_batch(), or rpmh_invalidate() without doing rpmh_start_transaction() then it should still work

yes, this is already taken care.

All the calls from driver will go through as it is and won't fail even without calling new APIs. So they are already optional.

The comment in rpmh_start_transaction() is already saying if client "choose" to invoke this then this must be ended by calling rpmh_end_transaction(). if client don't invoke rpmh_start_transaction() in the first place then everything is expected work as if no change.

Quoted 2 lines

--just flush
right away.

No, currently also in driver no one is calling rpmh_flush().

so nothing breaks with series and no point in adding changes to flush right away and then remove them in same series.

when the clients starts invoking new APIs, rpmh_flush() will start getting invoked for the first time in driver.

drivers/interconnect/qcom/bcm-voter.c +3 -1

@@ -263,7 +263,9 @@ int qcom_icc_bcm_voter_commit(struct bcm_voter *voter)
        tcs_list_gen(&voter->commit_list, QCOM_ICC_BUCKET_AMC, cmds, commit_idx);
 
        if (!commit_idx[0])
-               goto out;
+               goto end;
+
+       rpmh_start_transaction(voter-dev);
 
        ret = rpmh_invalidate(voter->dev);
        if (ret) {

@@ -312,12 +314,15 @@ int qcom_icc_bcm_voter_commit(struct bcm_voter *voter)
        tcs_list_gen(&voter->commit_list, QCOM_ICC_BUCKET_SLEEP, cmds, commit_idx);

Changes in v13:
- Address Stephen's comment to maintain COMPILE_TEST
- Address Doug's comments and add new APIs for start and end transaction

Changes in v12:
- Kconfig change to remove COMPILE_TEST was dropped in v11, reinclude it.

Changes in v11:
- Address Doug's comments on change 2 and 3
- Include change to invalidate TCSes before flush from [4]

Changes in v10:
- Address Evan's comments to update commit message on change 2
- Add Evan's Reviewed by on change 2
- Remove comment from rpmh_flush() related to last CPU invoking it
- Rebase all changes on top of next-20200302

Changes in v9:
- Keep rpmh_flush() to invoke from within cache_lock
- Remove comments related to only last cpu invoking rpmh_flush()

Changes in v8:
- Address Stephen's comments on changes 2 and 3
- Add Reviewed by from Stephen on change 1

Changes in v7:
- Address Srinivas's comments to update commit text
- Add Reviewed by from Srinivas

Changes in v6:
- Drop 1 & 2 changes from v5 as they already landed in maintainer tree
- Drop 3 & 4 changes from v5 as no user at present for power domain in rsc
- Rename subject to appropriate since power domain changes are dropped
- Rebase other changes on top of next-20200221

Changes in v5:
- Add Rob's Acked by on dt-bindings change
- Drop firmware psci change
- Update cpuidle stats in dtsi to follow PC mode
- Include change to update dirty flag when data is updated from [4]
- Add change to invoke rpmh_flush when caches are dirty

Changes in v4:
- Add change to allow hierarchical topology in PC mode
- Drop hierarchical domain idle states converter from v3
- Address Merge sc7180 dtsi change to add low power modes

Changes in v3:
- Address Rob's comment on dt property value
- Address Stephen's comments on rpmh-rsc driver change
- Include sc7180 cpuidle low power mode changes from [1]
- Include hierarchical domain idle states converter change from [2]

Changes in v2:
- Add Stephen's Reviewed-By to the first three patches
- Addressed Stephen's comments on fourth patch
- Include changes to connect rpmh domain to cpuidle and genpds

Resource State Coordinator (RSC) is responsible for powering off/lowering the requirements from CPU subsystem for the associated hardware like buses, clocks, and regulators when all CPUs and cluster is powered down.

RSC power domain uses last-man activities provided by genpd framework based on Ulf Hansoon's patch series[3], when the cluster of CPUs enter deepest idle states. As a part of domain poweroff, RSC can lower resource state requirements by flushing the cached sleep and wake state votes for various resources.

[1] https://patchwork.kernel.org/patch/11218965
[2] https://patchwork.kernel.org/patch/10941671
[3] https://patchwork.kernel.org/project/linux-arm-msm/list/?series=222355
[4] https://patchwork.kernel.org/project/linux-arm-msm/list/?series=236503

Maulik Shah (3):
arm64: dts: qcom: sc7180: Add cpuidle low power states
soc: qcom: rpmh: Update dirty flag only when data changes
soc: qcom: rpmh: Invoke rpmh_flush for dirty caches

 arch/arm64/boot/dts/qcom/sc7180.dtsi | 78 ++++++++++++++++++++++++++++++++++++
 drivers/soc/qcom/rpmh.c              | 27 ++++++++++---
 2 files changed, 100 insertions(+), 5 deletions(-)

Hi,

Quoted 73 lines · Maulik Shah

Changes in v13:
- Address Stephen's comment to maintain COMPILE_TEST
- Address Doug's comments and add new APIs for start and end transaction

Changes in v12:
- Kconfig change to remove COMPILE_TEST was dropped in v11, reinclude it.

Changes in v11:
- Address Doug's comments on change 2 and 3
- Include change to invalidate TCSes before flush from [4]

Changes in v10:
- Address Evan's comments to update commit message on change 2
- Add Evan's Reviewed by on change 2
- Remove comment from rpmh_flush() related to last CPU invoking it
- Rebase all changes on top of next-20200302

Changes in v9:
- Keep rpmh_flush() to invoke from within cache_lock
- Remove comments related to only last cpu invoking rpmh_flush()

Changes in v8:
- Address Stephen's comments on changes 2 and 3
- Add Reviewed by from Stephen on change 1

Changes in v7:
- Address Srinivas's comments to update commit text
- Add Reviewed by from Srinivas

Changes in v6:
- Drop 1 & 2 changes from v5 as they already landed in maintainer tree
- Drop 3 & 4 changes from v5 as no user at present for power domain in rsc
- Rename subject to appropriate since power domain changes are dropped
- Rebase other changes on top of next-20200221

Changes in v5:
- Add Rob's Acked by on dt-bindings change
- Drop firmware psci change
- Update cpuidle stats in dtsi to follow PC mode
- Include change to update dirty flag when data is updated from [4]
- Add change to invoke rpmh_flush when caches are dirty

Changes in v4:
- Add change to allow hierarchical topology in PC mode
- Drop hierarchical domain idle states converter from v3
- Address Merge sc7180 dtsi change to add low power modes

Changes in v3:
- Address Rob's comment on dt property value
- Address Stephen's comments on rpmh-rsc driver change
- Include sc7180 cpuidle low power mode changes from [1]
- Include hierarchical domain idle states converter change from [2]

Changes in v2:
- Add Stephen's Reviewed-By to the first three patches
- Addressed Stephen's comments on fourth patch
- Include changes to connect rpmh domain to cpuidle and genpds

Resource State Coordinator (RSC) is responsible for powering off/lowering the requirements from CPU subsystem for the associated hardware like buses, clocks, and regulators when all CPUs and cluster is powered down.

RSC power domain uses last-man activities provided by genpd framework based on Ulf Hansoon's patch series[3], when the cluster of CPUs enter deepest idle states. As a part of domain poweroff, RSC can lower resource state requirements by flushing the cached sleep and wake state votes for various resources.

[1] https://patchwork.kernel.org/patch/11218965
[2] https://patchwork.kernel.org/patch/10941671
[3] https://patchwork.kernel.org/project/linux-arm-msm/list/?series=222355
[4] https://patchwork.kernel.org/project/linux-arm-msm/list/?series=236503

Quoted 8 lines

Maulik Shah (3):
arm64: dts: qcom: sc7180: Add cpuidle low power states
soc: qcom: rpmh: Update dirty flag only when data changes
soc: qcom: rpmh: Invoke rpmh_flush for dirty caches

 arch/arm64/boot/dts/qcom/sc7180.dtsi | 78 ++++++++++++++++++++++++++++++++++++
 drivers/soc/qcom/rpmh.c              | 27 ++++++++++---
 2 files changed, 100 insertions(+), 5 deletions(-)

Did you happen to get a chance to test your patch against my cleanup / documentation patch? AKA:

https://lore.kernel.org/r/[email protected]

-Doug