linux-kernel - Re: [PATCH 3/4] drm/vc4: Use the atomic state's commit workqueue.

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Message-ID: <20170622100604.4c3b93fd@bbrezillon>
Date:   Thu, 22 Jun 2017 10:06:04 +0200
From:   Boris Brezillon <boris.brezillon@...e-electrons.com>
To:     Eric Anholt <eric@...olt.net>
Cc:     dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/4] drm/vc4: Use the atomic state's commit workqueue.

On Wed, 21 Jun 2017 11:50:01 -0700
Eric Anholt <eric@...olt.net> wrote:

> Now that we're using the atomic helpers for fence waits, we can use
> the same codepath as drm_atomic_helper_commit() does for async,
> getting rid of our custom vc4_commit struct.
> 
> Signed-off-by: Eric Anholt <eric@...olt.net>

Reviewed-by: Boris Brezillon <boris.brezillon@...e-electrons.com>

And with this rework, you also fix the leak I introduced in commit
34c8ea400ff6 ("drm/vc4: Mimic drm_atomic_helper_commit() behavior").

> ---
>  drivers/gpu/drm/vc4/vc4_kms.c | 71 ++++++++-----------------------------------
>  1 file changed, 13 insertions(+), 58 deletions(-)
> 
> diff --git a/drivers/gpu/drm/vc4/vc4_kms.c b/drivers/gpu/drm/vc4/vc4_kms.c
> index 6b1ccea76243..b371879c3901 100644
> --- a/drivers/gpu/drm/vc4/vc4_kms.c
> +++ b/drivers/gpu/drm/vc4/vc4_kms.c
> @@ -29,16 +29,9 @@ static void vc4_output_poll_changed(struct drm_device *dev)
>  	drm_fbdev_cma_hotplug_event(vc4->fbdev);
>  }
>  
> -struct vc4_commit {
> -	struct drm_device *dev;
> -	struct drm_atomic_state *state;
> -	struct vc4_seqno_cb cb;
> -};
> -
>  static void
> -vc4_atomic_complete_commit(struct vc4_commit *c)
> +vc4_atomic_complete_commit(struct drm_atomic_state *state)
>  {
> -	struct drm_atomic_state *state = c->state;
>  	struct drm_device *dev = state->dev;
>  	struct vc4_dev *vc4 = to_vc4_dev(dev);
>  
> @@ -72,28 +65,14 @@ vc4_atomic_complete_commit(struct vc4_commit *c)
>  	drm_atomic_state_put(state);
>  
>  	up(&vc4->async_modeset);
> -
> -	kfree(c);
> -}
> -
> -static void
> -vc4_atomic_complete_commit_seqno_cb(struct vc4_seqno_cb *cb)
> -{
> -	struct vc4_commit *c = container_of(cb, struct vc4_commit, cb);
> -
> -	vc4_atomic_complete_commit(c);
>  }
>  
> -static struct vc4_commit *commit_init(struct drm_atomic_state *state)
> +static void commit_work(struct work_struct *work)
>  {
> -	struct vc4_commit *c = kzalloc(sizeof(*c), GFP_KERNEL);
> -
> -	if (!c)
> -		return NULL;
> -	c->dev = state->dev;
> -	c->state = state;
> -
> -	return c;
> +	struct drm_atomic_state *state = container_of(work,
> +						      struct drm_atomic_state,
> +						      commit_work);
> +	vc4_atomic_complete_commit(state);
>  }
>  
>  /**
> @@ -115,29 +94,19 @@ static int vc4_atomic_commit(struct drm_device *dev,
>  {
>  	struct vc4_dev *vc4 = to_vc4_dev(dev);
>  	int ret;
> -	int i;
> -	uint64_t wait_seqno = 0;
> -	struct vc4_commit *c;
> -	struct drm_plane *plane;
> -	struct drm_plane_state *new_state;
> -
> -	c = commit_init(state);
> -	if (!c)
> -		return -ENOMEM;
>  
>  	ret = drm_atomic_helper_setup_commit(state, nonblock);
>  	if (ret)
>  		return ret;
>  
> +	INIT_WORK(&state->commit_work, commit_work);
> +
>  	ret = down_interruptible(&vc4->async_modeset);
> -	if (ret) {
> -		kfree(c);
> +	if (ret)
>  		return ret;
> -	}
>  
>  	ret = drm_atomic_helper_prepare_planes(dev, state);
>  	if (ret) {
> -		kfree(c);
>  		up(&vc4->async_modeset);
>  		return ret;
>  	}
> @@ -146,22 +115,11 @@ static int vc4_atomic_commit(struct drm_device *dev,
>  		ret = drm_atomic_helper_wait_for_fences(dev, state, true);
>  		if (ret) {
>  			drm_atomic_helper_cleanup_planes(dev, state);
> -			kfree(c);
>  			up(&vc4->async_modeset);
>  			return ret;
>  		}
>  	}
>  
> -	for_each_plane_in_state(state, plane, new_state, i) {
> -		if ((plane->state->fb != new_state->fb) && new_state->fb) {
> -			struct drm_gem_cma_object *cma_bo =
> -				drm_fb_cma_get_gem_obj(new_state->fb, 0);
> -			struct vc4_bo *bo = to_vc4_bo(&cma_bo->base);
> -
> -			wait_seqno = max(bo->seqno, wait_seqno);
> -		}
> -	}
> -
>  	/*
>  	 * 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
> @@ -187,13 +145,10 @@ static int vc4_atomic_commit(struct drm_device *dev,
>  	 */
>  
>  	drm_atomic_state_get(state);
> -	if (nonblock) {
> -		vc4_queue_seqno_cb(dev, &c->cb, wait_seqno,
> -				   vc4_atomic_complete_commit_seqno_cb);
> -	} else {
> -		vc4_wait_for_seqno(dev, wait_seqno, ~0ull, false);
> -		vc4_atomic_complete_commit(c);
> -	}
> +	if (nonblock)
> +		queue_work(system_unbound_wq, &state->commit_work);
> +	else
> +		vc4_atomic_complete_commit(state);
>  
>  	return 0;
>  }