[PATCH] drm: Update plane->fb also for page_flip

[PATCH] drm: Update plane->fb also for page_flip

[Daniel Vetter]

The legacy page_flip driver entry point is the only one left which
requires drivers to update plane->fb themselves. All the other entry
hooks will patch things up for the driver as needed since no one seems
to reliable get this right, see e.g. drm_mode_set_config_internal or
the plane->fb/old_fb handling in drm_mode_atomic_ioctl.

Therefore unify things, which allows us to ditch a TODO from
drm_atomic_helper_page_flip.

This should also help the atomic transition in i915 since we keep a
bit of legacy cruft only around because of this special behaviour in
->page_flip.

Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
---
 drivers/gpu/drm/drm_atomic_helper.c | 4 ----
 drivers/gpu/drm/drm_crtc.c          | 8 +-------
 2 files changed, 1 insertion(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index 5b59d5ad7d1c..0898afbc9e23 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -1915,10 +1915,6 @@ retry:
 	if (ret != 0)
 		goto fail;
 
-	/* TODO: ->page_flip is the only driver callback where the core
-	 * doesn't update plane->fb. For now patch it up here. */
-	plane->fb = plane->state->fb;
-
 	/* Driver takes ownership of state on successful async commit. */
 	return 0;
 fail:
diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index d15a96fdff43..ee0b3bf166b6 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -5345,13 +5345,7 @@ int drm_mode_page_flip_ioctl(struct drm_device *dev,
 		/* Keep the old fb, don't unref it. */
 		crtc->primary->old_fb = NULL;
 	} else {
-		/*
-		 * Warn if the driver hasn't properly updated the crtc->fb
-		 * field to reflect that the new framebuffer is now used.
-		 * Failing to do so will screw with the reference counting
-		 * on framebuffers.
-		 */
-		WARN_ON(crtc->primary->fb != fb);
+		crtc->primary->fb = fb;
 		/* Unref only the old framebuffer. */
 		fb = NULL;
 	}
-- 
2.1.4

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Re: [PATCH] drm: Update plane->fb also for page_flip

[Daniel Vetter]

On Tue, Jul 07, 2015 at 08:43:03AM +0200, Daniel Vetter wrote:
> The legacy page_flip driver entry point is the only one left which
> requires drivers to update plane->fb themselves. All the other entry
> hooks will patch things up for the driver as needed since no one seems
> to reliable get this right, see e.g. drm_mode_set_config_internal or
> the plane->fb/old_fb handling in drm_mode_atomic_ioctl.
> 
> Therefore unify things, which allows us to ditch a TODO from
> drm_atomic_helper_page_flip.
> 
> This should also help the atomic transition in i915 since we keep a
> bit of legacy cruft only around because of this special behaviour in
> ->page_flip.
> 
> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>

Applied with Maarten's irc r-b to drm-misc.
-Daniel

> ---
>  drivers/gpu/drm/drm_atomic_helper.c | 4 ----
>  drivers/gpu/drm/drm_crtc.c          | 8 +-------
>  2 files changed, 1 insertion(+), 11 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
> index 5b59d5ad7d1c..0898afbc9e23 100644
> --- a/drivers/gpu/drm/drm_atomic_helper.c
> +++ b/drivers/gpu/drm/drm_atomic_helper.c
> @@ -1915,10 +1915,6 @@ retry:
>  	if (ret != 0)
>  		goto fail;
>  
> -	/* TODO: ->page_flip is the only driver callback where the core
> -	 * doesn't update plane->fb. For now patch it up here. */
> -	plane->fb = plane->state->fb;
> -
>  	/* Driver takes ownership of state on successful async commit. */
>  	return 0;
>  fail:
> diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
> index d15a96fdff43..ee0b3bf166b6 100644
> --- a/drivers/gpu/drm/drm_crtc.c
> +++ b/drivers/gpu/drm/drm_crtc.c
> @@ -5345,13 +5345,7 @@ int drm_mode_page_flip_ioctl(struct drm_device *dev,
>  		/* Keep the old fb, don't unref it. */
>  		crtc->primary->old_fb = NULL;
>  	} else {
> -		/*
> -		 * Warn if the driver hasn't properly updated the crtc->fb
> -		 * field to reflect that the new framebuffer is now used.
> -		 * Failing to do so will screw with the reference counting
> -		 * on framebuffers.
> -		 */
> -		WARN_ON(crtc->primary->fb != fb);
> +		crtc->primary->fb = fb;
>  		/* Unref only the old framebuffer. */
>  		fb = NULL;
>  	}
> -- 
> 2.1.4
> 

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