Updates to MHI channel handling

Improve the channel handling state machine such that all commands go through a common function and validation process to ensure that the state machine is not violated in any way and adheres to the MHI specification. Assert device wake before sending the channel update commands instead of a wake toggle to ensure we fail if device is in a bad state. Also update print messages to use client device to accurately represent the channel being updated.

Signed-off-by Bhaumik Bhatt <[email protected]>

Reviewed-by Hemant Kumar <[email protected]>

---
 drivers/bus/mhi/core/init.c     |   6 ++
 drivers/bus/mhi/core/internal.h |  12 +++
 drivers/bus/mhi/core/main.c     | 172 ++++++++++++++++++++++------------------
 3 files changed, 114 insertions(+), 76 deletions(-)

drivers/bus/mhi/core/init.c +6 -0

index 03c5786..482b365 100644
@@ -54,6 +54,12 @@ const char * const mhi_state_str[MHI_STATE_MAX] = {
 	[MHI_STATE_SYS_ERR] = "SYS_ERR",
 };
 
+const char * const mhi_ch_state_type_str[MHI_CH_STATE_TYPE_MAX] = {
+	[MHI_CH_STATE_TYPE_RESET] = "RESET",
+	[MHI_CH_STATE_TYPE_STOP] = "STOP",
+	[MHI_CH_STATE_TYPE_START] = "START",
+};
+
 static const char * const mhi_pm_state_str[] = {
 	[MHI_PM_STATE_DISABLE] = "DISABLE",
 	[MHI_PM_STATE_POR] = "POR",

drivers/bus/mhi/core/internal.h +12 -0

index 6f80ec3..7e3aac1 100644
@@ -369,6 +369,18 @@ enum mhi_ch_state {
 	MHI_CH_STATE_ERROR = 0x5,
 };
 
+enum mhi_ch_state_type {
+	MHI_CH_STATE_TYPE_RESET,
+	MHI_CH_STATE_TYPE_STOP,
+	MHI_CH_STATE_TYPE_START,
+	MHI_CH_STATE_TYPE_MAX,
+};
+
+extern const char * const mhi_ch_state_type_str[MHI_CH_STATE_TYPE_MAX];
+#define TO_CH_STATE_TYPE_STR(state) (((state) >= MHI_CH_STATE_TYPE_MAX) ? \
+				     "INVALID_STATE" : \
+				     mhi_ch_state_type_str[(state)])
+
 #define MHI_INVALID_BRSTMODE(mode) (mode != MHI_DB_BRST_DISABLE && \
 				    mode != MHI_DB_BRST_ENABLE)
 

drivers/bus/mhi/core/main.c +96 -76

index d068188..2f6fdb2 100644
@@ -1188,56 +1188,114 @@ int mhi_send_cmd(struct mhi_controller *mhi_cntrl,
 	return 0;
 }
 
-static void __mhi_unprepare_channel(struct mhi_controller *mhi_cntrl,
-				    struct mhi_chan *mhi_chan)
+static int mhi_update_channel_state(struct mhi_controller *mhi_cntrl,
+				    struct mhi_chan *mhi_chan,
+				    enum mhi_ch_state_type to_state)
 {
-	int ret;
-	struct device *dev = &mhi_cntrl->mhi_dev->dev;
+	struct device *dev = &mhi_chan->mhi_dev->dev;
+	enum mhi_cmd_type cmd = MHI_CMD_NOP;
+	int ret = -EIO;
+
+	dev_dbg(dev, "%d: Updating channel state to: %s\n", mhi_chan->chan,
+		TO_CH_STATE_TYPE_STR(to_state));
+
+	switch (to_state) {
+	case MHI_CH_STATE_TYPE_RESET:
+		write_lock_irq(&mhi_chan->lock);
+		if (mhi_chan->ch_state != MHI_CH_STATE_STOP &&
+		    mhi_chan->ch_state != MHI_CH_STATE_ENABLED &&
+		    mhi_chan->ch_state != MHI_CH_STATE_SUSPENDED) {
+			write_unlock_irq(&mhi_chan->lock);
+			return -EINVAL;
+		}
+		mhi_chan->ch_state = MHI_CH_STATE_DISABLED;
+		write_unlock_irq(&mhi_chan->lock);
 
-	dev_dbg(dev, "Entered: unprepare channel:%d\n", mhi_chan->chan);
+		cmd = MHI_CMD_RESET_CHAN;
+		break;
+	case MHI_CH_STATE_TYPE_STOP:
+		if (mhi_chan->ch_state != MHI_CH_STATE_ENABLED)
+			return -EINVAL;
 
-	/* no more processing events for this channel */
-	mutex_lock(&mhi_chan->mutex);
-	write_lock_irq(&mhi_chan->lock);
-	if (mhi_chan->ch_state != MHI_CH_STATE_ENABLED &&
-	    mhi_chan->ch_state != MHI_CH_STATE_SUSPENDED) {
-		write_unlock_irq(&mhi_chan->lock);
-		mutex_unlock(&mhi_chan->mutex);
-		return;
+		cmd = MHI_CMD_STOP_CHAN;
+		break;
+	case MHI_CH_STATE_TYPE_START:
+		if (mhi_chan->ch_state != MHI_CH_STATE_STOP &&
+		    mhi_chan->ch_state != MHI_CH_STATE_DISABLED)
+			return -EINVAL;
+
+		cmd = MHI_CMD_START_CHAN;
+		break;
+	default:
+		dev_err(dev, "%d: Channel state update to %s not allowed\n",
+			mhi_chan->chan, TO_CH_STATE_TYPE_STR(to_state));
+		return -EINVAL;
 	}
 
-	mhi_chan->ch_state = MHI_CH_STATE_DISABLED;
-	write_unlock_irq(&mhi_chan->lock);
+	/* bring host and device out of suspended states */
+	ret = mhi_device_get_sync(mhi_cntrl->mhi_dev);
+	if (ret)
+		return ret;
+	mhi_cntrl->runtime_get(mhi_cntrl);
 
 	reinit_completion(&mhi_chan->completion);
-	read_lock_bh(&mhi_cntrl->pm_lock);
-	if (MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state)) {
-		read_unlock_bh(&mhi_cntrl->pm_lock);
-		goto error_invalid_state;
+	ret = mhi_send_cmd(mhi_cntrl, mhi_chan, cmd);
+	if (ret) {
+		dev_err(dev, "%d: Failed to send %s channel command\n",
+			mhi_chan->chan, TO_CH_STATE_TYPE_STR(to_state));
+		goto exit_channel_update;
 	}
 
-	mhi_cntrl->wake_toggle(mhi_cntrl);
-	read_unlock_bh(&mhi_cntrl->pm_lock);
+	ret = wait_for_completion_timeout(&mhi_chan->completion,
+				       msecs_to_jiffies(mhi_cntrl->timeout_ms));
+	if (!ret || mhi_chan->ccs != MHI_EV_CC_SUCCESS) {
+		dev_err(dev,
+			"%d: Failed to receive %s channel command completion\n",
+			mhi_chan->chan, TO_CH_STATE_TYPE_STR(to_state));
+		ret = -EIO;
+		goto exit_channel_update;
+	}
 
-	mhi_cntrl->runtime_get(mhi_cntrl);
+	ret = 0;
+
+	if (to_state != MHI_CH_STATE_TYPE_RESET) {
+		write_lock_irq(&mhi_chan->lock);
+		mhi_chan->ch_state = (to_state == MHI_CH_STATE_TYPE_START) ?
+				      MHI_CH_STATE_ENABLED : MHI_CH_STATE_STOP;
+		write_unlock_irq(&mhi_chan->lock);
+	}
+
+	dev_dbg(dev, "%d: Channel state change to %s successful\n",
+		mhi_chan->chan, TO_CH_STATE_TYPE_STR(to_state));
+
+exit_channel_update:
 	mhi_cntrl->runtime_put(mhi_cntrl);
-	ret = mhi_send_cmd(mhi_cntrl, mhi_chan, MHI_CMD_RESET_CHAN);
-	if (ret)
-		goto error_invalid_state;
+	mhi_device_put(mhi_cntrl->mhi_dev);
 
-	/* even if it fails we will still reset */
-	ret = wait_for_completion_timeout(&mhi_chan->completion,
-				msecs_to_jiffies(mhi_cntrl->timeout_ms));
-	if (!ret || mhi_chan->ccs != MHI_EV_CC_SUCCESS)
-		dev_err(dev,
-			"Failed to receive cmd completion, still resetting\n");
+	return ret;
+}
+
+static void __mhi_unprepare_channel(struct mhi_controller *mhi_cntrl,
+				    struct mhi_chan *mhi_chan)
+{
+	int ret;
+	struct device *dev = &mhi_chan->mhi_dev->dev;
+
+	mutex_lock(&mhi_chan->mutex);
+
+	/* no more processing events for this channel */
+	ret = mhi_update_channel_state(mhi_cntrl, mhi_chan,
+				       MHI_CH_STATE_TYPE_RESET);
+	if (ret)
+		dev_err(dev, "%d: Failed to reset channel, still resetting\n",
+			mhi_chan->chan);
 
-error_invalid_state:
 	if (!mhi_chan->offload_ch) {
 		mhi_reset_chan(mhi_cntrl, mhi_chan);
 		mhi_deinit_chan_ctxt(mhi_cntrl, mhi_chan);
 	}
-	dev_dbg(dev, "chan:%d successfully resetted\n", mhi_chan->chan);
+	dev_dbg(dev, "%d: successfully reset\n", mhi_chan->chan);
+
 	mutex_unlock(&mhi_chan->mutex);
 }
 

@@ -1245,28 +1303,16 @@ int mhi_prepare_channel(struct mhi_controller *mhi_cntrl,
 			struct mhi_chan *mhi_chan)
 {
 	int ret = 0;
-	struct device *dev = &mhi_cntrl->mhi_dev->dev;
-
-	dev_dbg(dev, "Preparing channel: %d\n", mhi_chan->chan);
+	struct device *dev = &mhi_chan->mhi_dev->dev;
 
 	if (!(BIT(mhi_cntrl->ee) & mhi_chan->ee_mask)) {
-		dev_err(dev,
-			"Current EE: %s Required EE Mask: 0x%x for chan: %s\n",
-			TO_MHI_EXEC_STR(mhi_cntrl->ee), mhi_chan->ee_mask,
-			mhi_chan->name);
+		dev_err(dev, "Current EE: %s Required EE Mask: 0x%x\n",
+			TO_MHI_EXEC_STR(mhi_cntrl->ee), mhi_chan->ee_mask);
 		return -ENOTCONN;
 	}
 
 	mutex_lock(&mhi_chan->mutex);
 
-	/* If channel is not in disable state, do not allow it to start */
-	if (mhi_chan->ch_state != MHI_CH_STATE_DISABLED) {
-		ret = -EIO;
-		dev_dbg(dev, "channel: %d is not in disabled state\n",
-			mhi_chan->chan);
-		goto error_init_chan;
-	}
-
 	/* Check of client manages channel context for offload channels */
 	if (!mhi_chan->offload_ch) {
 		ret = mhi_init_chan_ctxt(mhi_cntrl, mhi_chan);

@@ -1274,34 +1320,11 @@ int mhi_prepare_channel(struct mhi_controller *mhi_cntrl,
 			goto error_init_chan;
 	}
 
-	reinit_completion(&mhi_chan->completion);
-	read_lock_bh(&mhi_cntrl->pm_lock);
-	if (MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state)) {
-		read_unlock_bh(&mhi_cntrl->pm_lock);
-		ret = -EIO;
-		goto error_pm_state;
-	}
-
-	mhi_cntrl->wake_toggle(mhi_cntrl);
-	read_unlock_bh(&mhi_cntrl->pm_lock);
-	mhi_cntrl->runtime_get(mhi_cntrl);
-	mhi_cntrl->runtime_put(mhi_cntrl);
-
-	ret = mhi_send_cmd(mhi_cntrl, mhi_chan, MHI_CMD_START_CHAN);
+	ret = mhi_update_channel_state(mhi_cntrl, mhi_chan,
+				       MHI_CH_STATE_TYPE_START);
 	if (ret)
 		goto error_pm_state;
 
-	ret = wait_for_completion_timeout(&mhi_chan->completion,
-				msecs_to_jiffies(mhi_cntrl->timeout_ms));
-	if (!ret || mhi_chan->ccs != MHI_EV_CC_SUCCESS) {
-		ret = -EIO;
-		goto error_pm_state;
-	}
-
-	write_lock_irq(&mhi_chan->lock);
-	mhi_chan->ch_state = MHI_CH_STATE_ENABLED;
-	write_unlock_irq(&mhi_chan->lock);
-
 	/* Pre-allocate buffer for xfer ring */
 	if (mhi_chan->pre_alloc) {
 		int nr_el = get_nr_avail_ring_elements(mhi_cntrl,

@@ -1339,9 +1362,6 @@ int mhi_prepare_channel(struct mhi_controller *mhi_cntrl,
 
 	mutex_unlock(&mhi_chan->mutex);
 
-	dev_dbg(dev, "Chan: %d successfully moved to start state\n",
-		mhi_chan->chan);
-
 	return 0;
 
 error_pm_state:

Signature · 2 lines

The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

Quoted 9 lines · Bhaumik Bhatt

Improve the channel handling state machine such that all commands go through a common function and validation process to ensure that the state machine is not violated in any way and adheres to the MHI specification. Assert device wake before sending the channel update commands instead of a wake toggle to ensure we fail if device is in a bad state. Also update print messages to use client device to accurately represent the channel being updated.

This patch is doing atleast 3 things and that is not acceptable. Please split this patch and send.

Thanks,
Mani

Quoted 285 lines

Signed-off-by Bhaumik Bhatt <[email protected]>

Reviewed-by Hemant Kumar <[email protected]>

---
 drivers/bus/mhi/core/init.c     |   6 ++
 drivers/bus/mhi/core/internal.h |  12 +++
 drivers/bus/mhi/core/main.c     | 172 
++++++++++++++++++++++------------------
 3 files changed, 114 insertions(+), 76 deletions(-)

drivers/bus/mhi/core/init.c +6 -0

index 03c5786..482b365 100644
@@ -54,6 +54,12 @@ const char * const mhi_state_str[MHI_STATE_MAX] = {
 	[MHI_STATE_SYS_ERR] = "SYS_ERR",
 };
 
+const char * const mhi_ch_state_type_str[MHI_CH_STATE_TYPE_MAX] = {
+	[MHI_CH_STATE_TYPE_RESET] = "RESET",
+	[MHI_CH_STATE_TYPE_STOP] = "STOP",
+	[MHI_CH_STATE_TYPE_START] = "START",
+};
+
 static const char * const mhi_pm_state_str[] = {
 	[MHI_PM_STATE_DISABLE] = "DISABLE",
 	[MHI_PM_STATE_POR] = "POR",

drivers/bus/mhi/core/internal.h +12 -0

index 6f80ec3..7e3aac1 100644
@@ -369,6 +369,18 @@ enum mhi_ch_state {
 	MHI_CH_STATE_ERROR = 0x5,
 };
 
+enum mhi_ch_state_type {
+	MHI_CH_STATE_TYPE_RESET,
+	MHI_CH_STATE_TYPE_STOP,
+	MHI_CH_STATE_TYPE_START,
+	MHI_CH_STATE_TYPE_MAX,
+};
+
+extern const char * const 
 mhi_ch_state_type_str[MHI_CH_STATE_TYPE_MAX];
+#define TO_CH_STATE_TYPE_STR(state) (((state) >= 
 MHI_CH_STATE_TYPE_MAX) ? \
+				     "INVALID_STATE" : \
+				     mhi_ch_state_type_str[(state)])
+
 #define MHI_INVALID_BRSTMODE(mode) (mode != MHI_DB_BRST_DISABLE && \

drivers/bus/mhi/core/internal.h +0 -0

 				    mode != MHI_DB_BRST_ENABLE)

drivers/bus/mhi/core/main.c +94 -48

index d068188..2f6fdb2 100644
@@ -1188,56 +1188,114 @@ int mhi_send_cmd(struct mhi_controller 
 *mhi_cntrl,
 	return 0;
 }
 
-static void __mhi_unprepare_channel(struct mhi_controller *mhi_cntrl,
-				    struct mhi_chan *mhi_chan)
+static int mhi_update_channel_state(struct mhi_controller *mhi_cntrl,
+				    struct mhi_chan *mhi_chan,
+				    enum mhi_ch_state_type to_state)
 {
-	int ret;
-	struct device *dev = &mhi_cntrl->mhi_dev->dev;
+	struct device *dev = &mhi_chan->mhi_dev->dev;
+	enum mhi_cmd_type cmd = MHI_CMD_NOP;
+	int ret = -EIO;
+
+	dev_dbg(dev, "%d: Updating channel state to: %s\n", mhi_chan->chan,
+		TO_CH_STATE_TYPE_STR(to_state));
+
+	switch (to_state) {
+	case MHI_CH_STATE_TYPE_RESET:
+		write_lock_irq(&mhi_chan->lock);
+		if (mhi_chan->ch_state != MHI_CH_STATE_STOP &&
+		    mhi_chan->ch_state != MHI_CH_STATE_ENABLED &&
+		    mhi_chan->ch_state != MHI_CH_STATE_SUSPENDED) {
+			write_unlock_irq(&mhi_chan->lock);
+			return -EINVAL;
+		}
+		mhi_chan->ch_state = MHI_CH_STATE_DISABLED;
+		write_unlock_irq(&mhi_chan->lock);
 
-	dev_dbg(dev, "Entered: unprepare channel:%d\n", mhi_chan->chan);
+		cmd = MHI_CMD_RESET_CHAN;
+		break;
+	case MHI_CH_STATE_TYPE_STOP:
+		if (mhi_chan->ch_state != MHI_CH_STATE_ENABLED)
+			return -EINVAL;
 
-	/* no more processing events for this channel */
-	mutex_lock(&mhi_chan->mutex);
-	write_lock_irq(&mhi_chan->lock);
-	if (mhi_chan->ch_state != MHI_CH_STATE_ENABLED &&
-	    mhi_chan->ch_state != MHI_CH_STATE_SUSPENDED) {
-		write_unlock_irq(&mhi_chan->lock);
-		mutex_unlock(&mhi_chan->mutex);
-		return;
+		cmd = MHI_CMD_STOP_CHAN;
+		break;
+	case MHI_CH_STATE_TYPE_START:
+		if (mhi_chan->ch_state != MHI_CH_STATE_STOP &&
+		    mhi_chan->ch_state != MHI_CH_STATE_DISABLED)
+			return -EINVAL;
+
+		cmd = MHI_CMD_START_CHAN;
+		break;
+	default:
+		dev_err(dev, "%d: Channel state update to %s not allowed\n",
+			mhi_chan->chan, TO_CH_STATE_TYPE_STR(to_state));
+		return -EINVAL;
 	}
 
-	mhi_chan->ch_state = MHI_CH_STATE_DISABLED;
-	write_unlock_irq(&mhi_chan->lock);
+	/* bring host and device out of suspended states */
+	ret = mhi_device_get_sync(mhi_cntrl->mhi_dev);
+	if (ret)
+		return ret;
+	mhi_cntrl->runtime_get(mhi_cntrl);
 
 	reinit_completion(&mhi_chan->completion);
-	read_lock_bh(&mhi_cntrl->pm_lock);
-	if (MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state)) {
-		read_unlock_bh(&mhi_cntrl->pm_lock);
-		goto error_invalid_state;
+	ret = mhi_send_cmd(mhi_cntrl, mhi_chan, cmd);
+	if (ret) {
+		dev_err(dev, "%d: Failed to send %s channel command\n",
+			mhi_chan->chan, TO_CH_STATE_TYPE_STR(to_state));
+		goto exit_channel_update;
 	}
 
-	mhi_cntrl->wake_toggle(mhi_cntrl);
-	read_unlock_bh(&mhi_cntrl->pm_lock);
+	ret = wait_for_completion_timeout(&mhi_chan->completion,
+				       msecs_to_jiffies(mhi_cntrl->timeout_ms));
+	if (!ret || mhi_chan->ccs != MHI_EV_CC_SUCCESS) {
+		dev_err(dev,
+			"%d: Failed to receive %s channel command completion\n",
+			mhi_chan->chan, TO_CH_STATE_TYPE_STR(to_state));
+		ret = -EIO;
+		goto exit_channel_update;
+	}
 
-	mhi_cntrl->runtime_get(mhi_cntrl);
+	ret = 0;
+
+	if (to_state != MHI_CH_STATE_TYPE_RESET) {
+		write_lock_irq(&mhi_chan->lock);
+		mhi_chan->ch_state = (to_state == MHI_CH_STATE_TYPE_START) ?
+				      MHI_CH_STATE_ENABLED : MHI_CH_STATE_STOP;
+		write_unlock_irq(&mhi_chan->lock);
+	}
+
+	dev_dbg(dev, "%d: Channel state change to %s successful\n",
+		mhi_chan->chan, TO_CH_STATE_TYPE_STR(to_state));
+
+exit_channel_update:
 	mhi_cntrl->runtime_put(mhi_cntrl);
-	ret = mhi_send_cmd(mhi_cntrl, mhi_chan, MHI_CMD_RESET_CHAN);
-	if (ret)
-		goto error_invalid_state;
+	mhi_device_put(mhi_cntrl->mhi_dev);
 
-	/* even if it fails we will still reset */
-	ret = wait_for_completion_timeout(&mhi_chan->completion,
-				msecs_to_jiffies(mhi_cntrl->timeout_ms));
-	if (!ret || mhi_chan->ccs != MHI_EV_CC_SUCCESS)
-		dev_err(dev,
-			"Failed to receive cmd completion, still resetting\n");
+	return ret;
+}
+
+static void __mhi_unprepare_channel(struct mhi_controller *mhi_cntrl,
+				    struct mhi_chan *mhi_chan)
+{
+	int ret;
+	struct device *dev = &mhi_chan->mhi_dev->dev;
+
+	mutex_lock(&mhi_chan->mutex);
+
+	/* no more processing events for this channel */
+	ret = mhi_update_channel_state(mhi_cntrl, mhi_chan,
+				       MHI_CH_STATE_TYPE_RESET);
+	if (ret)
+		dev_err(dev, "%d: Failed to reset channel, still resetting\n",
+			mhi_chan->chan);
 
-error_invalid_state:
 	if (!mhi_chan->offload_ch) {
 		mhi_reset_chan(mhi_cntrl, mhi_chan);
 		mhi_deinit_chan_ctxt(mhi_cntrl, mhi_chan);
 	}
-	dev_dbg(dev, "chan:%d successfully resetted\n", mhi_chan->chan);
+	dev_dbg(dev, "%d: successfully reset\n", mhi_chan->chan);
+
 	mutex_unlock(&mhi_chan->mutex);
 }

@@ -1245,28 +1303,16 @@ int mhi_prepare_channel(struct mhi_controller 
 *mhi_cntrl,
 			struct mhi_chan *mhi_chan)
 {
 	int ret = 0;
-	struct device *dev = &mhi_cntrl->mhi_dev->dev;
-
-	dev_dbg(dev, "Preparing channel: %d\n", mhi_chan->chan);
+	struct device *dev = &mhi_chan->mhi_dev->dev;
 
 	if (!(BIT(mhi_cntrl->ee) & mhi_chan->ee_mask)) {
-		dev_err(dev,
-			"Current EE: %s Required EE Mask: 0x%x for chan: %s\n",
-			TO_MHI_EXEC_STR(mhi_cntrl->ee), mhi_chan->ee_mask,
-			mhi_chan->name);
+		dev_err(dev, "Current EE: %s Required EE Mask: 0x%x\n",
+			TO_MHI_EXEC_STR(mhi_cntrl->ee), mhi_chan->ee_mask);
 		return -ENOTCONN;
 	}
 
 	mutex_lock(&mhi_chan->mutex);
 
-	/* If channel is not in disable state, do not allow it to start */
-	if (mhi_chan->ch_state != MHI_CH_STATE_DISABLED) {
-		ret = -EIO;
-		dev_dbg(dev, "channel: %d is not in disabled state\n",
-			mhi_chan->chan);
-		goto error_init_chan;
-	}
-
 	/* Check of client manages channel context for offload channels */
 	if (!mhi_chan->offload_ch) {

drivers/bus/mhi/core/main.c +2 -25

 		ret = mhi_init_chan_ctxt(mhi_cntrl, mhi_chan);

@@ -1274,34 +1320,11 @@ int mhi_prepare_channel(struct mhi_controller 
 *mhi_cntrl,
 			goto error_init_chan;
 	}
 
-	reinit_completion(&mhi_chan->completion);
-	read_lock_bh(&mhi_cntrl->pm_lock);
-	if (MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state)) {
-		read_unlock_bh(&mhi_cntrl->pm_lock);
-		ret = -EIO;
-		goto error_pm_state;
-	}
-
-	mhi_cntrl->wake_toggle(mhi_cntrl);
-	read_unlock_bh(&mhi_cntrl->pm_lock);
-	mhi_cntrl->runtime_get(mhi_cntrl);
-	mhi_cntrl->runtime_put(mhi_cntrl);
-
-	ret = mhi_send_cmd(mhi_cntrl, mhi_chan, MHI_CMD_START_CHAN);
+	ret = mhi_update_channel_state(mhi_cntrl, mhi_chan,
+				       MHI_CH_STATE_TYPE_START);
 	if (ret)
 		goto error_pm_state;
 
-	ret = wait_for_completion_timeout(&mhi_chan->completion,
-				msecs_to_jiffies(mhi_cntrl->timeout_ms));
-	if (!ret || mhi_chan->ccs != MHI_EV_CC_SUCCESS) {
-		ret = -EIO;
-		goto error_pm_state;
-	}
-
-	write_lock_irq(&mhi_chan->lock);
-	mhi_chan->ch_state = MHI_CH_STATE_ENABLED;
-	write_unlock_irq(&mhi_chan->lock);
-
 	/* Pre-allocate buffer for xfer ring */
 	if (mhi_chan->pre_alloc) {

drivers/bus/mhi/core/main.c +0 -3

 		int nr_el = get_nr_avail_ring_elements(mhi_cntrl,

@@ -1339,9 +1362,6 @@ int mhi_prepare_channel(struct mhi_controller 
 *mhi_cntrl,
 
 	mutex_unlock(&mhi_chan->mutex);
 
-	dev_dbg(dev, "Chan: %d successfully moved to start state\n",
-		mhi_chan->chan);
-
 	return 0;
 

Quoted 5 lines

error_pm_state:
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project

A client can attempt to unprepare certain channels for transfer even after the execution environment they are supposed to run in has changed. In the event that happens, the device need not be notified of the reset and the host can proceed with clean up for the channel context and memory allocated for it on the host as the device will no longer be able to respond to such a request.

Signed-off-by Bhaumik Bhatt <[email protected]>

Reviewed-by Hemant Kumar <[email protected]>

---
 drivers/bus/mhi/core/main.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

drivers/bus/mhi/core/main.c +11 -0

index 2f6fdb2..f511e3a 100644
@@ -1283,6 +1283,12 @@ static void __mhi_unprepare_channel(struct mhi_controller *mhi_cntrl,
 
 	mutex_lock(&mhi_chan->mutex);
 
+	if (!(BIT(mhi_cntrl->ee) & mhi_chan->ee_mask)) {
+		dev_dbg(dev, "Current EE: %s Required EE Mask: 0x%x\n",
+			TO_MHI_EXEC_STR(mhi_cntrl->ee), mhi_chan->ee_mask);
+		goto exit_unprepare_channel;
+	}
+
 	/* no more processing events for this channel */
 	ret = mhi_update_channel_state(mhi_cntrl, mhi_chan,
 				       MHI_CH_STATE_TYPE_RESET);

@@ -1290,6 +1296,11 @@ static void __mhi_unprepare_channel(struct mhi_controller *mhi_cntrl,
 		dev_err(dev, "%d: Failed to reset channel, still resetting\n",
 			mhi_chan->chan);
 
+exit_unprepare_channel:
+	write_lock_irq(&mhi_chan->lock);
+	mhi_chan->ch_state = MHI_CH_STATE_DISABLED;
+	write_unlock_irq(&mhi_chan->lock);
+
 	if (!mhi_chan->offload_ch) {
 		mhi_reset_chan(mhi_cntrl, mhi_chan);
 		mhi_deinit_chan_ctxt(mhi_cntrl, mhi_chan);

Signature · 2 lines

The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

The mhi_prepare_for_transfer() and mhi_unprepare_from_transfer() APIs could use better explanation. Add details on what MHI does when these APIs are used.

Signed-off-by Bhaumik Bhatt <[email protected]>

Reviewed-by Hemant Kumar <[email protected]>

---
 include/linux/mhi.h | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

include/linux/mhi.h +16 -2

index d26acc8..56c4c52 100644
@@ -712,13 +712,27 @@ int mhi_device_get_sync(struct mhi_device *mhi_dev);
 void mhi_device_put(struct mhi_device *mhi_dev);
 
 /**
- * mhi_prepare_for_transfer - Setup channel for data transfer
+ * mhi_prepare_for_transfer - Setup UL and DL channels for data transfer.
+ *                            Allocate and initialize the channel context and
+ *                            also issue the START channel command to both
+ *                            channels. Channels can be started only if both
+ *                            host and device execution environments match and
+ *                            channels are in a DISABLED state.
  * @mhi_dev: Device associated with the channels
  */
 int mhi_prepare_for_transfer(struct mhi_device *mhi_dev);
 
 /**
- * mhi_unprepare_from_transfer - Unprepare the channels
+ * mhi_unprepare_from_transfer - Reset UL and DL channels for data transfer.
+ *                               Issue the RESET channel command and let the
+ *                               device clean-up the context so no incoming
+ *                               transfers are seen on the host. Free memory
+ *                               associated with the context on host. If device
+ *                               is unresponsive, only perform a host side
+ *                               clean-up. Channels can be reset only if both
+ *                               host and device execution environments match
+ *                               and channels are in an ENABLED, STOPPED or
+ *                               SUSPENDED state.
  * @mhi_dev: Device associated with the channels
  */
 void mhi_unprepare_from_transfer(struct mhi_device *mhi_dev);

Signature · 2 lines

The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

Clearing a channel context can happen twice if the client driver unprepares and reset the channels from the remove() callback from a controller requested MHI power down sequence. If there are multiple attempts at calling the mhi_free_coherent() API, we see kernel warnings such as "trying to free invalid coherent area". Example for one such client is the QRTR MHI driver. Avoid these warnings by skipping mhi_deinit_chan_ctxt() API call and prevent extra work from MHI as the channels are already disabled.

Signed-off-by Bhaumik Bhatt <[email protected]>

Clearing a channel context can happen twice if the client driver unprepares and reset the channels from the remove() callback from a controller requested MHI power down sequence. If there are multiple attempts at calling the mhi_free_coherent() API, we see kernel warnings such as "trying to free invalid coherent area". Example for one such client is the QRTR MHI driver. Avoid these warnings by skipping mhi_deinit_chan_ctxt() API call and prevent extra work from MHI as the channels are already disabled.

Signed-off-by Bhaumik Bhatt <[email protected]>

---
 drivers/bus/mhi/core/init.c | 1 +
 1 file changed, 1 insertion(+)

drivers/bus/mhi/core/init.c +1 -0

index 30eef19..272f350 100644
@@ -1314,6 +1314,7 @@ static int mhi_driver_remove(struct device *dev)
 
 		if ((ch_state[dir] == MHI_CH_STATE_ENABLED ||
 		     ch_state[dir] == MHI_CH_STATE_STOP) &&
+		    mhi_chan->ch_state != MHI_CH_STATE_DISABLED &&
 		    !mhi_chan->offload_ch)
 			mhi_deinit_chan_ctxt(mhi_cntrl, mhi_chan);
 

Signature · 2 lines

The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

Quoted 9 lines · Bhaumik Bhatt

Clearing a channel context can happen twice if the client driver unprepares and reset the channels from the remove() callback from a controller requested MHI power down sequence. If there are multiple attempts at calling the mhi_free_coherent() API, we see kernel warnings such as "trying to free invalid coherent area". Example for one such client is the QRTR MHI driver. Avoid these warnings by skipping mhi_deinit_chan_ctxt() API call and prevent extra work from MHI as the channels are already disabled.

Quoted 1 line

Signed-off-by Bhaumik Bhatt <[email protected]>

Is this patch still valid? We merged a similar fix from Loic for v5.11.

Thanks,
Mani

Quoted 16 lines

---
 drivers/bus/mhi/core/init.c | 1 +
 1 file changed, 1 insertion(+)

drivers/bus/mhi/core/init.c +1 -0

index 30eef19..272f350 100644
@@ -1314,6 +1314,7 @@ static int mhi_driver_remove(struct device *dev)
 
 		if ((ch_state[dir] == MHI_CH_STATE_ENABLED ||
 		     ch_state[dir] == MHI_CH_STATE_STOP) &&
+		    mhi_chan->ch_state != MHI_CH_STATE_DISABLED &&
 		    !mhi_chan->offload_ch)
 			mhi_deinit_chan_ctxt(mhi_cntrl, mhi_chan);
 

Quoted 4 lines

--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project