Re: [PATCH v2 3/6] drm/mediatek: update cursors by using async atomic update

[CK Hu]

Hi, Bibby:

You move the mutex protection to [PATCH v2 6/6] drm/mediatek: apply CMDQ
control flow, but the race condition exist in this patch. So you should
move that back in this patch.

Regards,
CK

On Tue, 2019-12-03 at 15:10 +0800, Bibby Hsieh wrote:
> Support to async updates of cursors by using the new atomic
> interface for that.
> 
> Signed-off-by: Bibby Hsieh <bibby.hsieh@xxxxxxxxxxxx>
> ---
>  drivers/gpu/drm/mediatek/mtk_drm_crtc.c  | 33 ++++++++++++++++
>  drivers/gpu/drm/mediatek/mtk_drm_crtc.h  |  2 +
>  drivers/gpu/drm/mediatek/mtk_drm_plane.c | 50 ++++++++++++++++++++++++
>  drivers/gpu/drm/mediatek/mtk_drm_plane.h |  2 +
>  4 files changed, 87 insertions(+)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
> index 4c25ad2182b0..b23fe74b8b0a 100644
> --- a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
> +++ b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
> @@ -422,6 +422,39 @@ int mtk_drm_crtc_plane_check(struct drm_crtc *crtc, struct drm_plane *plane,
>  	return 0;
>  }
>  
> +void mtk_drm_crtc_async_update(struct drm_crtc *crtc, struct drm_plane *plane,
> +			       struct drm_plane_state *new_state)
> +{
> +	struct mtk_drm_private *priv = crtc->dev->dev_private;
> +	struct mtk_drm_crtc *mtk_crtc = to_mtk_crtc(crtc);
> +	const struct drm_plane_helper_funcs *plane_helper_funcs =
> +			plane->helper_private;
> +	int i;
> +
> +	if (!mtk_crtc->enabled)
> +		return;
> +
> +	plane_helper_funcs->atomic_update(plane, new_state);
> +
> +	for (i = 0; i < mtk_crtc->layer_nr; i++) {
> +		struct drm_plane *plane = &mtk_crtc->planes[i];
> +		struct mtk_plane_state *plane_state;
> +
> +		plane_state = to_mtk_plane_state(plane->state);
> +		if (plane_state->pending.async_dirty) {
> +			plane_state->pending.config = true;
> +			plane_state->pending.async_update = false;
> +			plane_state->pending.async_dirty = false;
> +		}
> +	}
> +	mtk_crtc->pending_planes = true;
> +	if (priv->data->shadow_register) {
> +		mtk_disp_mutex_acquire(mtk_crtc->mutex);
> +		mtk_crtc_ddp_config(crtc);
> +		mtk_disp_mutex_release(mtk_crtc->mutex);
> +	}
> +}
> +
>  static void mtk_drm_crtc_atomic_enable(struct drm_crtc *crtc,
>  				       struct drm_crtc_state *old_state)
>  {
> diff --git a/drivers/gpu/drm/mediatek/mtk_drm_crtc.h b/drivers/gpu/drm/mediatek/mtk_drm_crtc.h
> index 6afe1c19557a..a2b4677a451c 100644
> --- a/drivers/gpu/drm/mediatek/mtk_drm_crtc.h
> +++ b/drivers/gpu/drm/mediatek/mtk_drm_crtc.h
> @@ -21,5 +21,7 @@ int mtk_drm_crtc_create(struct drm_device *drm_dev,
>  			unsigned int path_len);
>  int mtk_drm_crtc_plane_check(struct drm_crtc *crtc, struct drm_plane *plane,
>  			     struct mtk_plane_state *state);
> +void mtk_drm_crtc_async_update(struct drm_crtc *crtc, struct drm_plane *plane,
> +			       struct drm_plane_state *plane_state);
>  
>  #endif /* MTK_DRM_CRTC_H */
> diff --git a/drivers/gpu/drm/mediatek/mtk_drm_plane.c b/drivers/gpu/drm/mediatek/mtk_drm_plane.c
> index cd7c97eb7ee6..6bdb42f068fb 100644
> --- a/drivers/gpu/drm/mediatek/mtk_drm_plane.c
> +++ b/drivers/gpu/drm/mediatek/mtk_drm_plane.c
> @@ -7,6 +7,7 @@
>  #include <drm/drm_atomic.h>
>  #include <drm/drm_atomic_helper.h>
>  #include <drm/drm_fourcc.h>
> +#include <drm/drm_atomic_uapi.h>
>  #include <drm/drm_plane_helper.h>
>  #include <drm/drm_gem_framebuffer_helper.h>
>  
> @@ -70,6 +71,50 @@ static void mtk_drm_plane_destroy_state(struct drm_plane *plane,
>  	kfree(to_mtk_plane_state(state));
>  }
>  
> +static int mtk_plane_atomic_async_check(struct drm_plane *plane,
> +					struct drm_plane_state *state)
> +{
> +	struct drm_crtc_state *crtc_state;
> +
> +	if (plane != state->crtc->cursor)
> +		return -EINVAL;
> +
> +	if (!plane->state)
> +		return -EINVAL;
> +
> +	if (!plane->state->fb)
> +		return -EINVAL;
> +
> +	if (state->state)
> +		crtc_state = drm_atomic_get_existing_crtc_state(state->state,
> +								state->crtc);
> +	else /* Special case for asynchronous cursor updates. */
> +		crtc_state = state->crtc->state;
> +
> +	return drm_atomic_helper_check_plane_state(plane->state, crtc_state,
> +						   DRM_PLANE_HELPER_NO_SCALING,
> +						   DRM_PLANE_HELPER_NO_SCALING,
> +						   true, true);
> +}
> +
> +static void mtk_plane_atomic_async_update(struct drm_plane *plane,
> +					  struct drm_plane_state *new_state)
> +{
> +	struct mtk_plane_state *state = to_mtk_plane_state(plane->state);
> +
> +	plane->state->crtc_x = new_state->crtc_x;
> +	plane->state->crtc_y = new_state->crtc_y;
> +	plane->state->crtc_h = new_state->crtc_h;
> +	plane->state->crtc_w = new_state->crtc_w;
> +	plane->state->src_x = new_state->src_x;
> +	plane->state->src_y = new_state->src_y;
> +	plane->state->src_h = new_state->src_h;
> +	plane->state->src_w = new_state->src_w;
> +	state->pending.async_update = true;
> +
> +	mtk_drm_crtc_async_update(new_state->crtc, plane, new_state);
> +}
> +
>  static const struct drm_plane_funcs mtk_plane_funcs = {
>  	.update_plane = drm_atomic_helper_update_plane,
>  	.disable_plane = drm_atomic_helper_disable_plane,
> @@ -141,6 +186,9 @@ static void mtk_plane_atomic_update(struct drm_plane *plane,
>  	state->pending.rotation = plane->state->rotation;
>  	wmb(); /* Make sure the above parameters are set before update */
>  	state->pending.dirty = true;
> +
> +	if (state->pending.async_update)
> +		state->pending.async_dirty = true;
>  }
>  
>  static void mtk_plane_atomic_disable(struct drm_plane *plane,
> @@ -158,6 +206,8 @@ static const struct drm_plane_helper_funcs mtk_plane_helper_funcs = {
>  	.atomic_check = mtk_plane_atomic_check,
>  	.atomic_update = mtk_plane_atomic_update,
>  	.atomic_disable = mtk_plane_atomic_disable,
> +	.atomic_async_update = mtk_plane_atomic_async_update,
> +	.atomic_async_check = mtk_plane_atomic_async_check,
>  };
>  
>  int mtk_plane_init(struct drm_device *dev, struct drm_plane *plane,
> diff --git a/drivers/gpu/drm/mediatek/mtk_drm_plane.h b/drivers/gpu/drm/mediatek/mtk_drm_plane.h
> index 760885e35b27..41882465dd67 100644
> --- a/drivers/gpu/drm/mediatek/mtk_drm_plane.h
> +++ b/drivers/gpu/drm/mediatek/mtk_drm_plane.h
> @@ -22,6 +22,8 @@ struct mtk_plane_pending_state {
>  	unsigned int			height;
>  	unsigned int			rotation;
>  	bool				dirty;
> +	bool				async_dirty;
> +	bool				async_update;
>  };
>  
>  struct mtk_plane_state {