[v5,2/2] bus: mhi: core: Move to polling method to wait for MHI ready
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Message ID 1617047583-12104-3-git-send-email-bbhatt@codeaurora.org
State New, archived
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Series
  • Polling for MHI ready
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Commit Message

Bhaumik Bhatt March 29, 2021, 7:53 p.m. UTC
In certain devices, it is likely that there is no incoming MHI
interrupt for a transition to MHI READY state. One such example
is the move from Pass Through to an SBL or AMSS execution
environment. In order to facilitate faster bootup times as there
is no need to wait until timeout_ms completes, MHI host can poll
every 25 milliseconds to check if device has entered MHI READY
until a maximum timeout of twice the timeout_ms is reached.

Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org>
---
 drivers/bus/mhi/core/pm.c | 32 +++++++++++++++-----------------
 1 file changed, 15 insertions(+), 17 deletions(-)

Comments

Manivannan Sadhasivam March 31, 2021, 1:04 p.m. UTC | #1
On Mon, Mar 29, 2021 at 12:53:03PM -0700, Bhaumik Bhatt wrote:
> In certain devices, it is likely that there is no incoming MHI
> interrupt for a transition to MHI READY state. One such example
> is the move from Pass Through to an SBL or AMSS execution
> environment. In order to facilitate faster bootup times as there
> is no need to wait until timeout_ms completes, MHI host can poll
> every 25 milliseconds to check if device has entered MHI READY
> until a maximum timeout of twice the timeout_ms is reached.
> 
> Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org>
> ---
>  drivers/bus/mhi/core/pm.c | 32 +++++++++++++++-----------------
>  1 file changed, 15 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/bus/mhi/core/pm.c b/drivers/bus/mhi/core/pm.c
> index 681960c..dcc7fe0 100644
> --- a/drivers/bus/mhi/core/pm.c
> +++ b/drivers/bus/mhi/core/pm.c
> @@ -153,34 +153,32 @@ static void mhi_toggle_dev_wake(struct mhi_controller *mhi_cntrl)
>  /* Handle device ready state transition */
>  int mhi_ready_state_transition(struct mhi_controller *mhi_cntrl)
>  {
> -	void __iomem *base = mhi_cntrl->regs;
>  	struct mhi_event *mhi_event;
>  	enum mhi_pm_state cur_state;
>  	struct device *dev = &mhi_cntrl->mhi_dev->dev;
> -	u32 reset = 1, ready = 0;
> +	u32 interval_us = 25000; /* poll register field every 25 milliseconds */
>  	int ret, i;
>  
> -	/* Wait for RESET to be cleared and READY bit to be set by the device */
> -	wait_event_timeout(mhi_cntrl->state_event,
> -			   MHI_PM_IN_FATAL_STATE(mhi_cntrl->pm_state) ||
> -			   mhi_read_reg_field(mhi_cntrl, base, MHICTRL,
> -					      MHICTRL_RESET_MASK,
> -					      MHICTRL_RESET_SHIFT, &reset) ||
> -			   mhi_read_reg_field(mhi_cntrl, base, MHISTATUS,
> -					      MHISTATUS_READY_MASK,
> -					      MHISTATUS_READY_SHIFT, &ready) ||
> -			   (!reset && ready),
> -			   msecs_to_jiffies(mhi_cntrl->timeout_ms));
> -
>  	/* Check if device entered error state */
>  	if (MHI_PM_IN_FATAL_STATE(mhi_cntrl->pm_state)) {
>  		dev_err(dev, "Device link is not accessible\n");
>  		return -EIO;
>  	}
>  
> -	/* Timeout if device did not transition to ready state */
> -	if (reset || !ready) {
> -		dev_err(dev, "Device Ready timeout\n");
> +	/* Wait for RESET to be cleared and READY bit to be set by the device */
> +	ret = mhi_poll_reg_field(mhi_cntrl, mhi_cntrl->regs, MHICTRL,
> +				 MHICTRL_RESET_MASK, MHICTRL_RESET_SHIFT, 0,
> +				 interval_us);
> +	if (ret) {
> +		dev_err(dev, "Device failed to clear MHI Reset\n");
> +		return -ETIMEDOUT;

You should return the actual error code since there are couple of error
paths.

Thanks,
Mani

> +	}
> +
> +	ret = mhi_poll_reg_field(mhi_cntrl, mhi_cntrl->regs, MHISTATUS,
> +				 MHISTATUS_READY_MASK, MHISTATUS_READY_SHIFT, 1,
> +				 interval_us);
> +	if (ret) {
> +		dev_err(dev, "Device failed to enter MHI Ready\n");
>  		return -ETIMEDOUT;
>  	}
>  
> -- 
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>
Bhaumik Bhatt March 31, 2021, 5:23 p.m. UTC | #2
On 2021-03-31 06:04 AM, Manivannan Sadhasivam wrote:
> On Mon, Mar 29, 2021 at 12:53:03PM -0700, Bhaumik Bhatt wrote:
>> In certain devices, it is likely that there is no incoming MHI
>> interrupt for a transition to MHI READY state. One such example
>> is the move from Pass Through to an SBL or AMSS execution
>> environment. In order to facilitate faster bootup times as there
>> is no need to wait until timeout_ms completes, MHI host can poll
>> every 25 milliseconds to check if device has entered MHI READY
>> until a maximum timeout of twice the timeout_ms is reached.
>> 
>> Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org>
>> ---
>>  drivers/bus/mhi/core/pm.c | 32 +++++++++++++++-----------------
>>  1 file changed, 15 insertions(+), 17 deletions(-)
>> 
>> diff --git a/drivers/bus/mhi/core/pm.c b/drivers/bus/mhi/core/pm.c
>> index 681960c..dcc7fe0 100644
>> --- a/drivers/bus/mhi/core/pm.c
>> +++ b/drivers/bus/mhi/core/pm.c
>> @@ -153,34 +153,32 @@ static void mhi_toggle_dev_wake(struct 
>> mhi_controller *mhi_cntrl)
>>  /* Handle device ready state transition */
>>  int mhi_ready_state_transition(struct mhi_controller *mhi_cntrl)
>>  {
>> -	void __iomem *base = mhi_cntrl->regs;
>>  	struct mhi_event *mhi_event;
>>  	enum mhi_pm_state cur_state;
>>  	struct device *dev = &mhi_cntrl->mhi_dev->dev;
>> -	u32 reset = 1, ready = 0;
>> +	u32 interval_us = 25000; /* poll register field every 25 
>> milliseconds */
>>  	int ret, i;
>> 
>> -	/* Wait for RESET to be cleared and READY bit to be set by the 
>> device */
>> -	wait_event_timeout(mhi_cntrl->state_event,
>> -			   MHI_PM_IN_FATAL_STATE(mhi_cntrl->pm_state) ||
>> -			   mhi_read_reg_field(mhi_cntrl, base, MHICTRL,
>> -					      MHICTRL_RESET_MASK,
>> -					      MHICTRL_RESET_SHIFT, &reset) ||
>> -			   mhi_read_reg_field(mhi_cntrl, base, MHISTATUS,
>> -					      MHISTATUS_READY_MASK,
>> -					      MHISTATUS_READY_SHIFT, &ready) ||
>> -			   (!reset && ready),
>> -			   msecs_to_jiffies(mhi_cntrl->timeout_ms));
>> -
>>  	/* Check if device entered error state */
>>  	if (MHI_PM_IN_FATAL_STATE(mhi_cntrl->pm_state)) {
>>  		dev_err(dev, "Device link is not accessible\n");
>>  		return -EIO;
>>  	}
>> 
>> -	/* Timeout if device did not transition to ready state */
>> -	if (reset || !ready) {
>> -		dev_err(dev, "Device Ready timeout\n");
>> +	/* Wait for RESET to be cleared and READY bit to be set by the 
>> device */
>> +	ret = mhi_poll_reg_field(mhi_cntrl, mhi_cntrl->regs, MHICTRL,
>> +				 MHICTRL_RESET_MASK, MHICTRL_RESET_SHIFT, 0,
>> +				 interval_us);
>> +	if (ret) {
>> +		dev_err(dev, "Device failed to clear MHI Reset\n");
>> +		return -ETIMEDOUT;
> 
> You should return the actual error code since there are couple of error
> paths.
> 
> Thanks,
> Mani
> 
Sure. With the update on patch #1, this will be taken care of properly 
as we
return -ETIMEDOUT from the API.
>> +	}
>> +
>> +	ret = mhi_poll_reg_field(mhi_cntrl, mhi_cntrl->regs, MHISTATUS,
>> +				 MHISTATUS_READY_MASK, MHISTATUS_READY_SHIFT, 1,
>> +				 interval_us);
>> +	if (ret) {
>> +		dev_err(dev, "Device failed to enter MHI Ready\n");
>>  		return -ETIMEDOUT;
>>  	}
>> 
>> --
>> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora 
>> Forum,
>> a Linux Foundation Collaborative Project
>> 

Thanks,
Bhaumik
---
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/pm.c b/drivers/bus/mhi/core/pm.c
index 681960c..dcc7fe0 100644
--- a/drivers/bus/mhi/core/pm.c
+++ b/drivers/bus/mhi/core/pm.c
@@ -153,34 +153,32 @@  static void mhi_toggle_dev_wake(struct mhi_controller *mhi_cntrl)
 /* Handle device ready state transition */
 int mhi_ready_state_transition(struct mhi_controller *mhi_cntrl)
 {
-	void __iomem *base = mhi_cntrl->regs;
 	struct mhi_event *mhi_event;
 	enum mhi_pm_state cur_state;
 	struct device *dev = &mhi_cntrl->mhi_dev->dev;
-	u32 reset = 1, ready = 0;
+	u32 interval_us = 25000; /* poll register field every 25 milliseconds */
 	int ret, i;
 
-	/* Wait for RESET to be cleared and READY bit to be set by the device */
-	wait_event_timeout(mhi_cntrl->state_event,
-			   MHI_PM_IN_FATAL_STATE(mhi_cntrl->pm_state) ||
-			   mhi_read_reg_field(mhi_cntrl, base, MHICTRL,
-					      MHICTRL_RESET_MASK,
-					      MHICTRL_RESET_SHIFT, &reset) ||
-			   mhi_read_reg_field(mhi_cntrl, base, MHISTATUS,
-					      MHISTATUS_READY_MASK,
-					      MHISTATUS_READY_SHIFT, &ready) ||
-			   (!reset && ready),
-			   msecs_to_jiffies(mhi_cntrl->timeout_ms));
-
 	/* Check if device entered error state */
 	if (MHI_PM_IN_FATAL_STATE(mhi_cntrl->pm_state)) {
 		dev_err(dev, "Device link is not accessible\n");
 		return -EIO;
 	}
 
-	/* Timeout if device did not transition to ready state */
-	if (reset || !ready) {
-		dev_err(dev, "Device Ready timeout\n");
+	/* Wait for RESET to be cleared and READY bit to be set by the device */
+	ret = mhi_poll_reg_field(mhi_cntrl, mhi_cntrl->regs, MHICTRL,
+				 MHICTRL_RESET_MASK, MHICTRL_RESET_SHIFT, 0,
+				 interval_us);
+	if (ret) {
+		dev_err(dev, "Device failed to clear MHI Reset\n");
+		return -ETIMEDOUT;
+	}
+
+	ret = mhi_poll_reg_field(mhi_cntrl, mhi_cntrl->regs, MHISTATUS,
+				 MHISTATUS_READY_MASK, MHISTATUS_READY_SHIFT, 1,
+				 interval_us);
+	if (ret) {
+		dev_err(dev, "Device failed to enter MHI Ready\n");
 		return -ETIMEDOUT;
 	}