Re: [Intel-gfx] [PATCH 4/4] drm/i915: force full detect on sink count change

[Sivakumar Thulasimani]

On 9/2/2015 2:43 PM, Daniel Vetter wrote:

On Thu, Aug 27, 2015 at 02:18:32PM +0530, Sivakumar Thulasimani wrote:

From: "Thulasimani,Sivakumar" 

This patch checks for changes in sink count between short pulse
hpds and forces full detect when there is a change.

This will allow both detection of hotplug and unplug of panels
through dongles that give only short pulse for such events.

v2: changed variable type from u8 to bool (Jani)
 return immediately if perform_full_detect is set(Siva)

Signed-off-by: Sivakumar Thulasimani 

That's still incomplete since in the hotplug work function we check
whether ->detect status has changed. If that doesn't happen (e.g. sink
count changes from 1->2 or whatever) then we'll fail to generate the
required uevent.

I suspect the only clean way to fix this is to merge all the dp hpd
handling together into one place and stop using ->detect for some parts of
it. Then we would have one place only that decides whether anything
changed, and whether we need to send anything to userspace or not.
-Daniel

i doubt sink count change from 1->2 is valid.
1)  we support only edp and SST displays in intel_dp_detect.
we should handle all mst related code in intel_dp_hpd_pulse.
2) check_link_status is called from withing !mst check so i dont see it 
change from 1 to 2.
3) even if it changes from 1 to 2, for the given port without mst there 
is no way to

switch between first sink to second one outside mst logic.

correct me if i am wrong, the only reason to call intel_dp_detect is to 
see if
"one display is connected or disconnected" which i feel is fine with 
current code.


But i do agree that we need to clean up intel_dp_hpd_pulse since it does 
a lot of things
then repeats those same operations in intel_dp_detect. for example we 
read dpcd 0-14,
link status and probe oui only to repeat the same steps in the 
intel_dp_detect. considering

that our dpcd read has 1ms delay this can add up pretty quick.

if the intention of intel_dp_hpd_pulse is to handle mst displays, that 
should be checked first
and continue only if display is mst otherwise we should just jump to 
intel_dp_detect.

---
  drivers/gpu/drm/i915/intel_dp.c |   27 ++-
  1 file changed, 22 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 834f513..279e52c 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -4370,26 +4370,39 @@ go_again:
   *  4. Check link status on receipt of hot-plug interrupt
   */
  static void
-intel_dp_check_link_status(struct intel_dp *intel_dp)
+intel_dp_check_link_status(struct intel_dp *intel_dp, bool 
*perform_full_detect)
  {
struct drm_device *dev = intel_dp_to_dev(intel_dp);
struct intel_encoder *intel_encoder = _to_dig_port(intel_dp)->base;
struct intel_crtc *crtc =
to_intel_crtc(dp_to_dig_port(intel_dp)->base.base.crtc);
u8 sink_irq_vector;
+   u8 old_sink_count = intel_dp->sink_count;
+   bool ret;
u8 link_status[DP_LINK_STATUS_SIZE];
  
  	WARN_ON(!drm_modeset_is_locked(>mode_config.connection_mutex));
  
+	*perform_full_detect = false;

+
/* Try to read receiver status if the link appears to be up */
if (!intel_dp_get_link_status(intel_dp, link_status)) {
return;
}
  
-	/* Now read the DPCD to see if it's actually running */

-   if (!intel_dp_get_dpcd(intel_dp)) {
+   /* Now read the DPCD to see if it's actually running
+* Don't return immediately if dpcd read failed,
+* if sink count was 1 and dpcd read failed we need
+* to do full detection
+*/
+   ret = intel_dp_get_dpcd(intel_dp);
+
+   if (old_sink_count != intel_dp->sink_count)
+   *perform_full_detect = true;
+
+   /* No need to proceed if we are going to do full detect */
+   if (!ret || *perform_full_detect)
return;
-   }
  
  	if (!intel_encoder->base.crtc)

return;
@@ -5031,13 +5044,17 @@ intel_dp_hpd_pulse(struct intel_digital_port 
*intel_dig_port, bool long_hpd)
}
  
  		if (!intel_dp->is_mst) {

+   bool full_detect;
/*
 * we'll check the link status via the normal hot plug 
path later -
 * but for short hpds we should check it now
 */
drm_modeset_lock(>mode_config.connection_mutex, 
NULL);
-   intel_dp_check_link_status(intel_dp);
+   intel_dp_check_link_status(intel_dp, _detect);
drm_modeset_unlock(>mode_config.connection_mutex);
+
+   if (full_detect)
+   goto put_power;
}
}
  
--

1.7.9.5

___

Re: [Intel-gfx] [PATCH 4/4] drm/i915: force full detect on sink count change

[Daniel Vetter]

On Thu, Aug 27, 2015 at 02:18:32PM +0530, Sivakumar Thulasimani wrote:
> From: "Thulasimani,Sivakumar" 
> 
> This patch checks for changes in sink count between short pulse
> hpds and forces full detect when there is a change.
> 
> This will allow both detection of hotplug and unplug of panels
> through dongles that give only short pulse for such events.
> 
> v2: changed variable type from u8 to bool (Jani)
> return immediately if perform_full_detect is set(Siva)
> 
> Signed-off-by: Sivakumar Thulasimani 

That's still incomplete since in the hotplug work function we check
whether ->detect status has changed. If that doesn't happen (e.g. sink
count changes from 1->2 or whatever) then we'll fail to generate the
required uevent.

I suspect the only clean way to fix this is to merge all the dp hpd
handling together into one place and stop using ->detect for some parts of
it. Then we would have one place only that decides whether anything
changed, and whether we need to send anything to userspace or not.
-Daniel

> ---
>  drivers/gpu/drm/i915/intel_dp.c |   27 ++-
>  1 file changed, 22 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 834f513..279e52c 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -4370,26 +4370,39 @@ go_again:
>   *  4. Check link status on receipt of hot-plug interrupt
>   */
>  static void
> -intel_dp_check_link_status(struct intel_dp *intel_dp)
> +intel_dp_check_link_status(struct intel_dp *intel_dp, bool 
> *perform_full_detect)
>  {
>   struct drm_device *dev = intel_dp_to_dev(intel_dp);
>   struct intel_encoder *intel_encoder = _to_dig_port(intel_dp)->base;
>   struct intel_crtc *crtc =
>   to_intel_crtc(dp_to_dig_port(intel_dp)->base.base.crtc);
>   u8 sink_irq_vector;
> + u8 old_sink_count = intel_dp->sink_count;
> + bool ret;
>   u8 link_status[DP_LINK_STATUS_SIZE];
>  
>   WARN_ON(!drm_modeset_is_locked(>mode_config.connection_mutex));
>  
> + *perform_full_detect = false;
> +
>   /* Try to read receiver status if the link appears to be up */
>   if (!intel_dp_get_link_status(intel_dp, link_status)) {
>   return;
>   }
>  
> - /* Now read the DPCD to see if it's actually running */
> - if (!intel_dp_get_dpcd(intel_dp)) {
> + /* Now read the DPCD to see if it's actually running
> +  * Don't return immediately if dpcd read failed,
> +  * if sink count was 1 and dpcd read failed we need
> +  * to do full detection
> +  */
> + ret = intel_dp_get_dpcd(intel_dp);
> +
> + if (old_sink_count != intel_dp->sink_count)
> + *perform_full_detect = true;
> +
> + /* No need to proceed if we are going to do full detect */
> + if (!ret || *perform_full_detect)
>   return;
> - }
>  
>   if (!intel_encoder->base.crtc)
>   return;
> @@ -5031,13 +5044,17 @@ intel_dp_hpd_pulse(struct intel_digital_port 
> *intel_dig_port, bool long_hpd)
>   }
>  
>   if (!intel_dp->is_mst) {
> + bool full_detect;
>   /*
>* we'll check the link status via the normal hot plug 
> path later -
>* but for short hpds we should check it now
>*/
>   drm_modeset_lock(>mode_config.connection_mutex, 
> NULL);
> - intel_dp_check_link_status(intel_dp);
> + intel_dp_check_link_status(intel_dp, _detect);
>   drm_modeset_unlock(>mode_config.connection_mutex);
> +
> + if (full_detect)
> + goto put_power;
>   }
>   }
>  
> -- 
> 1.7.9.5
> 
> ___
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> Intel-gfx@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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Re: [Intel-gfx] [PATCH 4/4] drm/i915: force full detect on sink count change

[Jani Nikula]

On Thu, 27 Aug 2015, Sivakumar Thulasimani  
wrote:
> From: "Thulasimani,Sivakumar" 
>
> This patch checks for changes in sink count between short pulse
> hpds and forces full detect when there is a change.
>
> This will allow both detection of hotplug and unplug of panels
> through dongles that give only short pulse for such events.
>
> v2: changed variable type from u8 to bool (Jani)
> return immediately if perform_full_detect is set(Siva)

The general idea LGTM, however see below.

>
> Signed-off-by: Sivakumar Thulasimani 
> ---
>  drivers/gpu/drm/i915/intel_dp.c |   27 ++-
>  1 file changed, 22 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 834f513..279e52c 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -4370,26 +4370,39 @@ go_again:
>   *  4. Check link status on receipt of hot-plug interrupt
>   */
>  static void
> -intel_dp_check_link_status(struct intel_dp *intel_dp)
> +intel_dp_check_link_status(struct intel_dp *intel_dp, bool 
> *perform_full_detect)
>  {
>   struct drm_device *dev = intel_dp_to_dev(intel_dp);
>   struct intel_encoder *intel_encoder = _to_dig_port(intel_dp)->base;
>   struct intel_crtc *crtc =
>   to_intel_crtc(dp_to_dig_port(intel_dp)->base.base.crtc);
>   u8 sink_irq_vector;
> + u8 old_sink_count = intel_dp->sink_count;
> + bool ret;
>   u8 link_status[DP_LINK_STATUS_SIZE];
>  
>   WARN_ON(!drm_modeset_is_locked(>mode_config.connection_mutex));
>  
> + *perform_full_detect = false;
> +
>   /* Try to read receiver status if the link appears to be up */
>   if (!intel_dp_get_link_status(intel_dp, link_status)) {
>   return;
>   }
>  
> - /* Now read the DPCD to see if it's actually running */
> - if (!intel_dp_get_dpcd(intel_dp)) {
> + /* Now read the DPCD to see if it's actually running
> +  * Don't return immediately if dpcd read failed,
> +  * if sink count was 1 and dpcd read failed we need
> +  * to do full detection
> +  */
> + ret = intel_dp_get_dpcd(intel_dp);
> +
> + if (old_sink_count != intel_dp->sink_count)
> + *perform_full_detect = true;

The point I was trying to make earlier is that how can you trust
intel_dp->sink_count if intel_dp_get_dpcd failed? You don't know where
it failed, and ->sink_count may or may not have changed. Maybe it has
changed for real but you didn't have a chance to read it just yet.

> +
> + /* No need to proceed if we are going to do full detect */
> + if (!ret || *perform_full_detect)
>   return;
> - }

So if you're returning because of !ret, *perform_full_detect may be true
or false, you don't know. I'd like the code to be explicit about what
you want the caller to do when intel_dp_get_dpcd returns false, full
detect or not.

BR,
Jani.

>  
>   if (!intel_encoder->base.crtc)
>   return;
> @@ -5031,13 +5044,17 @@ intel_dp_hpd_pulse(struct intel_digital_port 
> *intel_dig_port, bool long_hpd)
>   }
>  
>   if (!intel_dp->is_mst) {
> + bool full_detect;
>   /*
>* we'll check the link status via the normal hot plug 
> path later -
>* but for short hpds we should check it now
>*/
>   drm_modeset_lock(>mode_config.connection_mutex, 
> NULL);
> - intel_dp_check_link_status(intel_dp);
> + intel_dp_check_link_status(intel_dp, _detect);
>   drm_modeset_unlock(>mode_config.connection_mutex);
> +
> + if (full_detect)
> + goto put_power;
>   }
>   }
>  
> -- 
> 1.7.9.5
>

-- 
Jani Nikula, Intel Open Source Technology Center
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Re: [Intel-gfx] [PATCH 4/4] drm/i915: force full detect on sink count change

[Sivakumar Thulasimani]

On 9/1/2015 4:12 PM, Jani Nikula wrote:

On Thu, 27 Aug 2015, Sivakumar Thulasimani  
wrote:

From: "Thulasimani,Sivakumar" 

This patch checks for changes in sink count between short pulse
hpds and forces full detect when there is a change.

This will allow both detection of hotplug and unplug of panels
through dongles that give only short pulse for such events.

v2: changed variable type from u8 to bool (Jani)
 return immediately if perform_full_detect is set(Siva)

The general idea LGTM, however see below.


Signed-off-by: Sivakumar Thulasimani 
---
  drivers/gpu/drm/i915/intel_dp.c |   27 ++-
  1 file changed, 22 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 834f513..279e52c 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -4370,26 +4370,39 @@ go_again:
   *  4. Check link status on receipt of hot-plug interrupt
   */
  static void
-intel_dp_check_link_status(struct intel_dp *intel_dp)
+intel_dp_check_link_status(struct intel_dp *intel_dp, bool 
*perform_full_detect)
  {
struct drm_device *dev = intel_dp_to_dev(intel_dp);
struct intel_encoder *intel_encoder = _to_dig_port(intel_dp)->base;
struct intel_crtc *crtc =
to_intel_crtc(dp_to_dig_port(intel_dp)->base.base.crtc);
u8 sink_irq_vector;
+   u8 old_sink_count = intel_dp->sink_count;
+   bool ret;
u8 link_status[DP_LINK_STATUS_SIZE];
  
  	WARN_ON(!drm_modeset_is_locked(>mode_config.connection_mutex));
  
+	*perform_full_detect = false;

+
/* Try to read receiver status if the link appears to be up */
if (!intel_dp_get_link_status(intel_dp, link_status)) {
return;
}
  
-	/* Now read the DPCD to see if it's actually running */

-   if (!intel_dp_get_dpcd(intel_dp)) {
+   /* Now read the DPCD to see if it's actually running
+* Don't return immediately if dpcd read failed,
+* if sink count was 1 and dpcd read failed we need
+* to do full detection
+*/
+   ret = intel_dp_get_dpcd(intel_dp);
+
+   if (old_sink_count != intel_dp->sink_count)
+   *perform_full_detect = true;

The point I was trying to make earlier is that how can you trust
intel_dp->sink_count if intel_dp_get_dpcd failed? You don't know where
it failed, and ->sink_count may or may not have changed. Maybe it has
changed for real but you didn't have a chance to read it just yet.


+
+   /* No need to proceed if we are going to do full detect */
+   if (!ret || *perform_full_detect)
return;
-   }

So if you're returning because of !ret, *perform_full_detect may be true
or false, you don't know. I'd like the code to be explicit about what
you want the caller to do when intel_dp_get_dpcd returns false, full
detect or not.

BR,
Jani.
the idea i had in mind was if intel_dp_get_dpcd failed we should do a 
full detect.


my assumption here was that sink_count would be zero so it would take care
of this, but now that it seems to be a wrong assumption how about the 
following code ?

this makes it explicit that if dpcd read failed we will do full detect.

+   if ((old_sink_count != intel_dp->sink_count) || !ret)
+   *perform_full_detect = true;

+
+   /* No need to proceed if we are going to do full detect */
+   if (*perform_full_detect)
return;



  
  	if (!intel_encoder->base.crtc)

return;
@@ -5031,13 +5044,17 @@ intel_dp_hpd_pulse(struct intel_digital_port 
*intel_dig_port, bool long_hpd)
}
  
  		if (!intel_dp->is_mst) {

+   bool full_detect;
/*
 * we'll check the link status via the normal hot plug 
path later -
 * but for short hpds we should check it now
 */
drm_modeset_lock(>mode_config.connection_mutex, 
NULL);
-   intel_dp_check_link_status(intel_dp);
+   intel_dp_check_link_status(intel_dp, _detect);
drm_modeset_unlock(>mode_config.connection_mutex);
+
+   if (full_detect)
+   goto put_power;
}
}
  
--

1.7.9.5



--
regards,
Sivakumar

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Re: [Intel-gfx] [PATCH 4/4] drm/i915: force full detect on sink count change

[Jani Nikula]

On Tue, 01 Sep 2015, Sivakumar Thulasimani  
wrote:
> On 9/1/2015 4:12 PM, Jani Nikula wrote:
>> On Thu, 27 Aug 2015, Sivakumar Thulasimani  
>> wrote:
>>> From: "Thulasimani,Sivakumar" 
>>>
>>> This patch checks for changes in sink count between short pulse
>>> hpds and forces full detect when there is a change.
>>>
>>> This will allow both detection of hotplug and unplug of panels
>>> through dongles that give only short pulse for such events.
>>>
>>> v2: changed variable type from u8 to bool (Jani)
>>>  return immediately if perform_full_detect is set(Siva)
>> The general idea LGTM, however see below.
>>
>>> Signed-off-by: Sivakumar Thulasimani 
>>> ---
>>>   drivers/gpu/drm/i915/intel_dp.c |   27 ++-
>>>   1 file changed, 22 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/i915/intel_dp.c 
>>> b/drivers/gpu/drm/i915/intel_dp.c
>>> index 834f513..279e52c 100644
>>> --- a/drivers/gpu/drm/i915/intel_dp.c
>>> +++ b/drivers/gpu/drm/i915/intel_dp.c
>>> @@ -4370,26 +4370,39 @@ go_again:
>>>*  4. Check link status on receipt of hot-plug interrupt
>>>*/
>>>   static void
>>> -intel_dp_check_link_status(struct intel_dp *intel_dp)
>>> +intel_dp_check_link_status(struct intel_dp *intel_dp, bool 
>>> *perform_full_detect)
>>>   {
>>> struct drm_device *dev = intel_dp_to_dev(intel_dp);
>>> struct intel_encoder *intel_encoder = _to_dig_port(intel_dp)->base;
>>> struct intel_crtc *crtc =
>>> to_intel_crtc(dp_to_dig_port(intel_dp)->base.base.crtc);
>>> u8 sink_irq_vector;
>>> +   u8 old_sink_count = intel_dp->sink_count;
>>> +   bool ret;
>>> u8 link_status[DP_LINK_STATUS_SIZE];
>>>   
>>> WARN_ON(!drm_modeset_is_locked(>mode_config.connection_mutex));
>>>   
>>> +   *perform_full_detect = false;
>>> +
>>> /* Try to read receiver status if the link appears to be up */
>>> if (!intel_dp_get_link_status(intel_dp, link_status)) {
>>> return;
>>> }
>>>   
>>> -   /* Now read the DPCD to see if it's actually running */
>>> -   if (!intel_dp_get_dpcd(intel_dp)) {
>>> +   /* Now read the DPCD to see if it's actually running
>>> +* Don't return immediately if dpcd read failed,
>>> +* if sink count was 1 and dpcd read failed we need
>>> +* to do full detection
>>> +*/
>>> +   ret = intel_dp_get_dpcd(intel_dp);
>>> +
>>> +   if (old_sink_count != intel_dp->sink_count)
>>> +   *perform_full_detect = true;
>> The point I was trying to make earlier is that how can you trust
>> intel_dp->sink_count if intel_dp_get_dpcd failed? You don't know where
>> it failed, and ->sink_count may or may not have changed. Maybe it has
>> changed for real but you didn't have a chance to read it just yet.
>>
>>> +
>>> +   /* No need to proceed if we are going to do full detect */
>>> +   if (!ret || *perform_full_detect)
>>> return;
>>> -   }
>> So if you're returning because of !ret, *perform_full_detect may be true
>> or false, you don't know. I'd like the code to be explicit about what
>> you want the caller to do when intel_dp_get_dpcd returns false, full
>> detect or not.
>>
>> BR,
>> Jani.
> the idea i had in mind was if intel_dp_get_dpcd failed we should do a 
> full detect.
>
> my assumption here was that sink_count would be zero so it would take care
> of this, but now that it seems to be a wrong assumption how about the 
> following code ?
> this makes it explicit that if dpcd read failed we will do full detect.
>
> + if ((old_sink_count != intel_dp->sink_count) || !ret)
> + *perform_full_detect = true;
>
> +
> + /* No need to proceed if we are going to do full detect */
> + if (*perform_full_detect)
>   return;

Ok by me.

Jani.



>
>>
>>>   
>>> if (!intel_encoder->base.crtc)
>>> return;
>>> @@ -5031,13 +5044,17 @@ intel_dp_hpd_pulse(struct intel_digital_port 
>>> *intel_dig_port, bool long_hpd)
>>> }
>>>   
>>> if (!intel_dp->is_mst) {
>>> +   bool full_detect;
>>> /*
>>>  * we'll check the link status via the normal hot plug 
>>> path later -
>>>  * but for short hpds we should check it now
>>>  */
>>> drm_modeset_lock(>mode_config.connection_mutex, 
>>> NULL);
>>> -   intel_dp_check_link_status(intel_dp);
>>> +   intel_dp_check_link_status(intel_dp, _detect);
>>> drm_modeset_unlock(>mode_config.connection_mutex);
>>> +
>>> +   if (full_detect)
>>> +   goto put_power;
>>> }
>>> }
>>>   
>>> -- 
>>> 1.7.9.5
>>>
>
> -- 
> regards,
> Sivakumar
>

-- 
Jani Nikula, Intel Open Source Technology Center
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