[v6,3/4] bus: mhi: core: Process execution environment changes serially
diff mbox series

Message ID 1614208985-20851-4-git-send-email-bbhatt@codeaurora.org
State In Next
Commit ef2126c4e2ea2b92f543fae00a2a0332e4573c48
Headers show
Series
  • Serialize execution environment changes for MHI
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Commit Message

Bhaumik Bhatt Feb. 24, 2021, 11:23 p.m. UTC
In current design, whenever the BHI interrupt is fired, the
execution environment is updated. This can cause race conditions
and impede ongoing power up/down processing. For example, if a
power down is in progress, MHI host updates to a local "disabled"
execution environment. If a BHI interrupt fires later, that value
gets replaced with one from the BHI EE register. This impacts the
controller as it does not expect multiple RDDM execution
environment change status callbacks as an example. Another issue
would be that the device can enter mission mode and the execution
environment is updated, while device creation for SBL channels is
still going on due to slower PM state worker thread run, leading
to multiple attempts at opening the same channel.

Ensure that EE changes are handled only from appropriate places
and occur one after another and handle only PBL modes or RDDM EE
changes as critical events directly from the interrupt handler.
Simplify handling by waiting for SYS ERROR before handling RDDM.
This also makes sure that we use the correct execution environment
to notify the controller driver when the device resets to one of
the PBL execution environments.

Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org>
---
 drivers/bus/mhi/core/main.c | 40 +++++++++++++++++++++-------------------
 drivers/bus/mhi/core/pm.c   |  7 ++++---
 2 files changed, 25 insertions(+), 22 deletions(-)

Comments

Loic Poulain March 4, 2021, 8:43 a.m. UTC | #1
On Thu, 25 Feb 2021 at 00:23, Bhaumik Bhatt <bbhatt@codeaurora.org> wrote:
>
> In current design, whenever the BHI interrupt is fired, the
> execution environment is updated. This can cause race conditions
> and impede ongoing power up/down processing. For example, if a
> power down is in progress, MHI host updates to a local "disabled"
> execution environment. If a BHI interrupt fires later, that value
> gets replaced with one from the BHI EE register. This impacts the
> controller as it does not expect multiple RDDM execution
> environment change status callbacks as an example. Another issue
> would be that the device can enter mission mode and the execution
> environment is updated, while device creation for SBL channels is
> still going on due to slower PM state worker thread run, leading
> to multiple attempts at opening the same channel.
>
> Ensure that EE changes are handled only from appropriate places
> and occur one after another and handle only PBL modes or RDDM EE
> changes as critical events directly from the interrupt handler.
> Simplify handling by waiting for SYS ERROR before handling RDDM.
> This also makes sure that we use the correct execution environment
> to notify the controller driver when the device resets to one of
> the PBL execution environments.
>
> Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org>

Looking good now

Reviewed-by: Loic Poulain <loic.poulain@linaro.org>
Manivannan Sadhasivam March 10, 2021, 2:04 p.m. UTC | #2
On Wed, Feb 24, 2021 at 03:23:04PM -0800, Bhaumik Bhatt wrote:
> In current design, whenever the BHI interrupt is fired, the
> execution environment is updated. This can cause race conditions
> and impede ongoing power up/down processing. For example, if a
> power down is in progress, MHI host updates to a local "disabled"
> execution environment. If a BHI interrupt fires later, that value
> gets replaced with one from the BHI EE register. This impacts the
> controller as it does not expect multiple RDDM execution
> environment change status callbacks as an example. Another issue
> would be that the device can enter mission mode and the execution
> environment is updated, while device creation for SBL channels is
> still going on due to slower PM state worker thread run, leading
> to multiple attempts at opening the same channel.
> 
> Ensure that EE changes are handled only from appropriate places
> and occur one after another and handle only PBL modes or RDDM EE
> changes as critical events directly from the interrupt handler.
> Simplify handling by waiting for SYS ERROR before handling RDDM.
> This also makes sure that we use the correct execution environment
> to notify the controller driver when the device resets to one of
> the PBL execution environments.
> 
> Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org>

Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

Thanks,
Mani

> ---
>  drivers/bus/mhi/core/main.c | 40 +++++++++++++++++++++-------------------
>  drivers/bus/mhi/core/pm.c   |  7 ++++---
>  2 files changed, 25 insertions(+), 22 deletions(-)
> 
> diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
> index 7a2e98c..9715f51 100644
> --- a/drivers/bus/mhi/core/main.c
> +++ b/drivers/bus/mhi/core/main.c
> @@ -430,7 +430,7 @@ irqreturn_t mhi_intvec_threaded_handler(int irq_number, void *priv)
>  	struct device *dev = &mhi_cntrl->mhi_dev->dev;
>  	enum mhi_state state = MHI_STATE_MAX;
>  	enum mhi_pm_state pm_state = 0;
> -	enum mhi_ee_type ee = 0;
> +	enum mhi_ee_type ee = MHI_EE_MAX;
>  
>  	write_lock_irq(&mhi_cntrl->pm_lock);
>  	if (!MHI_REG_ACCESS_VALID(mhi_cntrl->pm_state)) {
> @@ -439,8 +439,7 @@ irqreturn_t mhi_intvec_threaded_handler(int irq_number, void *priv)
>  	}
>  
>  	state = mhi_get_mhi_state(mhi_cntrl);
> -	ee = mhi_cntrl->ee;
> -	mhi_cntrl->ee = mhi_get_exec_env(mhi_cntrl);
> +	ee = mhi_get_exec_env(mhi_cntrl);
>  	dev_dbg(dev, "local ee:%s device ee:%s dev_state:%s\n",
>  		TO_MHI_EXEC_STR(mhi_cntrl->ee), TO_MHI_EXEC_STR(ee),
>  		TO_MHI_STATE_STR(state));
> @@ -452,27 +451,30 @@ irqreturn_t mhi_intvec_threaded_handler(int irq_number, void *priv)
>  	}
>  	write_unlock_irq(&mhi_cntrl->pm_lock);
>  
> -	 /* If device supports RDDM don't bother processing SYS error */
> -	if (mhi_cntrl->rddm_image) {
> -		/* host may be performing a device power down already */
> -		if (!mhi_is_active(mhi_cntrl))
> -			goto exit_intvec;
> +	if (pm_state != MHI_PM_SYS_ERR_DETECT || ee == mhi_cntrl->ee)
> +		goto exit_intvec;
>  
> -		if (mhi_cntrl->ee == MHI_EE_RDDM && mhi_cntrl->ee != ee) {
> +	switch (ee) {
> +	case MHI_EE_RDDM:
> +		/* proceed if power down is not already in progress */
> +		if (mhi_cntrl->rddm_image && mhi_is_active(mhi_cntrl)) {
>  			mhi_cntrl->status_cb(mhi_cntrl, MHI_CB_EE_RDDM);
> +			mhi_cntrl->ee = ee;
>  			wake_up_all(&mhi_cntrl->state_event);
>  		}
> -		goto exit_intvec;
> -	}
> -
> -	if (pm_state == MHI_PM_SYS_ERR_DETECT) {
> +		break;
> +	case MHI_EE_PBL:
> +	case MHI_EE_EDL:
> +	case MHI_EE_PTHRU:
> +		mhi_cntrl->status_cb(mhi_cntrl, MHI_CB_FATAL_ERROR);
> +		mhi_cntrl->ee = ee;
>  		wake_up_all(&mhi_cntrl->state_event);
> -
> -		/* For fatal errors, we let controller decide next step */
> -		if (MHI_IN_PBL(ee))
> -			mhi_cntrl->status_cb(mhi_cntrl, MHI_CB_FATAL_ERROR);
> -		else
> -			mhi_pm_sys_err_handler(mhi_cntrl);
> +		mhi_pm_sys_err_handler(mhi_cntrl);
> +		break;
> +	default:
> +		wake_up_all(&mhi_cntrl->state_event);
> +		mhi_pm_sys_err_handler(mhi_cntrl);
> +		break;
>  	}
>  
>  exit_intvec:
> diff --git a/drivers/bus/mhi/core/pm.c b/drivers/bus/mhi/core/pm.c
> index c09ec13..c870fa8 100644
> --- a/drivers/bus/mhi/core/pm.c
> +++ b/drivers/bus/mhi/core/pm.c
> @@ -377,21 +377,22 @@ static int mhi_pm_mission_mode_transition(struct mhi_controller *mhi_cntrl)
>  {
>  	struct mhi_event *mhi_event;
>  	struct device *dev = &mhi_cntrl->mhi_dev->dev;
> -	enum mhi_ee_type current_ee = mhi_cntrl->ee;
> +	enum mhi_ee_type ee = MHI_EE_MAX, current_ee = mhi_cntrl->ee;
>  	int i, ret;
>  
>  	dev_dbg(dev, "Processing Mission Mode transition\n");
>  
>  	write_lock_irq(&mhi_cntrl->pm_lock);
>  	if (MHI_REG_ACCESS_VALID(mhi_cntrl->pm_state))
> -		mhi_cntrl->ee = mhi_get_exec_env(mhi_cntrl);
> +		ee = mhi_get_exec_env(mhi_cntrl);
>  
> -	if (!MHI_IN_MISSION_MODE(mhi_cntrl->ee)) {
> +	if (!MHI_IN_MISSION_MODE(ee)) {
>  		mhi_cntrl->pm_state = MHI_PM_LD_ERR_FATAL_DETECT;
>  		write_unlock_irq(&mhi_cntrl->pm_lock);
>  		wake_up_all(&mhi_cntrl->state_event);
>  		return -EIO;
>  	}
> +	mhi_cntrl->ee = ee;
>  	write_unlock_irq(&mhi_cntrl->pm_lock);
>  
>  	wake_up_all(&mhi_cntrl->state_event);
> -- 
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>

Patch
diff mbox series

diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
index 7a2e98c..9715f51 100644
--- a/drivers/bus/mhi/core/main.c
+++ b/drivers/bus/mhi/core/main.c
@@ -430,7 +430,7 @@  irqreturn_t mhi_intvec_threaded_handler(int irq_number, void *priv)
 	struct device *dev = &mhi_cntrl->mhi_dev->dev;
 	enum mhi_state state = MHI_STATE_MAX;
 	enum mhi_pm_state pm_state = 0;
-	enum mhi_ee_type ee = 0;
+	enum mhi_ee_type ee = MHI_EE_MAX;
 
 	write_lock_irq(&mhi_cntrl->pm_lock);
 	if (!MHI_REG_ACCESS_VALID(mhi_cntrl->pm_state)) {
@@ -439,8 +439,7 @@  irqreturn_t mhi_intvec_threaded_handler(int irq_number, void *priv)
 	}
 
 	state = mhi_get_mhi_state(mhi_cntrl);
-	ee = mhi_cntrl->ee;
-	mhi_cntrl->ee = mhi_get_exec_env(mhi_cntrl);
+	ee = mhi_get_exec_env(mhi_cntrl);
 	dev_dbg(dev, "local ee:%s device ee:%s dev_state:%s\n",
 		TO_MHI_EXEC_STR(mhi_cntrl->ee), TO_MHI_EXEC_STR(ee),
 		TO_MHI_STATE_STR(state));
@@ -452,27 +451,30 @@  irqreturn_t mhi_intvec_threaded_handler(int irq_number, void *priv)
 	}
 	write_unlock_irq(&mhi_cntrl->pm_lock);
 
-	 /* If device supports RDDM don't bother processing SYS error */
-	if (mhi_cntrl->rddm_image) {
-		/* host may be performing a device power down already */
-		if (!mhi_is_active(mhi_cntrl))
-			goto exit_intvec;
+	if (pm_state != MHI_PM_SYS_ERR_DETECT || ee == mhi_cntrl->ee)
+		goto exit_intvec;
 
-		if (mhi_cntrl->ee == MHI_EE_RDDM && mhi_cntrl->ee != ee) {
+	switch (ee) {
+	case MHI_EE_RDDM:
+		/* proceed if power down is not already in progress */
+		if (mhi_cntrl->rddm_image && mhi_is_active(mhi_cntrl)) {
 			mhi_cntrl->status_cb(mhi_cntrl, MHI_CB_EE_RDDM);
+			mhi_cntrl->ee = ee;
 			wake_up_all(&mhi_cntrl->state_event);
 		}
-		goto exit_intvec;
-	}
-
-	if (pm_state == MHI_PM_SYS_ERR_DETECT) {
+		break;
+	case MHI_EE_PBL:
+	case MHI_EE_EDL:
+	case MHI_EE_PTHRU:
+		mhi_cntrl->status_cb(mhi_cntrl, MHI_CB_FATAL_ERROR);
+		mhi_cntrl->ee = ee;
 		wake_up_all(&mhi_cntrl->state_event);
-
-		/* For fatal errors, we let controller decide next step */
-		if (MHI_IN_PBL(ee))
-			mhi_cntrl->status_cb(mhi_cntrl, MHI_CB_FATAL_ERROR);
-		else
-			mhi_pm_sys_err_handler(mhi_cntrl);
+		mhi_pm_sys_err_handler(mhi_cntrl);
+		break;
+	default:
+		wake_up_all(&mhi_cntrl->state_event);
+		mhi_pm_sys_err_handler(mhi_cntrl);
+		break;
 	}
 
 exit_intvec:
diff --git a/drivers/bus/mhi/core/pm.c b/drivers/bus/mhi/core/pm.c
index c09ec13..c870fa8 100644
--- a/drivers/bus/mhi/core/pm.c
+++ b/drivers/bus/mhi/core/pm.c
@@ -377,21 +377,22 @@  static int mhi_pm_mission_mode_transition(struct mhi_controller *mhi_cntrl)
 {
 	struct mhi_event *mhi_event;
 	struct device *dev = &mhi_cntrl->mhi_dev->dev;
-	enum mhi_ee_type current_ee = mhi_cntrl->ee;
+	enum mhi_ee_type ee = MHI_EE_MAX, current_ee = mhi_cntrl->ee;
 	int i, ret;
 
 	dev_dbg(dev, "Processing Mission Mode transition\n");
 
 	write_lock_irq(&mhi_cntrl->pm_lock);
 	if (MHI_REG_ACCESS_VALID(mhi_cntrl->pm_state))
-		mhi_cntrl->ee = mhi_get_exec_env(mhi_cntrl);
+		ee = mhi_get_exec_env(mhi_cntrl);
 
-	if (!MHI_IN_MISSION_MODE(mhi_cntrl->ee)) {
+	if (!MHI_IN_MISSION_MODE(ee)) {
 		mhi_cntrl->pm_state = MHI_PM_LD_ERR_FATAL_DETECT;
 		write_unlock_irq(&mhi_cntrl->pm_lock);
 		wake_up_all(&mhi_cntrl->state_event);
 		return -EIO;
 	}
+	mhi_cntrl->ee = ee;
 	write_unlock_irq(&mhi_cntrl->pm_lock);
 
 	wake_up_all(&mhi_cntrl->state_event);