OPP: Simplify set_required_opp handling

There is no real need of keeping separate code for single genpd case, it can be made to work with a simple change.

Signed-off-by Viresh Kumar <[email protected]>

---
 drivers/opp/core.c | 9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

drivers/opp/core.c +2 -8

index e87567dbe99f..6d7016ce8c53 100644
@@ -959,7 +959,8 @@ static int _set_required_opps(struct device *dev,
                              struct dev_pm_opp *opp, bool up)
 {
        struct opp_table **required_opp_tables = opp_table->required_opp_tables;
-       struct device **genpd_virt_devs = opp_table->genpd_virt_devs;
+       struct device **genpd_virt_devs =
+               opp_table->genpd_virt_devs ? opp_table->genpd_virt_devs : &dev;
        int i, ret = 0;
 
        if (!required_opp_tables)

@@ -979,12 +980,6 @@ static int _set_required_opps(struct device *dev,
                return -ENOENT;
        }
 
-       /* Single genpd case */
-       if (!genpd_virt_devs)
-               return _set_required_opp(dev, dev, opp, 0);
-
-       /* Multiple genpd case */
-
        /*
         * Acquire genpd_virt_dev_lock to make sure we don't use a genpd_dev
         * after it is freed from another thread.
--

2.31.1.272.g89b43f80a514

The required-opps configuration is closely tied to genpd and performance states at the moment and it is not very obvious that required-opps can live without genpds. Though we don't support configuring required-opps for non-genpd cases currently.

This commit aims at separating these parts, where configuring genpds would be a special case of configuring the required-opps.

Add a specialized callback, set_required_opps(), to the opp table and set it to different callbacks accordingly.

This shouldn't result in any functional changes for now.

Signed-off-by Viresh Kumar <[email protected]>

---
 drivers/opp/core.c | 69 ++++++++++++++++++++++++++++------------------
 drivers/opp/of.c   |  3 ++
 drivers/opp/opp.h  |  4 +++
 3 files changed, 49 insertions(+), 27 deletions(-)

drivers/opp/core.c +42 -27

index 6d7016ce8c53..954c94865cf5 100644
@@ -935,8 +935,8 @@ static int _set_opp_bw(const struct opp_table *opp_table,
        return 0;
 }
 
-static int _set_required_opp(struct device *dev, struct device *pd_dev,
-                            struct dev_pm_opp *opp, int i)
+static int _set_performance_state(struct device *dev, struct device *pd_dev,
+                                 struct dev_pm_opp *opp, int i)
 {
        unsigned int pstate = likely(opp) ? opp->required_opps[i]->pstate : 0;
        int ret;

@@ -953,33 +953,20 @@ static int _set_required_opp(struct device *dev, struct device *pd_dev,
        return ret;
 }
 
-/* This is only called for PM domain for now */
-static int _set_required_opps(struct device *dev,
-                             struct opp_table *opp_table,
-                             struct dev_pm_opp *opp, bool up)
+static int _opp_set_required_opps_generic(struct device *dev,
+       struct opp_table *opp_table, struct dev_pm_opp *opp, bool scaling_down)
+{
+       dev_err(dev, "setting required-opps isn't supported for non-genpd devices\n");
+       return -ENOENT;
+}
+
+static int _opp_set_required_opps_genpd(struct device *dev,
+       struct opp_table *opp_table, struct dev_pm_opp *opp, bool scaling_down)
 {
-       struct opp_table **required_opp_tables = opp_table->required_opp_tables;
        struct device **genpd_virt_devs =
                opp_table->genpd_virt_devs ? opp_table->genpd_virt_devs : &dev;
        int i, ret = 0;
 
-       if (!required_opp_tables)
-               return 0;
-
-       /* required-opps not fully initialized yet */
-       if (lazy_linking_pending(opp_table))
-               return -EBUSY;
-
-       /*
-        * We only support genpd's OPPs in the "required-opps" for now, as we
-        * don't know much about other use cases. Error out if the required OPP
-        * doesn't belong to a genpd.
-        */
-       if (unlikely(!required_opp_tables[0]->is_genpd)) {
-               dev_err(dev, "required-opps don't belong to a genpd\n");
-               return -ENOENT;
-       }
-
        /*
         * Acquire genpd_virt_dev_lock to make sure we don't use a genpd_dev
         * after it is freed from another thread.

@@ -987,15 +974,15 @@ static int _set_required_opps(struct device *dev,
        mutex_lock(&opp_table->genpd_virt_dev_lock);
 
        /* Scaling up? Set required OPPs in normal order, else reverse */
-       if (up) {
+       if (!scaling_down) {
                for (i = 0; i < opp_table->required_opp_count; i++) {
-                       ret = _set_required_opp(dev, genpd_virt_devs[i], opp, i);
+                       ret = _set_performance_state(dev, genpd_virt_devs[i], opp, i);
                        if (ret)
                                break;
                }
        } else {
                for (i = opp_table->required_opp_count - 1; i >= 0; i--) {
-                       ret = _set_required_opp(dev, genpd_virt_devs[i], opp, i);
+                       ret = _set_performance_state(dev, genpd_virt_devs[i], opp, i);
                        if (ret)
                                break;
                }

@@ -1006,6 +993,34 @@ static int _set_required_opps(struct device *dev,
        return ret;
 }
 
+/* This is only called for PM domain for now */
+static int _set_required_opps(struct device *dev, struct opp_table *opp_table,
+                             struct dev_pm_opp *opp, bool up)
+{
+       /* required-opps not fully initialized yet */
+       if (lazy_linking_pending(opp_table))
+               return -EBUSY;
+
+       if (opp_table->set_required_opps)
+               return opp_table->set_required_opps(dev, opp_table, opp, up);
+
+       return 0;
+}
+
+/* Update set_required_opps handler */
+void _update_set_required_opps(struct opp_table *opp_table)
+{
+       /* Already set */
+       if (opp_table->set_required_opps)
+               return;
+
+       /* All required OPPs will belong to genpd or none */
+       if (opp_table->required_opp_tables[0]->is_genpd)
+               opp_table->set_required_opps = _opp_set_required_opps_genpd;
+       else
+               opp_table->set_required_opps = _opp_set_required_opps_generic;
+}
+
 static void _find_current_opp(struct device *dev, struct opp_table *opp_table)
 {
        struct dev_pm_opp *opp = ERR_PTR(-ENODEV);

drivers/opp/of.c +3 -0

index e55c6095adf0..93da3c797afc 100644
@@ -196,6 +196,8 @@ static void _opp_table_alloc_required_tables(struct opp_table *opp_table,
        /* Let's do the linking later on */
        if (lazy)
                list_add(&opp_table->lazy, &lazy_opp_tables);
+       else
+               _update_set_required_opps(opp_table);
 
        goto put_np;
 

@@ -411,6 +413,7 @@ static void lazy_link_required_opp_table(struct opp_table *new_table)
 
                /* All required opp-tables found, remove from lazy list */
                if (!lazy) {
+                       _update_set_required_opps(opp_table);
                        list_del_init(&opp_table->lazy);
 
                        list_for_each_entry(opp, &opp_table->opp_list, node)

drivers/opp/opp.h +4 -1

index 3a6e077df386..2a057c42ddf4 100644
@@ -184,6 +184,7 @@ enum opp_table_access {
  * @enabled: Set to true if the device's resources are enabled/configured.
  * @genpd_performance_state: Device's power domain support performance state.
  * @is_genpd: Marks if the OPP table belongs to a genpd.
+ * @set_required_opps: Helper responsible to set required OPPs.
  * @dentry:    debugfs dentry pointer of the real device directory (not links).
  * @dentry_name: Name of the real dentry.
  *

@@ -234,6 +235,8 @@ struct opp_table {
        bool enabled;
        bool genpd_performance_state;
        bool is_genpd;
+       int (*set_required_opps)(struct device *dev,
+               struct opp_table *opp_table, struct dev_pm_opp *opp, bool scaling_down);
 
 #ifdef CONFIG_DEBUG_FS
        struct dentry *dentry;

@@ -257,6 +260,7 @@ void _dev_pm_opp_cpumask_remove_table(const struct cpumask *cpumask, int last_cp
 struct opp_table *_add_opp_table_indexed(struct device *dev, int index, bool getclk);
 void _put_opp_list_kref(struct opp_table *opp_table);
 void _required_opps_available(struct dev_pm_opp *opp, int count);
+void _update_set_required_opps(struct opp_table *opp_table);
 
 static inline bool lazy_linking_pending(struct opp_table *opp_table)
 {
--

2.31.1.272.g89b43f80a514

Quoted 12 lines · Viresh Kumar

The required-opps configuration is closely tied to genpd and performance states at the moment and it is not very obvious that required-opps can live without genpds. Though we don't support configuring required-opps for non-genpd cases currently.

This commit aims at separating these parts, where configuring genpds would be a special case of configuring the required-opps.

Add a specialized callback, set_required_opps(), to the opp table and set it to different callbacks accordingly.

Quoted 3 lines

This shouldn't result in any functional changes for now.

Signed-off-by Viresh Kumar <[email protected]>

This looks reasonable to me, but I guess it also depends on whether you will land patch3 or not?

Hello,

The required-opps configuration is closely tied to genpd and performance states at the moment and it is not very obvious that required-opps can live without genpds. Though we don't support configuring required-opps for non-genpd cases currently.

This patchset aims at cleaning up this a bit, just like what's done for clk and regulators. This also makes it possible for platforms to provide their own version of set_required_opps() helper, which can be used to configure the devfreq device propertly.

Jun,

I haven't found time to test this through yet, though there isn't much anyway I guess. Can you see if these can solve your problem properly ?

Viresh Kumar (3):
OPP: Handle all genpd cases together in _set_required_opps()
OPP: Move required opps configuration to specialized callback
OPP: Allow platforms to add a set_required_opps() callback

 drivers/opp/core.c     | 113 ++++++++++++++++++++++++++++-------------
 drivers/opp/of.c       |   3 ++
 drivers/opp/opp.h      |   4 ++
 include/linux/pm_opp.h |   5 ++
 4 files changed, 91 insertions(+), 34 deletions(-)

--
2.31.1.272.g89b43f80a514

It looks promising. The function get_target_freq_with_cpufreq() can be wrapped to act as set_required_opps() callback.

But my case is a bit complicated. CPU opp depends on both genpd opp and devfreq opp.

So the genpd_virt_devs array need
to be modified or add another array for devfreq case. While genpd_virt_devs is bounded with genpd directly and coupled with "power-domains" list in device tree.
Current required-opp nodes are designed to be aligned with the list. I am considering
what's the best way for back compatibility.

Quoted 5 lines · Jun Nie

It looks promising. The function get_target_freq_with_cpufreq() can be wrapped to act as set_required_opps() callback.

But my case is a bit complicated. CPU opp depends on both genpd opp and devfreq opp.

I was wondering if we will have such a case soon enough or not :)

Quoted 7 lines

So the genpd_virt_devs array need
to be modified or add another array for devfreq case. While genpd_virt_devs is bounded with genpd directly and coupled with "power-domains" list in device tree.
Current required-opp nodes are designed to be aligned with the list. I am considering
what's the best way for back compatibility.

Please look at the top commit here:

git://git.kernel.org/pub/scm/linux/kernel/git/vireshk/pm.git opp/propagate

Will this be enough for your use case ? I will post everything again once we are settled on a solution.

Signature · 2 lines

-- 
viresh

For the opp lib, this is right direction. We still need to find a method to pass devfreq device node to opp lib, just genpd_virt_devs for power domain.

But I am not clear below is the right way yet and this also involves wider changes. Or the opp's owner, devfreq device can be referred via opp lib? If so, we do not need to add devfreq-devs to cpu node at all.

		cpu1: cpu@101 {
			compatible = "arm,cortex-a53";
			device_type = "cpu";
			power-domains = <&cpr>;
			power-domain-names = "cpr";
			devfreq-devs = <&cci>;
			devfreq-names = "cci";

			operating-points-v2 = <&cluster1_opp_table>;
		};

		opp-200000000 {
			opp-hz = /bits/ 64 <200000000>;
			required-opps = <&cpr_opp3>, <&cci_opp1>;

		};

Quoted 2 lines · Jun Nie

For the opp lib, this is right direction. We still need to find a method to pass devfreq device node to opp lib, just genpd_virt_devs for power domain.

I am not really sure I understood it all. What is "device node" ? DT node or struct device ? What exactly do you need ?

Quoted 5 lines

But I am not clear below is the right way yet and this also involves wider changes. Or the opp's owner, devfreq device can be referred via opp lib? If so, we do not need to add devfreq-devs to cpu node at all.

Quoted 7 lines

              cpu1: cpu@101 {
                      compatible = "arm,cortex-a53";
                      device_type = "cpu";
                      power-domains = <&cpr>;
                      power-domain-names = "cpr";
                      devfreq-devs = <&cci>;
                      devfreq-names = "cci";

Why do you need these ?

Quoted 6 lines

                      operating-points-v2 = <&cluster1_opp_table>;
              };

              opp-200000000 {
                      opp-hz = /bits/ 64 <200000000>;
                      required-opps = <&cpr_opp3>, <&cci_opp1>;

This looks fine though.

Quoted 1 line

              };

--
viresh

Sorry for not expressing it accurately. I should say devfreq devices pointers, just
devfreq_virt_devs vs genpd_virt_devs. Then you know why I add devfreq-devs dts nodes below.

Quoted 4 lines · Jun Nie

Sorry for not expressing it accurately. I should say devfreq devices pointers, just
devfreq_virt_devs vs genpd_virt_devs. Then you know why I add devfreq-devs dts nodes below.

Won't something like dev_pm_opp_set_clkname() would be enough here too ? We already do this kind of work for clks and regulators.

Having power domain specific information within CPU nodes isn't a requirement of the OPP core, but the general requirement of genpd core instead.

--
viresh

Quoted 7 lines · Viresh Kumar <[email protected]> 于2023年2月27日周一 17:29写道：

Quoted 4 lines · Jun Nie

Sorry for not expressing it accurately. I should say devfreq devices pointers, just
devfreq_virt_devs vs genpd_virt_devs. Then you know why I add devfreq-devs dts nodes below.

Quoted 2 lines

Won't something like dev_pm_opp_set_clkname() would be enough here too ? We already do this kind of work for clks and regulators.

Thanks! It is a possible solution. I will try to spare time on this as higher priority tasks
are on my list.