[PATCH 3/7] drm/vc4: Mimic drm_atomic_helper_commit() behavior

[Eric Anholt]

Boris Brezillon <boris.brezillon at free-electrons.com> writes:

> The VC4 KMS driver is implementing its own ->atomic_commit() but there
> are a few generic helpers we can use instead of open-coding the logic.
>
> Signed-off-by: Boris Brezillon <boris.brezillon at free-electrons.com>
> ---
>  drivers/gpu/drm/vc4/vc4_kms.c | 38 ++++++++++++--------------------------
>  1 file changed, 12 insertions(+), 26 deletions(-)
>
> diff --git a/drivers/gpu/drm/vc4/vc4_kms.c b/drivers/gpu/drm/vc4/vc4_kms.c
> index ad7925a9e0ea..f229abc0991b 100644
> --- a/drivers/gpu/drm/vc4/vc4_kms.c
> +++ b/drivers/gpu/drm/vc4/vc4_kms.c
> @@ -42,6 +42,10 @@ vc4_atomic_complete_commit(struct vc4_commit *c)
>  	struct drm_device *dev = state->dev;
>  	struct vc4_dev *vc4 = to_vc4_dev(dev);
>  
> +	drm_atomic_helper_wait_for_fences(dev, state, false);
> +
> +	drm_atomic_helper_wait_for_dependencies(state);

With this wait_for_fences() addition and the reservation stuff that
landed, I think we can rip out the "seqno cb" in vc4, and just use
drm_atomic_helper_commit() and drm_atomic_hepler_commit_tail().  Do you
see anything missing, with that?

> +
>  	drm_atomic_helper_commit_modeset_disables(dev, state);
>  
>  	drm_atomic_helper_commit_planes(dev, state, 0);
> @@ -57,10 +61,14 @@ vc4_atomic_complete_commit(struct vc4_commit *c)
>  	 */
>  	state->legacy_cursor_update = false;
>  
> +	drm_atomic_helper_commit_hw_done(state);
> +
>  	drm_atomic_helper_wait_for_vblanks(dev, state);
>  
>  	drm_atomic_helper_cleanup_planes(dev, state);
>  
> +	drm_atomic_helper_commit_cleanup_done(state);
> +
>  	drm_atomic_state_put(state);
>  
>  	up(&vc4->async_modeset);
> @@ -117,32 +125,10 @@ static int vc4_atomic_commit(struct drm_device *dev,
>  	if (!c)
>  		return -ENOMEM;
>  
> -	/* Make sure that any outstanding modesets have finished. */
> -	if (nonblock) {
> -		struct drm_crtc *crtc;
> -		struct drm_crtc_state *crtc_state;
> -		unsigned long flags;
> -		bool busy = false;
> -
> -		/*
> -		 * If there's an undispatched event to send then we're
> -		 * obviously still busy.  If there isn't, then we can
> -		 * unconditionally wait for the semaphore because it
> -		 * shouldn't be contended (for long).
> -		 *
> -		 * This is to prevent a race where queuing a new flip
> -		 * from userspace immediately on receipt of an event
> -		 * beats our clean-up and returns EBUSY.
> -		 */
> -		spin_lock_irqsave(&dev->event_lock, flags);
> -		for_each_crtc_in_state(state, crtc, crtc_state, i)
> -			busy |= vc4_event_pending(crtc);
> -		spin_unlock_irqrestore(&dev->event_lock, flags);
> -		if (busy) {
> -			kfree(c);
> -			return -EBUSY;
> -		}
> -	}
> +	ret = drm_atomic_helper_setup_commit(state, nonblock);
> +	if (ret)
> +		return ret;
> +

Looks like vc4_event_pending() should be garbage-collected with this
commit.

>  	ret = down_interruptible(&vc4->async_modeset);
>  	if (ret) {
>  		kfree(c);
> -- 
> 2.7.4
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