[PATCH] drm/i915: intel_hpd_init(): Don't check connectors for an encoder

[PATCH] drm/i915: intel_hpd_init(): Don't check connectors for an encoder

[Lyude]

There's no reason to check for an active encoder when setting up hpd,
especially since a disconnected connector isn't going to have an encoder
in the first place. This fixes reprobing display connectors on resume.

Signed-off-by: Lyude <cpaul@redhat.com>
---
After some talking with danvet on IRC, I learned that calling
drm_helper_hpd_irq_event() does actually trigger a full reprobe of each
connector's status. It turns out this is the actual reason reprobing on resume
hasn't been working (this was observed on a T440s):

	- We call hpd_init()
	- We check each connector for a couple of things before marking
	  connector->polled with DRM_CONNECTOR_POLL_HPD, one of which is an
	  active encoder. Of course, a disconnected port won't have an active
	  encoder, so we don't add the flag to any of the connector's.
	- We call drm_helper_hpd_irq_event()
	- drm_helper_irq_event() checks each connector for the
	  DRM_CONNECTOR_POLL_HPD flag. The only one that has it is eDP-1, so we
	  skip reprobing each connector except that one.

 drivers/gpu/drm/i915/intel_hotplug.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_hotplug.c b/drivers/gpu/drm/i915/intel_hotplug.c
index b177857..18797bc 100644
--- a/drivers/gpu/drm/i915/intel_hotplug.c
+++ b/drivers/gpu/drm/i915/intel_hotplug.c
@@ -468,7 +468,7 @@ void intel_hpd_init(struct drm_i915_private *dev_priv)
 	list_for_each_entry(connector, &mode_config->connector_list, head) {
 		struct intel_connector *intel_connector = to_intel_connector(connector);
 		connector->polled = intel_connector->polled;
-		if (connector->encoder && !connector->polled && I915_HAS_HOTPLUG(dev) && intel_connector->encoder->hpd_pin > HPD_NONE)
+		if (!connector->polled && I915_HAS_HOTPLUG(dev) && intel_connector->encoder->hpd_pin > HPD_NONE)
 			connector->polled = DRM_CONNECTOR_POLL_HPD;
 		if (intel_connector->mst_port)
 			connector->polled = DRM_CONNECTOR_POLL_HPD;
-- 
2.5.0

Re: [Intel-gfx] [PATCH] drm/i915: intel_hpd_init(): Don't check connectors for an encoder

[Daniel Vetter]

On Tue, Jan 05, 2016 at 02:53:08PM -0500, Lyude wrote:
> There's no reason to check for an active encoder when setting up hpd,
> especially since a disconnected connector isn't going to have an encoder
> in the first place. This fixes reprobing display connectors on resume.
> 
> Signed-off-by: Lyude <cpaul@redhat.com>
> ---
> After some talking with danvet on IRC, I learned that calling
> drm_helper_hpd_irq_event() does actually trigger a full reprobe of each
> connector's status. It turns out this is the actual reason reprobing on resume
> hasn't been working (this was observed on a T440s):
> 
> 	- We call hpd_init()
> 	- We check each connector for a couple of things before marking
> 	  connector->polled with DRM_CONNECTOR_POLL_HPD, one of which is an
> 	  active encoder. Of course, a disconnected port won't have an active
> 	  encoder, so we don't add the flag to any of the connector's.
> 	- We call drm_helper_hpd_irq_event()
> 	- drm_helper_irq_event() checks each connector for the
> 	  DRM_CONNECTOR_POLL_HPD flag. The only one that has it is eDP-1, so we
> 	  skip reprobing each connector except that one.

The above explanation should be part of the commit message, otherwise it's
hard to understand the impact of this fix.

Fixes: 0e32b39ceed6 ("drm/i915: add DP 1.2 MST support (v0.7)")
Cc: stable@vger.kernel.org

Unfortunately Dave doesn't explain in his MST commit why he's done this.
Dave? I can't come up with a reason, but better to test that. Lyude?

Anyway looks good to me.

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

> 
>  drivers/gpu/drm/i915/intel_hotplug.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_hotplug.c b/drivers/gpu/drm/i915/intel_hotplug.c
> index b177857..18797bc 100644
> --- a/drivers/gpu/drm/i915/intel_hotplug.c
> +++ b/drivers/gpu/drm/i915/intel_hotplug.c
> @@ -468,7 +468,7 @@ void intel_hpd_init(struct drm_i915_private *dev_priv)
>  	list_for_each_entry(connector, &mode_config->connector_list, head) {
>  		struct intel_connector *intel_connector = to_intel_connector(connector);
>  		connector->polled = intel_connector->polled;
> -		if (connector->encoder && !connector->polled && I915_HAS_HOTPLUG(dev) && intel_connector->encoder->hpd_pin > HPD_NONE)
> +		if (!connector->polled && I915_HAS_HOTPLUG(dev) && intel_connector->encoder->hpd_pin > HPD_NONE)
>  			connector->polled = DRM_CONNECTOR_POLL_HPD;
>  		if (intel_connector->mst_port)
>  			connector->polled = DRM_CONNECTOR_POLL_HPD;
> -- 
> 2.5.0
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

Re: [Intel-gfx] [PATCH] drm/i915: intel_hpd_init(): Don't check connectors for an encoder

[Daniel Vetter]

On Tue, Jan 05, 2016 at 09:05:49PM +0100, Daniel Vetter wrote:
> On Tue, Jan 05, 2016 at 02:53:08PM -0500, Lyude wrote:
> > There's no reason to check for an active encoder when setting up hpd,
> > especially since a disconnected connector isn't going to have an encoder
> > in the first place. This fixes reprobing display connectors on resume.
> > 
> > Signed-off-by: Lyude <cpaul@redhat.com>
> > ---
> > After some talking with danvet on IRC, I learned that calling
> > drm_helper_hpd_irq_event() does actually trigger a full reprobe of each
> > connector's status. It turns out this is the actual reason reprobing on resume
> > hasn't been working (this was observed on a T440s):
> > 
> > 	- We call hpd_init()
> > 	- We check each connector for a couple of things before marking
> > 	  connector->polled with DRM_CONNECTOR_POLL_HPD, one of which is an
> > 	  active encoder. Of course, a disconnected port won't have an active
> > 	  encoder, so we don't add the flag to any of the connector's.
> > 	- We call drm_helper_hpd_irq_event()
> > 	- drm_helper_irq_event() checks each connector for the
> > 	  DRM_CONNECTOR_POLL_HPD flag. The only one that has it is eDP-1, so we
> > 	  skip reprobing each connector except that one.
> 
> The above explanation should be part of the commit message, otherwise it's
> hard to understand the impact of this fix.
> 
> Fixes: 0e32b39ceed6 ("drm/i915: add DP 1.2 MST support (v0.7)")
> Cc: stable@vger.kernel.org
> 
> Unfortunately Dave doesn't explain in his MST commit why he's done this.
> Dave? I can't come up with a reason, but better to test that. Lyude?
> 
> Anyway looks good to me.
> 
> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Need to retract my r-b. MST connectors don't have a fixed fake encoder,
and the intel_connector->encoder link is done at link time and not static.

We need to filter out MST connectors here, otherwise this will go boom.
While at it, can you please line-break this properly to appease
checkpatch?
-Daniel

> 
> > 
> >  drivers/gpu/drm/i915/intel_hotplug.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_hotplug.c b/drivers/gpu/drm/i915/intel_hotplug.c
> > index b177857..18797bc 100644
> > --- a/drivers/gpu/drm/i915/intel_hotplug.c
> > +++ b/drivers/gpu/drm/i915/intel_hotplug.c
> > @@ -468,7 +468,7 @@ void intel_hpd_init(struct drm_i915_private *dev_priv)
> >  	list_for_each_entry(connector, &mode_config->connector_list, head) {
> >  		struct intel_connector *intel_connector = to_intel_connector(connector);
> >  		connector->polled = intel_connector->polled;
> > -		if (connector->encoder && !connector->polled && I915_HAS_HOTPLUG(dev) && intel_connector->encoder->hpd_pin > HPD_NONE)
> > +		if (!connector->polled && I915_HAS_HOTPLUG(dev) && intel_connector->encoder->hpd_pin > HPD_NONE)
> >  			connector->polled = DRM_CONNECTOR_POLL_HPD;
> >  		if (intel_connector->mst_port)
> >  			connector->polled = DRM_CONNECTOR_POLL_HPD;
> > -- 
> > 2.5.0
> > 
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx@lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

[PATCH v2] drm/i915: intel_hpd_init(): Fix suspend/resume reprobing

[Lyude]

This fixes reprobing of display connectors on resume. After some talking
with danvet on IRC, I learned that calling drm_helper_hpd_irq_event() does
actually trigger a full reprobe of each connector's status. It turns out
this is the actual reason reprobing on resume hasn't been working (this was
observed on a T440s):

	- We call hpd_init()
	- We check each connector for a couple of things before marking
	  connector->polled with DRM_CONNECTOR_POLL_HPD, one of which is an
	  active encoder. Of course, a disconnected port won't have an
	  active encoder, so we don't add the flag to any of the
	  connectors.
	- We call drm_helper_hpd_irq_event()
	- drm_helper_irq_event() checks each connector for the
	  DRM_CONNECTOR_POLL_HPD flag. The only one that has it is eDP-1,
	  so we skip reprobing each connector except for that one.

In addition, we now avoid setting connector->polled to
DRM_CONNECTOR_POLL_HPD for MST connectors, since their reprobing is handled
by the mst helpers. This is probably what was originally intended to happen
here anyway.

Fixes: 0e32b39ceed6 ("drm/i915: add DP 1.2 MST support (v0.7)")
Cc: stable@vger.kernel.org
Signed-off-by: Lyude <cpaul@redhat.com>
---
				    Changes
* Use the explanation of the issue as the commit message instead
* Change the title of the commit, since this does more then just stop a check
  for an encoder now
* Add "Fixes" line for the patch that introduced this regression
* Don't enable DRM_CONNECTOR_POLL_HPD for mst connectors

 drivers/gpu/drm/i915/intel_hotplug.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_hotplug.c b/drivers/gpu/drm/i915/intel_hotplug.c
index b177857..51ecf0b4 100644
--- a/drivers/gpu/drm/i915/intel_hotplug.c
+++ b/drivers/gpu/drm/i915/intel_hotplug.c
@@ -468,9 +468,9 @@ void intel_hpd_init(struct drm_i915_private *dev_priv)
 	list_for_each_entry(connector, &mode_config->connector_list, head) {
 		struct intel_connector *intel_connector = to_intel_connector(connector);
 		connector->polled = intel_connector->polled;
-		if (connector->encoder && !connector->polled && I915_HAS_HOTPLUG(dev) && intel_connector->encoder->hpd_pin > HPD_NONE)
-			connector->polled = DRM_CONNECTOR_POLL_HPD;
-		if (intel_connector->mst_port)
+		if (!connector->polled && !intel_connector->mst_port &&
+		    I915_HAS_HOTPLUG(dev) &&
+		    intel_connector->encoder->hpd_pin > HPD_NONE)
 			connector->polled = DRM_CONNECTOR_POLL_HPD;
 	}
 
-- 
2.5.0

Re: [Intel-gfx] [PATCH v2] drm/i915: intel_hpd_init(): Fix suspend/resume reprobing

[Daniel Vetter]

On Tue, Jan 05, 2016 at 04:15:30PM -0500, Lyude wrote:
> This fixes reprobing of display connectors on resume. After some talking
> with danvet on IRC, I learned that calling drm_helper_hpd_irq_event() does
> actually trigger a full reprobe of each connector's status. It turns out
> this is the actual reason reprobing on resume hasn't been working (this was
> observed on a T440s):
> 
> 	- We call hpd_init()
> 	- We check each connector for a couple of things before marking
> 	  connector->polled with DRM_CONNECTOR_POLL_HPD, one of which is an
> 	  active encoder. Of course, a disconnected port won't have an
> 	  active encoder, so we don't add the flag to any of the
> 	  connectors.
> 	- We call drm_helper_hpd_irq_event()
> 	- drm_helper_irq_event() checks each connector for the
> 	  DRM_CONNECTOR_POLL_HPD flag. The only one that has it is eDP-1,
> 	  so we skip reprobing each connector except for that one.
> 
> In addition, we now avoid setting connector->polled to
> DRM_CONNECTOR_POLL_HPD for MST connectors, since their reprobing is handled
> by the mst helpers. This is probably what was originally intended to happen
> here anyway.
> 
> Fixes: 0e32b39ceed6 ("drm/i915: add DP 1.2 MST support (v0.7)")
> Cc: stable@vger.kernel.org
> Signed-off-by: Lyude <cpaul@redhat.com>
> ---
> 				    Changes
> * Use the explanation of the issue as the commit message instead
> * Change the title of the commit, since this does more then just stop a check
>   for an encoder now
> * Add "Fixes" line for the patch that introduced this regression
> * Don't enable DRM_CONNECTOR_POLL_HPD for mst connectors

For drm/i915 I prefer when the patch changelog is above the s-o-b section,
with v2: v3: ... headings.
> 
>  drivers/gpu/drm/i915/intel_hotplug.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_hotplug.c b/drivers/gpu/drm/i915/intel_hotplug.c
> index b177857..51ecf0b4 100644
> --- a/drivers/gpu/drm/i915/intel_hotplug.c
> +++ b/drivers/gpu/drm/i915/intel_hotplug.c
> @@ -468,9 +468,9 @@ void intel_hpd_init(struct drm_i915_private *dev_priv)
>  	list_for_each_entry(connector, &mode_config->connector_list, head) {
>  		struct intel_connector *intel_connector = to_intel_connector(connector);
>  		connector->polled = intel_connector->polled;
> -		if (connector->encoder && !connector->polled && I915_HAS_HOTPLUG(dev) && intel_connector->encoder->hpd_pin > HPD_NONE)
> -			connector->polled = DRM_CONNECTOR_POLL_HPD;
> -		if (intel_connector->mst_port)
> +		if (!connector->polled && !intel_connector->mst_port &&
> +		    I915_HAS_HOTPLUG(dev) &&
> +		    intel_connector->encoder->hpd_pin > HPD_NONE)
>  			connector->polled = DRM_CONNECTOR_POLL_HPD;

Hm, on 2nd thought we could clarify this further like this:

	list_for_each_entry(...) {
		...
		
		/* MST has a dynamic intel_connector->encoder and it's
		 * reprobing is all handled by the MST helpers. */
		if (intel_connector->mst_port)
			continue;

		if (!connector->polled && I915_HAS_HOTPLUG(dev) &&
		    intel_connector->encoder->hpd_pin > HPD_NONE)
			connector->polled = DRM_CONNECTOR_POLL_HPD;

	}

That yields even tidier code and gives us a place for a comment. Can you
pls respin once more?

Thanks, Daniel

>  	}
>  
> -- 
> 2.5.0
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

[PATCH v3] drm/i915: intel_hpd_init(): Fix suspend/resume reprobing

[Lyude]

This fixes reprobing of display connectors on resume.  After some
talking with danvet on IRC, I learned that calling
drm_helper_hpd_irq_event() does actually trigger a full reprobe of each
connector's status. It turns out this is the actual reason reprobing on
resume hasn't been working (this was observed on a T440s):

	- We call hpd_init()
	- We check each connector for a couple of things before marking
	  connector->polled with DRM_CONNECTOR_POLL_HPD, one of which is an
	  active encoder. Of course, a disconnected port won't have an
	  active encoder, so we don't add the flag to any of the
	  connectors.
	- We call drm_helper_hpd_irq_event()
	- drm_helper_irq_event() checks each connector for the
	  DRM_CONNECTOR_POLL_HPD flag. The only one that has it is eDP-1,
	  so we skip reprobing each connector except that one.

In addition, we also now avoid setting connector->polled to
DRM_CONNECTOR_POLL_HPD for MST connectors, since their reprobing is
handled by the mst helpers. This is probably what was originally
intended to happen here.

Changes since V1:
* Use the explanation of the issue as the commit message instead
* Change the title of the commit, since this does more then just stop a
  check for an encoder now
* Add "Fixes" line for the patch that introduced this regression
* Don't enable DRM_CONNECTOR_POLL_HPD for mst connectors

Changes since V2:
* Put patch changelog above Signed-off-by
* Follow Daniel Vetter's suggestion for making the code here a bit more
  legible

Fixes: 0e32b39ceed6 ("drm/i915: add DP 1.2 MST support (v0.7)")
Cc: stable@vger.kernel.org
Signed-off-by: Lyude <cpaul@redhat.com>
---
 drivers/gpu/drm/i915/intel_hotplug.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_hotplug.c b/drivers/gpu/drm/i915/intel_hotplug.c
index b177857..d7a6437 100644
--- a/drivers/gpu/drm/i915/intel_hotplug.c
+++ b/drivers/gpu/drm/i915/intel_hotplug.c
@@ -468,9 +468,14 @@ void intel_hpd_init(struct drm_i915_private *dev_priv)
 	list_for_each_entry(connector, &mode_config->connector_list, head) {
 		struct intel_connector *intel_connector = to_intel_connector(connector);
 		connector->polled = intel_connector->polled;
-		if (connector->encoder && !connector->polled && I915_HAS_HOTPLUG(dev) && intel_connector->encoder->hpd_pin > HPD_NONE)
-			connector->polled = DRM_CONNECTOR_POLL_HPD;
+
+		/* MST has a dynamic intel_connector->encoder and it's reprobing
+		 * is all handled by the MST helpers. */
 		if (intel_connector->mst_port)
+			continue;
+
+		if (!connector->polled && I915_HAS_HOTPLUG(dev) &&
+		    intel_connector->encoder->hpd_pin > HPD_NONE)
 			connector->polled = DRM_CONNECTOR_POLL_HPD;
 	}
 
-- 
2.5.0

Re: [Intel-gfx] [PATCH v3] drm/i915: intel_hpd_init(): Fix suspend/resume reprobing

[Daniel Vetter]

On Thu, Jan 07, 2016 at 10:43:28AM -0500, Lyude wrote:
> This fixes reprobing of display connectors on resume.  After some
> talking with danvet on IRC, I learned that calling
> drm_helper_hpd_irq_event() does actually trigger a full reprobe of each
> connector's status. It turns out this is the actual reason reprobing on
> resume hasn't been working (this was observed on a T440s):
> 
> 	- We call hpd_init()
> 	- We check each connector for a couple of things before marking
> 	  connector->polled with DRM_CONNECTOR_POLL_HPD, one of which is an
> 	  active encoder. Of course, a disconnected port won't have an
> 	  active encoder, so we don't add the flag to any of the
> 	  connectors.
> 	- We call drm_helper_hpd_irq_event()
> 	- drm_helper_irq_event() checks each connector for the
> 	  DRM_CONNECTOR_POLL_HPD flag. The only one that has it is eDP-1,
> 	  so we skip reprobing each connector except that one.
> 
> In addition, we also now avoid setting connector->polled to
> DRM_CONNECTOR_POLL_HPD for MST connectors, since their reprobing is
> handled by the mst helpers. This is probably what was originally
> intended to happen here.
> 
> Changes since V1:
> * Use the explanation of the issue as the commit message instead
> * Change the title of the commit, since this does more then just stop a
>   check for an encoder now
> * Add "Fixes" line for the patch that introduced this regression
> * Don't enable DRM_CONNECTOR_POLL_HPD for mst connectors
> 
> Changes since V2:
> * Put patch changelog above Signed-off-by
> * Follow Daniel Vetter's suggestion for making the code here a bit more
>   legible
> 
> Fixes: 0e32b39ceed6 ("drm/i915: add DP 1.2 MST support (v0.7)")
> Cc: stable@vger.kernel.org
> Signed-off-by: Lyude <cpaul@redhat.com>

Awesome, and merged to drm-intel.

Thanks, Daniel

> ---
>  drivers/gpu/drm/i915/intel_hotplug.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_hotplug.c b/drivers/gpu/drm/i915/intel_hotplug.c
> index b177857..d7a6437 100644
> --- a/drivers/gpu/drm/i915/intel_hotplug.c
> +++ b/drivers/gpu/drm/i915/intel_hotplug.c
> @@ -468,9 +468,14 @@ void intel_hpd_init(struct drm_i915_private *dev_priv)
>  	list_for_each_entry(connector, &mode_config->connector_list, head) {
>  		struct intel_connector *intel_connector = to_intel_connector(connector);
>  		connector->polled = intel_connector->polled;
> -		if (connector->encoder && !connector->polled && I915_HAS_HOTPLUG(dev) && intel_connector->encoder->hpd_pin > HPD_NONE)
> -			connector->polled = DRM_CONNECTOR_POLL_HPD;
> +
> +		/* MST has a dynamic intel_connector->encoder and it's reprobing
> +		 * is all handled by the MST helpers. */
>  		if (intel_connector->mst_port)
> +			continue;
> +
> +		if (!connector->polled && I915_HAS_HOTPLUG(dev) &&
> +		    intel_connector->encoder->hpd_pin > HPD_NONE)
>  			connector->polled = DRM_CONNECTOR_POLL_HPD;
>  	}
>  
> -- 
> 2.5.0
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch