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[PATCH v5 3/3] drm/msm/dp: retry 3 times if set sink to D0 poweer state failed

Kuogee Hsieh posted 3 patches 3 years, 6 months ago
[PATCH v5 3/3] drm/msm/dp: retry 3 times if set sink to D0 poweer state failed
Posted by Kuogee Hsieh 3 years, 6 months ago 
Bring sink out of D3 (power down) mode into D0 (normal operation) mode
by setting DP_SET_POWER_D0 bit to DP_SET_POWER dpcd register. This
patch will retry 3 times if written to DP_SET_POWER register failed.

Changes in v5:
-- split into two patches

Signed-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
---
 drivers/gpu/drm/msm/dp/dp_link.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/msm/dp/dp_link.c b/drivers/gpu/drm/msm/dp/dp_link.c
index 9d5381d..4360728 100644
--- a/drivers/gpu/drm/msm/dp/dp_link.c
+++ b/drivers/gpu/drm/msm/dp/dp_link.c
@@ -50,6 +50,7 @@ static int dp_aux_link_power_up(struct drm_dp_aux *aux,
 {
 	u8 value;
 	ssize_t len;
+	int i;
 
 	if (link->revision < 0x11)
 		return 0;
@@ -61,11 +62,13 @@ static int dp_aux_link_power_up(struct drm_dp_aux *aux,
 	value &= ~DP_SET_POWER_MASK;
 	value |= DP_SET_POWER_D0;
 
-	len = drm_dp_dpcd_writeb(aux, DP_SET_POWER, value);
-	if (len < 0)
-		return len;
-
-	usleep_range(1000, 2000);
+	/* retry for 1ms to give the sink time to wake up */
+	for (i = 0; i < 3; i++) {
+		len = drm_dp_dpcd_writeb(aux, DP_SET_POWER, value);
+		usleep_range(1000, 2000);
+		if (len == 1)
+			break;
+	}
 
 	return 0;
 }
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
Re: [PATCH v5 3/3] drm/msm/dp: retry 3 times if set sink to D0 poweer state failed
Posted by Dmitry Baryshkov 3 years, 6 months ago 
On 12/09/2022 19:23, Kuogee Hsieh wrote:
> Bring sink out of D3 (power down) mode into D0 (normal operation) mode
> by setting DP_SET_POWER_D0 bit to DP_SET_POWER dpcd register. This
> patch will retry 3 times if written to DP_SET_POWER register failed.

Could you please elaborate this change? Can the sink succeed in reading 
the DP_SET_POWER, but fail writing DP_SET_POWER?

> 
> Changes in v5:
> -- split into two patches
> 
> Signed-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
> ---
>   drivers/gpu/drm/msm/dp/dp_link.c | 13 ++++++++-----
>   1 file changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/dp/dp_link.c b/drivers/gpu/drm/msm/dp/dp_link.c
> index 9d5381d..4360728 100644
> --- a/drivers/gpu/drm/msm/dp/dp_link.c
> +++ b/drivers/gpu/drm/msm/dp/dp_link.c
> @@ -50,6 +50,7 @@ static int dp_aux_link_power_up(struct drm_dp_aux *aux,
>   {
>   	u8 value;
>   	ssize_t len;
> +	int i;
>   
>   	if (link->revision < 0x11)
>   		return 0;
> @@ -61,11 +62,13 @@ static int dp_aux_link_power_up(struct drm_dp_aux *aux,
>   	value &= ~DP_SET_POWER_MASK;
>   	value |= DP_SET_POWER_D0;
>   
> -	len = drm_dp_dpcd_writeb(aux, DP_SET_POWER, value);
> -	if (len < 0)
> -		return len;
> -
> -	usleep_range(1000, 2000);
> +	/* retry for 1ms to give the sink time to wake up */
> +	for (i = 0; i < 3; i++) {
> +		len = drm_dp_dpcd_writeb(aux, DP_SET_POWER, value);
> +		usleep_range(1000, 2000);
> +		if (len == 1)
> +			break;
> +	}
>   
>   	return 0;
>   }

-- 
With best wishes
Dmitry
Re: [PATCH v5 3/3] drm/msm/dp: retry 3 times if set sink to D0 poweer state failed
Posted by Kuogee Hsieh 3 years, 6 months ago 
On 9/12/2022 11:37 AM, Dmitry Baryshkov wrote:
> On 12/09/2022 19:23, Kuogee Hsieh wrote:
>> Bring sink out of D3 (power down) mode into D0 (normal operation) mode
>> by setting DP_SET_POWER_D0 bit to DP_SET_POWER dpcd register. This
>> patch will retry 3 times if written to DP_SET_POWER register failed.
>
> Could you please elaborate this change? Can the sink succeed in 
> reading the DP_SET_POWER, but fail writing DP_SET_POWER?

yes, there is possible since it is not only set local sink device but 
also all downstream sink devices to D0 state.

>
>>
>> Changes in v5:
>> -- split into two patches
>>
>> Signed-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
>> ---
>>   drivers/gpu/drm/msm/dp/dp_link.c | 13 ++++++++-----
>>   1 file changed, 8 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/msm/dp/dp_link.c 
>> b/drivers/gpu/drm/msm/dp/dp_link.c
>> index 9d5381d..4360728 100644
>> --- a/drivers/gpu/drm/msm/dp/dp_link.c
>> +++ b/drivers/gpu/drm/msm/dp/dp_link.c
>> @@ -50,6 +50,7 @@ static int dp_aux_link_power_up(struct drm_dp_aux 
>> *aux,
>>   {
>>       u8 value;
>>       ssize_t len;
>> +    int i;
>>         if (link->revision < 0x11)
>>           return 0;
>> @@ -61,11 +62,13 @@ static int dp_aux_link_power_up(struct drm_dp_aux 
>> *aux,
>>       value &= ~DP_SET_POWER_MASK;
>>       value |= DP_SET_POWER_D0;
>>   -    len = drm_dp_dpcd_writeb(aux, DP_SET_POWER, value);
>> -    if (len < 0)
>> -        return len;
>> -
>> -    usleep_range(1000, 2000);
>> +    /* retry for 1ms to give the sink time to wake up */
>> +    for (i = 0; i < 3; i++) {
>> +        len = drm_dp_dpcd_writeb(aux, DP_SET_POWER, value);
>> +        usleep_range(1000, 2000);
>> +        if (len == 1)
>> +            break;
>> +    }
>>         return 0;
>>   }
>
Re: [PATCH v5 3/3] drm/msm/dp: retry 3 times if set sink to D0 poweer state failed
Posted by Dmitry Baryshkov 3 years, 5 months ago 
On 12/09/2022 22:26, Kuogee Hsieh wrote:
> 
> On 9/12/2022 11:37 AM, Dmitry Baryshkov wrote:
>> On 12/09/2022 19:23, Kuogee Hsieh wrote:
>>> Bring sink out of D3 (power down) mode into D0 (normal operation) mode
>>> by setting DP_SET_POWER_D0 bit to DP_SET_POWER dpcd register. This
>>> patch will retry 3 times if written to DP_SET_POWER register failed.
>>
>> Could you please elaborate this change? Can the sink succeed in 
>> reading the DP_SET_POWER, but fail writing DP_SET_POWER?
> 
> yes, there is possible since it is not only set local sink device but 
> also all downstream sink devices to D0 state.

Ack. Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

> 
>>
>>>
>>> Changes in v5:
>>> -- split into two patches
>>>
>>> Signed-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
>>> ---
>>>   drivers/gpu/drm/msm/dp/dp_link.c | 13 ++++++++-----
>>>   1 file changed, 8 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/msm/dp/dp_link.c 
>>> b/drivers/gpu/drm/msm/dp/dp_link.c
>>> index 9d5381d..4360728 100644
>>> --- a/drivers/gpu/drm/msm/dp/dp_link.c
>>> +++ b/drivers/gpu/drm/msm/dp/dp_link.c
>>> @@ -50,6 +50,7 @@ static int dp_aux_link_power_up(struct drm_dp_aux 
>>> *aux,
>>>   {
>>>       u8 value;
>>>       ssize_t len;
>>> +    int i;
>>>         if (link->revision < 0x11)
>>>           return 0;
>>> @@ -61,11 +62,13 @@ static int dp_aux_link_power_up(struct drm_dp_aux 
>>> *aux,
>>>       value &= ~DP_SET_POWER_MASK;
>>>       value |= DP_SET_POWER_D0;
>>>   -    len = drm_dp_dpcd_writeb(aux, DP_SET_POWER, value);
>>> -    if (len < 0)
>>> -        return len;
>>> -
>>> -    usleep_range(1000, 2000);
>>> +    /* retry for 1ms to give the sink time to wake up */
>>> +    for (i = 0; i < 3; i++) {
>>> +        len = drm_dp_dpcd_writeb(aux, DP_SET_POWER, value);
>>> +        usleep_range(1000, 2000);
>>> +        if (len == 1)
>>> +            break;
>>> +    }
>>>         return 0;
>>>   }
>>

-- 
With best wishes
Dmitry

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