[PATCH] drm/i915: Avoid stalling on pending flips for legacy cursor updates

[PATCH] drm/i915: Avoid stalling on pending flips for legacy cursor updates

[Chris Wilson]

The legacy cursor ioctl expects to be asynchronous with respect to other
screen updates, in particular page flips. As X updates the cursor from a
signal context, if the cursor blocks then it will stall both the input
and output chains causing bad stuttering and horrible UX.

Reported-and-tested-by: Rafael Ristovski <rafael.ristovski@gmail.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94980
Fixes: 5008e874edd34 ("drm/i915: Make wait_for_flips interruptible.")
Suggested-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: stable@vger.kernel.org
---
 drivers/gpu/drm/i915/intel_display.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 4cca155376be..c5b9687091f4 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -13446,6 +13446,9 @@ static int intel_atomic_prepare_commit(struct drm_device *dev,
 	}
 
 	for_each_crtc_in_state(state, crtc, crtc_state, i) {
+		if (state->legacy_cursor_update)
+			continue;
+
 		ret = intel_crtc_wait_for_pending_flips(crtc);
 		if (ret)
 			return ret;
-- 
2.8.0.rc3

Re: [PATCH] drm/i915: Avoid stalling on pending flips for legacy cursor updates

[Maarten Lankhorst]

Op 17-04-16 om 21:42 schreef Chris Wilson:
> The legacy cursor ioctl expects to be asynchronous with respect to other
> screen updates, in particular page flips. As X updates the cursor from a
> signal context, if the cursor blocks then it will stall both the input
> and output chains causing bad stuttering and horrible UX.
>
> Reported-and-tested-by: Rafael Ristovski <rafael.ristovski@gmail.com>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94980
> Fixes: 5008e874edd34 ("drm/i915: Make wait_for_flips interruptible.")
> Suggested-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Cc: Jani Nikula <jani.nikula@intel.com>
> Cc: stable@vger.kernel.org
> ---
>  drivers/gpu/drm/i915/intel_display.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 4cca155376be..c5b9687091f4 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -13446,6 +13446,9 @@ static int intel_atomic_prepare_commit(struct drm_device *dev,
>  	}
>  
>  	for_each_crtc_in_state(state, crtc, crtc_state, i) {
> +		if (state->legacy_cursor_update)
> +			continue;
> +
>  		ret = intel_crtc_wait_for_pending_flips(crtc);
>  		if (ret)
>  			return ret;
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>

Re: [PATCH] drm/i915: Avoid stalling on pending flips for legacy cursor updates

[Chris Wilson]

On Mon, Apr 18, 2016 at 12:02:15PM +0200, Maarten Lankhorst wrote:
> Op 17-04-16 om 21:42 schreef Chris Wilson:
> > The legacy cursor ioctl expects to be asynchronous with respect to other
> > screen updates, in particular page flips. As X updates the cursor from a
> > signal context, if the cursor blocks then it will stall both the input
> > and output chains causing bad stuttering and horrible UX.
> >
> > Reported-and-tested-by: Rafael Ristovski <rafael.ristovski@gmail.com>
> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94980
> > Fixes: 5008e874edd34 ("drm/i915: Make wait_for_flips interruptible.")
> > Suggested-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> > Cc: Ville Syrj�l� <ville.syrjala@linux.intel.com>
> > Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> > Cc: Jani Nikula <jani.nikula@intel.com>
> > Cc: stable@vger.kernel.org
> > ---
> >  drivers/gpu/drm/i915/intel_display.c | 3 +++
> >  1 file changed, 3 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> > index 4cca155376be..c5b9687091f4 100644
> > --- a/drivers/gpu/drm/i915/intel_display.c
> > +++ b/drivers/gpu/drm/i915/intel_display.c
> > @@ -13446,6 +13446,9 @@ static int intel_atomic_prepare_commit(struct drm_device *dev,
> >  	}
> >  
> >  	for_each_crtc_in_state(state, crtc, crtc_state, i) {
> > +		if (state->legacy_cursor_update)
> > +			continue;
> > +
> >  		ret = intel_crtc_wait_for_pending_flips(crtc);
> >  		if (ret)
> >  			return ret;
> Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>

Thanks, pushed.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre