[PATCH v3] drm/msm/dp: update is_connected status base on sink count at dp_pm_resume()

[PATCH v3] drm/msm/dp: update is_connected status base on sink count at dp_pm_resume()

[Kuogee Hsieh]

Currently at dp_pm_resume() is_connected state is decided base on hpd connection
status only. This will put is_connected in wrongly "true" state at the scenario
that dongle attached to DUT but without hmdi cable connecting to it. Fix this
problem by adding read sink count from dongle and decided is_connected state base
on both sink count and hpd connection status.

Changes in v2:
-- remove dp_get_sink_count() cand call drm_dp_read_sink_count()

Changes in v3:
-- delete status local variable from dp_pm_resume()

Fixes: d9aa6571b28ba ("drm/msm/dp: check sink_count before update is_connected status")
Signed-off-by: Kuogee Hsieh <khsieh@codeaurora.org>
---
 drivers/gpu/drm/msm/dp/dp_display.c | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
index 78c5301..0f39256 100644
--- a/drivers/gpu/drm/msm/dp/dp_display.c
+++ b/drivers/gpu/drm/msm/dp/dp_display.c
@@ -1313,7 +1313,7 @@ static int dp_pm_resume(struct device *dev)
 	struct platform_device *pdev = to_platform_device(dev);
 	struct msm_dp *dp_display = platform_get_drvdata(pdev);
 	struct dp_display_private *dp;
-	u32 status;
+	int sink_count = 0;
 
 	dp = container_of(dp_display, struct dp_display_private, dp_display);
 
@@ -1327,14 +1327,26 @@ static int dp_pm_resume(struct device *dev)
 
 	dp_catalog_ctrl_hpd_config(dp->catalog);
 
-	status = dp_catalog_link_is_connected(dp->catalog);
+	/*
+	 * set sink to normal operation mode -- D0
+	 * before dpcd read
+	 */
+	dp_link_psm_config(dp->link, &dp->panel->link_info, false);
+
+	/* if sink conencted, do dpcd read sink count */
+	if (dp_catalog_link_is_connected(dp->catalog)) {
+		sink_count = drm_dp_read_sink_count(dp->aux);
+		if (sink_count < 0)
+			sink_count = 0;
+	}
 
+	dp->link->sink_count = sink_count;
 	/*
 	 * can not declared display is connected unless
 	 * HDMI cable is plugged in and sink_count of
 	 * dongle become 1
 	 */
-	if (status && dp->link->sink_count)
+	if (dp->link->sink_count)
 		dp->dp_display.is_connected = true;
 	else
 		dp->dp_display.is_connected = false;
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

Re: [PATCH v3] drm/msm/dp: update is_connected status base on sink count at dp_pm_resume()

[Stephen Boyd]

Quoting Kuogee Hsieh (2021-08-03 09:25:13)
> Currently at dp_pm_resume() is_connected state is decided base on hpd connection
> status only. This will put is_connected in wrongly "true" state at the scenario
> that dongle attached to DUT but without hmdi cable connecting to it. Fix this
> problem by adding read sink count from dongle and decided is_connected state base
> on both sink count and hpd connection status.
>
> Changes in v2:
> -- remove dp_get_sink_count() cand call drm_dp_read_sink_count()
>
> Changes in v3:
> -- delete status local variable from dp_pm_resume()
>
> Fixes: d9aa6571b28ba ("drm/msm/dp: check sink_count before update is_connected status")
> Signed-off-by: Kuogee Hsieh <khsieh@codeaurora.org>
> ---
>  drivers/gpu/drm/msm/dp/dp_display.c | 18 +++++++++++++++---
>  1 file changed, 15 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
> index 78c5301..0f39256 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.c
> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> @@ -1313,7 +1313,7 @@ static int dp_pm_resume(struct device *dev)
>         struct platform_device *pdev = to_platform_device(dev);
>         struct msm_dp *dp_display = platform_get_drvdata(pdev);
>         struct dp_display_private *dp;
> -       u32 status;
> +       int sink_count = 0;
>
>         dp = container_of(dp_display, struct dp_display_private, dp_display);
>
> @@ -1327,14 +1327,26 @@ static int dp_pm_resume(struct device *dev)
>
>         dp_catalog_ctrl_hpd_config(dp->catalog);
>
> -       status = dp_catalog_link_is_connected(dp->catalog);
> +       /*
> +        * set sink to normal operation mode -- D0
> +        * before dpcd read
> +        */
> +       dp_link_psm_config(dp->link, &dp->panel->link_info, false);
> +
> +       /* if sink conencted, do dpcd read sink count */

s/conencted/connected/

This also just says what the code is doing. Why do we only read the sink
count if the link is connected? Can we read the sink count even if the
link isn't connected and then consider sink count as 0 if trying to read
fails?

> +       if (dp_catalog_link_is_connected(dp->catalog)) {
> +               sink_count = drm_dp_read_sink_count(dp->aux);
> +               if (sink_count < 0)
> +                       sink_count = 0;
> +       }
>
> +       dp->link->sink_count = sink_count;
>         /*
>          * can not declared display is connected unless
>          * HDMI cable is plugged in and sink_count of
>          * dongle become 1
>          */
> -       if (status && dp->link->sink_count)
> +       if (dp->link->sink_count)
>                 dp->dp_display.is_connected = true;
>         else
>                 dp->dp_display.is_connected = false;

Re: [PATCH v3] drm/msm/dp: update is_connected status base on sink count at dp_pm_resume()

[khsieh]

On 2021-08-03 12:05, Stephen Boyd wrote:
> Quoting Kuogee Hsieh (2021-08-03 09:25:13)
>> Currently at dp_pm_resume() is_connected state is decided base on hpd 
>> connection
>> status only. This will put is_connected in wrongly "true" state at the 
>> scenario
>> that dongle attached to DUT but without hmdi cable connecting to it. 
>> Fix this
>> problem by adding read sink count from dongle and decided is_connected 
>> state base
>> on both sink count and hpd connection status.
>> 
>> Changes in v2:
>> -- remove dp_get_sink_count() cand call drm_dp_read_sink_count()
>> 
>> Changes in v3:
>> -- delete status local variable from dp_pm_resume()
>> 
>> Fixes: d9aa6571b28ba ("drm/msm/dp: check sink_count before update 
>> is_connected status")
>> Signed-off-by: Kuogee Hsieh <khsieh@codeaurora.org>
>> ---
>>  drivers/gpu/drm/msm/dp/dp_display.c | 18 +++++++++++++++---
>>  1 file changed, 15 insertions(+), 3 deletions(-)
>> 
>> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c 
>> b/drivers/gpu/drm/msm/dp/dp_display.c
>> index 78c5301..0f39256 100644
>> --- a/drivers/gpu/drm/msm/dp/dp_display.c
>> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
>> @@ -1313,7 +1313,7 @@ static int dp_pm_resume(struct device *dev)
>>         struct platform_device *pdev = to_platform_device(dev);
>>         struct msm_dp *dp_display = platform_get_drvdata(pdev);
>>         struct dp_display_private *dp;
>> -       u32 status;
>> +       int sink_count = 0;
>> 
>>         dp = container_of(dp_display, struct dp_display_private, 
>> dp_display);
>> 
>> @@ -1327,14 +1327,26 @@ static int dp_pm_resume(struct device *dev)
>> 
>>         dp_catalog_ctrl_hpd_config(dp->catalog);
>> 
>> -       status = dp_catalog_link_is_connected(dp->catalog);
>> +       /*
>> +        * set sink to normal operation mode -- D0
>> +        * before dpcd read
>> +        */
>> +       dp_link_psm_config(dp->link, &dp->panel->link_info, false);
>> +
>> +       /* if sink conencted, do dpcd read sink count */
> 
> s/conencted/connected/
> 
> This also just says what the code is doing. Why do we only read the 
> sink
> count if the link is connected? Can we read the sink count even if the
> link isn't connected and then consider sink count as 0 if trying to 
> read
> fails?
> 
yes, we can do that.
But it will suffer aux time out and retry.
i think it is better to avoid this overhead by check connection first.

>> +       if (dp_catalog_link_is_connected(dp->catalog)) {
>> +               sink_count = drm_dp_read_sink_count(dp->aux);
>> +               if (sink_count < 0)
>> +                       sink_count = 0;
>> +       }
>> 
>> +       dp->link->sink_count = sink_count;
>>         /*
>>          * can not declared display is connected unless
>>          * HDMI cable is plugged in and sink_count of
>>          * dongle become 1
>>          */
>> -       if (status && dp->link->sink_count)
>> +       if (dp->link->sink_count)
>>                 dp->dp_display.is_connected = true;
>>         else
>>                 dp->dp_display.is_connected = false;

Re: [PATCH v3] drm/msm/dp: update is_connected status base on sink count at dp_pm_resume()

[Stephen Boyd]

Quoting khsieh@codeaurora.org (2021-08-04 08:48:04)
> On 2021-08-03 12:05, Stephen Boyd wrote:
> > Quoting Kuogee Hsieh (2021-08-03 09:25:13)
> >> @@ -1327,14 +1327,26 @@ static int dp_pm_resume(struct device *dev)
> >>
> >>         dp_catalog_ctrl_hpd_config(dp->catalog);
> >>
> >> -       status = dp_catalog_link_is_connected(dp->catalog);
> >> +       /*
> >> +        * set sink to normal operation mode -- D0
> >> +        * before dpcd read
> >> +        */
> >> +       dp_link_psm_config(dp->link, &dp->panel->link_info, false);
> >> +
> >> +       /* if sink conencted, do dpcd read sink count */
> >
> > s/conencted/connected/
> >
> > This also just says what the code is doing. Why do we only read the
> > sink
> > count if the link is connected? Can we read the sink count even if the
> > link isn't connected and then consider sink count as 0 if trying to
> > read
> > fails?
> >
> yes, we can do that.
> But it will suffer aux time out and retry.
> i think it is better to avoid this overhead by check connection first.
>

Hmm ok. Maybe something is wrong with the aux channel where it doesn't
avoid the timeout if the connection is obviously not established yet.