[PATCH] drm/atomic: Add sanity checks to drm_atomic_helper_async_commit()

[PATCH] drm/atomic: Add sanity checks to drm_atomic_helper_async_commit()

[Boris Brezillon]

->atomic_async_update() requires that drivers update the plane->state
object before returning. Make sure at least common properties have been
updated.

Cc: Gustavo Padovan <gustavo@padovan.org>
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
---
Hello,

This is a problem I had when debugging the VC4 ->atomic_async_update()
implementation. The function was not updating plane->fb as it's
supposed thus leaving plane->state->fb in an inconsistent state after
each async update.

Not sure if such WARN_ON_ONCE() are accepted in the core though, so
I'll maintainers decide whether this is relevant or not and whether
they prefer to have WARN_ON() or DRM_ERROR() messages.

Regards,

Boris
---
 drivers/gpu/drm/drm_atomic_helper.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index c35654591c12..d2b2583487ee 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -1561,6 +1561,17 @@ void drm_atomic_helper_async_commit(struct drm_device *dev,
 	for_each_new_plane_in_state(state, plane, plane_state, i) {
 		funcs = plane->helper_private;
 		funcs->atomic_async_update(plane, plane_state);
+
+		/*
+		 * ->atomic_async_update() is supposed to update the
+		 * plane->state in-place, make sure at least common
+		 * properties have been properly updated.
+		 */
+		WARN_ON_ONCE(plane->state->fb != plane_state->fb);
+		WARN_ON_ONCE(plane->state->crtc_x != plane_state->crtc_x);
+		WARN_ON_ONCE(plane->state->crtc_y != plane_state->crtc_y);
+		WARN_ON_ONCE(plane->state->src_x != plane_state->src_x);
+		WARN_ON_ONCE(plane->state->src_y != plane_state->src_y);
 	}
 }
 EXPORT_SYMBOL(drm_atomic_helper_async_commit);
-- 
2.14.1

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Re: [PATCH] drm/atomic: Add sanity checks to drm_atomic_helper_async_commit()

[Eric Anholt]

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Boris Brezillon <boris.brezillon@bootlin.com> writes:

> ->atomic_async_update() requires that drivers update the plane->state
> object before returning. Make sure at least common properties have been
> updated.
>
> Cc: Gustavo Padovan <gustavo@padovan.org>
> Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
> ---
> Hello,
>
> This is a problem I had when debugging the VC4 ->atomic_async_update()
> implementation. The function was not updating plane->fb as it's
> supposed thus leaving plane->state->fb in an inconsistent state after
> each async update.
>
> Not sure if such WARN_ON_ONCE() are accepted in the core though, so
> I'll maintainers decide whether this is relevant or not and whether
> they prefer to have WARN_ON() or DRM_ERROR() messages.

I'm a huge fan of this kind of safety check.  FWIW,

Acked-by: Eric Anholt <eric@anholt.net>

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Re: [PATCH] drm/atomic: Add sanity checks to drm_atomic_helper_async_commit()

[Sean Paul]

On Fri, Mar 30, 2018 at 11:39:05AM -0700, Eric Anholt wrote:
> Boris Brezillon <boris.brezillon@bootlin.com> writes:
> 
> > ->atomic_async_update() requires that drivers update the plane->state
> > object before returning. Make sure at least common properties have been
> > updated.
> >
> > Cc: Gustavo Padovan <gustavo@padovan.org>
> > Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
> > ---
> > Hello,
> >
> > This is a problem I had when debugging the VC4 ->atomic_async_update()
> > implementation. The function was not updating plane->fb as it's
> > supposed thus leaving plane->state->fb in an inconsistent state after
> > each async update.
> >
> > Not sure if such WARN_ON_ONCE() are accepted in the core though, so
> > I'll maintainers decide whether this is relevant or not and whether
> > they prefer to have WARN_ON() or DRM_ERROR() messages.
> 
> I'm a huge fan of this kind of safety check.  FWIW,
> 
> Acked-by: Eric Anholt <eric@anholt.net>

Agreed, seems like a useful safety net to me.

Acked-by: Sean Paul <seanpaul@chromium.org>



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> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel


-- 
Sean Paul, Software Engineer, Google / Chromium OS
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Re: [PATCH] drm/atomic: Add sanity checks to drm_atomic_helper_async_commit()

[Daniel Vetter]

On Mon, Apr 02, 2018 at 11:45:31AM -0400, Sean Paul wrote:
> On Fri, Mar 30, 2018 at 11:39:05AM -0700, Eric Anholt wrote:
> > Boris Brezillon <boris.brezillon@bootlin.com> writes:
> > 
> > > ->atomic_async_update() requires that drivers update the plane->state
> > > object before returning. Make sure at least common properties have been
> > > updated.
> > >
> > > Cc: Gustavo Padovan <gustavo@padovan.org>
> > > Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
> > > ---
> > > Hello,
> > >
> > > This is a problem I had when debugging the VC4 ->atomic_async_update()
> > > implementation. The function was not updating plane->fb as it's
> > > supposed thus leaving plane->state->fb in an inconsistent state after
> > > each async update.
> > >
> > > Not sure if such WARN_ON_ONCE() are accepted in the core though, so
> > > I'll maintainers decide whether this is relevant or not and whether
> > > they prefer to have WARN_ON() or DRM_ERROR() messages.
> > 
> > I'm a huge fan of this kind of safety check.  FWIW,
> > 
> > Acked-by: Eric Anholt <eric@anholt.net>
> 
> Agreed, seems like a useful safety net to me.
> 
> Acked-by: Sean Paul <seanpaul@chromium.org>

Yeah, makes sense.

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

> 
> 
> 
> > _______________________________________________
> > dri-devel mailing list
> > dri-devel@lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/dri-devel
> 
> 
> -- 
> Sean Paul, Software Engineer, Google / Chromium OS

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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Re: [PATCH] drm/atomic: Add sanity checks to drm_atomic_helper_async_commit()

[Boris Brezillon]

On Fri, 30 Mar 2018 16:55:18 +0200
Boris Brezillon <boris.brezillon@bootlin.com> wrote:

> ->atomic_async_update() requires that drivers update the plane->state  
> object before returning. Make sure at least common properties have been
> updated.
> 
> Cc: Gustavo Padovan <gustavo@padovan.org>
> Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>

Applied to drm-misc-next.

> ---
> Hello,
> 
> This is a problem I had when debugging the VC4 ->atomic_async_update()
> implementation. The function was not updating plane->fb as it's
> supposed thus leaving plane->state->fb in an inconsistent state after
> each async update.
> 
> Not sure if such WARN_ON_ONCE() are accepted in the core though, so
> I'll maintainers decide whether this is relevant or not and whether
> they prefer to have WARN_ON() or DRM_ERROR() messages.
> 
> Regards,
> 
> Boris
> ---
>  drivers/gpu/drm/drm_atomic_helper.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
> index c35654591c12..d2b2583487ee 100644
> --- a/drivers/gpu/drm/drm_atomic_helper.c
> +++ b/drivers/gpu/drm/drm_atomic_helper.c
> @@ -1561,6 +1561,17 @@ void drm_atomic_helper_async_commit(struct drm_device *dev,
>  	for_each_new_plane_in_state(state, plane, plane_state, i) {
>  		funcs = plane->helper_private;
>  		funcs->atomic_async_update(plane, plane_state);
> +
> +		/*
> +		 * ->atomic_async_update() is supposed to update the
> +		 * plane->state in-place, make sure at least common
> +		 * properties have been properly updated.
> +		 */
> +		WARN_ON_ONCE(plane->state->fb != plane_state->fb);
> +		WARN_ON_ONCE(plane->state->crtc_x != plane_state->crtc_x);
> +		WARN_ON_ONCE(plane->state->crtc_y != plane_state->crtc_y);
> +		WARN_ON_ONCE(plane->state->src_x != plane_state->src_x);
> +		WARN_ON_ONCE(plane->state->src_y != plane_state->src_y);
>  	}
>  }
>  EXPORT_SYMBOL(drm_atomic_helper_async_commit);

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