Re: [PATCH 7/8] drm/vc4: kms: Remove async modeset semaphore

[Thomas Zimmermann <tzimmermann@xxxxxxx>]

Am 13.11.20 um 16:29 schrieb Maxime Ripard:
> Now that we have proper ordering guaranteed by the previous patch, the
> semaphore is redundant and can be removed.
>
> Signed-off-by: Maxime Ripard <maxime@xxxxxxxxxx>

Acked-by: Thomas Zimmermann <tzimmermann@xxxxxxx>

> ---
>   drivers/gpu/drm/vc4/vc4_crtc.c | 13 -------------
>   drivers/gpu/drm/vc4/vc4_drv.h  |  2 --
>   drivers/gpu/drm/vc4/vc4_kms.c  | 20 +-------------------
>   3 files changed, 1 insertion(+), 34 deletions(-)
>
> diff --git a/drivers/gpu/drm/vc4/vc4_crtc.c b/drivers/gpu/drm/vc4/vc4_crtc.c
> index 29b77f4b4e56..65d43e2e1d51 100644
> --- a/drivers/gpu/drm/vc4/vc4_crtc.c
> +++ b/drivers/gpu/drm/vc4/vc4_crtc.c
> @@ -699,7 +699,6 @@ vc4_async_page_flip_complete(struct vc4_seqno_cb *cb)
>   		container_of(cb, struct vc4_async_flip_state, cb);
>   	struct drm_crtc *crtc = flip_state->crtc;
>   	struct drm_device *dev = crtc->dev;
> -	struct vc4_dev *vc4 = to_vc4_dev(dev);
>   	struct drm_plane *plane = crtc->primary;
>   
>   	vc4_plane_async_set_fb(plane, flip_state->fb);
> @@ -731,8 +730,6 @@ vc4_async_page_flip_complete(struct vc4_seqno_cb *cb)
>   	}
>   
>   	kfree(flip_state);
> -
> -	up(&vc4->async_modeset);
>   }
>   
>   /* Implements async (non-vblank-synced) page flips.
> @@ -747,7 +744,6 @@ static int vc4_async_page_flip(struct drm_crtc *crtc,
>   			       uint32_t flags)
>   {
>   	struct drm_device *dev = crtc->dev;
> -	struct vc4_dev *vc4 = to_vc4_dev(dev);
>   	struct drm_plane *plane = crtc->primary;
>   	int ret = 0;
>   	struct vc4_async_flip_state *flip_state;
> @@ -776,15 +772,6 @@ static int vc4_async_page_flip(struct drm_crtc *crtc,
>   	flip_state->crtc = crtc;
>   	flip_state->event = event;
>   
> -	/* Make sure all other async modesetes have landed. */
> -	ret = down_interruptible(&vc4->async_modeset);
> -	if (ret) {
> -		drm_framebuffer_put(fb);
> -		vc4_bo_dec_usecnt(bo);
> -		kfree(flip_state);
> -		return ret;
> -	}
> -
>   	/* Save the current FB before it's replaced by the new one in
>   	 * drm_atomic_set_fb_for_plane(). We'll need the old FB in
>   	 * vc4_async_page_flip_complete() to decrement the BO usecnt and keep
> diff --git a/drivers/gpu/drm/vc4/vc4_drv.h b/drivers/gpu/drm/vc4/vc4_drv.h
> index 9eefd76cb09e..60062afba7b6 100644
> --- a/drivers/gpu/drm/vc4/vc4_drv.h
> +++ b/drivers/gpu/drm/vc4/vc4_drv.h
> @@ -215,8 +215,6 @@ struct vc4_dev {
>   		struct work_struct reset_work;
>   	} hangcheck;
>   
> -	struct semaphore async_modeset;
> -
>   	struct drm_modeset_lock ctm_state_lock;
>   	struct drm_private_obj ctm_manager;
>   	struct drm_private_obj hvs_channels;
> diff --git a/drivers/gpu/drm/vc4/vc4_kms.c b/drivers/gpu/drm/vc4/vc4_kms.c
> index 849bc6b4cea4..79ab7b8a5e0e 100644
> --- a/drivers/gpu/drm/vc4/vc4_kms.c
> +++ b/drivers/gpu/drm/vc4/vc4_kms.c
> @@ -414,8 +414,6 @@ vc4_atomic_complete_commit(struct drm_atomic_state *state)
>   		clk_set_min_rate(hvs->core_clk, 0);
>   
>   	drm_atomic_state_put(state);
> -
> -	up(&vc4->async_modeset);
>   }
>   
>   static void commit_work(struct work_struct *work)
> @@ -473,14 +471,9 @@ static int vc4_atomic_commit(struct drm_device *dev,
>   			     struct drm_atomic_state *state,
>   			     bool nonblock)
>   {
> -	struct vc4_dev *vc4 = to_vc4_dev(dev);
>   	int ret;
>   
>   	if (state->async_update) {
> -		ret = down_interruptible(&vc4->async_modeset);
> -		if (ret)
> -			return ret;
> -
>   		ret = drm_atomic_helper_prepare_planes(dev, state);
>   		if (ret) {
>   			up(&vc4->async_modeset);
> @@ -491,8 +484,6 @@ static int vc4_atomic_commit(struct drm_device *dev,
>   
>   		drm_atomic_helper_cleanup_planes(dev, state);
>   
> -		up(&vc4->async_modeset);
> -
>   		return 0;
>   	}
>   
> @@ -508,21 +499,14 @@ static int vc4_atomic_commit(struct drm_device *dev,
>   
>   	INIT_WORK(&state->commit_work, commit_work);
>   
> -	ret = down_interruptible(&vc4->async_modeset);
> -	if (ret)
> -		return ret;
> -
>   	ret = drm_atomic_helper_prepare_planes(dev, state);
> -	if (ret) {
> -		up(&vc4->async_modeset);
> +	if (ret)
>   		return ret;
> -	}
>   
>   	if (!nonblock) {
>   		ret = drm_atomic_helper_wait_for_fences(dev, state, true);
>   		if (ret) {
>   			drm_atomic_helper_cleanup_planes(dev, state);
> -			up(&vc4->async_modeset);
>   			return ret;
>   		}
>   	}
> @@ -1006,8 +990,6 @@ int vc4_kms_load(struct drm_device *dev)
>   		vc4->load_tracker_enabled = true;
>   	}
>   
> -	sema_init(&vc4->async_modeset, 1);
> -
>   	/* Set support for vblank irq fast disable, before drm_vblank_init() */
>   	dev->vblank_disable_immediate = true;
>   

--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer

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