[PATCH v2 07/12] drm/msm: Handle drm_atomic_helper_swap_state failure

[PATCH v2 07/12] drm/msm: Handle drm_atomic_helper_swap_state failure

[Maarten Lankhorst]

drm_atomic_helper_swap_state() will be changed to interruptible waiting
in the next few commits, so all drivers have to be changed to handling
failure.

MSM has its own busy tracking, which means the swap_state call can be
done with stall = false, in which case it should never return an error.
Handle failure with BUG_ON for this reason.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Rob Clark <robdclark@gmail.com>
Cc: linux-arm-msm@vger.kernel.org
Cc: freedreno@lists.freedesktop.org
---
 drivers/gpu/drm/msm/msm_atomic.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_atomic.c b/drivers/gpu/drm/msm/msm_atomic.c
index 9633a68b14d7..badfa8717317 100644
--- a/drivers/gpu/drm/msm/msm_atomic.c
+++ b/drivers/gpu/drm/msm/msm_atomic.c
@@ -232,20 +232,18 @@ int msm_atomic_commit(struct drm_device *dev,
 	 * mark our set of crtc's as busy:
 	 */
 	ret = start_atomic(dev->dev_private, c->crtc_mask);
-	if (ret) {
-		kfree(c);
-		goto error;
-	}
+	if (ret)
+		goto err_free;
+
+	BUG_ON(drm_atomic_helper_swap_state(state, false) < 0);
 
 	/*
 	 * This is the point of no return - everything below never fails except
 	 * when the hw goes bonghits. Which means we can commit the new state on
 	 * the software side now.
+	 *
+	 * swap driver private state while still holding state_lock
 	 */
-
-	drm_atomic_helper_swap_state(state, true);
-
-	/* swap driver private state while still holding state_lock */
 	if (to_kms_state(state)->state)
 		priv->kms->funcs->swap_state(priv->kms, state);
 
@@ -275,6 +273,8 @@ int msm_atomic_commit(struct drm_device *dev,
 
 	return 0;
 
+err_free:
+	kfree(c);
 error:
 	drm_atomic_helper_cleanup_planes(dev, state);
 	return ret;
-- 
2.11.0

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Re: [Intel-gfx] [PATCH v2 07/12] drm/msm: Handle drm_atomic_helper_swap_state failure

[Daniel Vetter]

On Tue, Jul 11, 2017 at 04:33:09PM +0200, Maarten Lankhorst wrote:
> drm_atomic_helper_swap_state() will be changed to interruptible waiting
> in the next few commits, so all drivers have to be changed to handling
> failure.
> 
> MSM has its own busy tracking, which means the swap_state call can be
> done with stall = false, in which case it should never return an error.
> Handle failure with BUG_ON for this reason.
> 
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Cc: Rob Clark <robdclark@gmail.com>
> Cc: linux-arm-msm@vger.kernel.org
> Cc: freedreno@lists.freedesktop.org
> ---
>  drivers/gpu/drm/msm/msm_atomic.c | 16 ++++++++--------
>  1 file changed, 8 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/msm_atomic.c b/drivers/gpu/drm/msm/msm_atomic.c
> index 9633a68b14d7..badfa8717317 100644
> --- a/drivers/gpu/drm/msm/msm_atomic.c
> +++ b/drivers/gpu/drm/msm/msm_atomic.c
> @@ -232,20 +232,18 @@ int msm_atomic_commit(struct drm_device *dev,
>  	 * mark our set of crtc's as busy:
>  	 */
>  	ret = start_atomic(dev->dev_private, c->crtc_mask);
> -	if (ret) {
> -		kfree(c);
> -		goto error;
> -	}
> +	if (ret)
> +		goto err_free;
> +
> +	BUG_ON(drm_atomic_helper_swap_state(state, false) < 0);

Hm, not sure we want to do this, makes switching msm to the nonblocking
helpers a bit more tricky. And the got err_free thing looks like leftovers
from an old version. But it's all correct.

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

>  
>  	/*
>  	 * This is the point of no return - everything below never fails except
>  	 * when the hw goes bonghits. Which means we can commit the new state on
>  	 * the software side now.
> +	 *
> +	 * swap driver private state while still holding state_lock
>  	 */
> -
> -	drm_atomic_helper_swap_state(state, true);
> -
> -	/* swap driver private state while still holding state_lock */
>  	if (to_kms_state(state)->state)
>  		priv->kms->funcs->swap_state(priv->kms, state);
>  
> @@ -275,6 +273,8 @@ int msm_atomic_commit(struct drm_device *dev,
>  
>  	return 0;
>  
> +err_free:
> +	kfree(c);
>  error:
>  	drm_atomic_helper_cleanup_planes(dev, state);
>  	return ret;
> -- 
> 2.11.0
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx

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