[PATCH 24/28] drm: use new iterator in drm_gem_plane_helper_prepare_fb v2

[Daniel Vetter]

On Tue, Oct 05, 2021 at 01:37:38PM +0200, Christian König wrote:
> Makes the handling a bit more complex, but avoids the use of
> dma_resv_get_excl_unlocked().
> 
> v2: improve coding and documentation
> 
> Signed-off-by: Christian König <christian.koenig at amd.com>
> ---
>  drivers/gpu/drm/drm_gem_atomic_helper.c | 13 +++++++++++--
>  1 file changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_gem_atomic_helper.c b/drivers/gpu/drm/drm_gem_atomic_helper.c
> index e570398abd78..8534f78d4d6d 100644
> --- a/drivers/gpu/drm/drm_gem_atomic_helper.c
> +++ b/drivers/gpu/drm/drm_gem_atomic_helper.c
> @@ -143,6 +143,7 @@
>   */
>  int drm_gem_plane_helper_prepare_fb(struct drm_plane *plane, struct drm_plane_state *state)
>  {
> +	struct dma_resv_iter cursor;
>  	struct drm_gem_object *obj;
>  	struct dma_fence *fence;
>  
> @@ -150,9 +151,17 @@ int drm_gem_plane_helper_prepare_fb(struct drm_plane *plane, struct drm_plane_st
>  		return 0;
>  
>  	obj = drm_gem_fb_get_obj(state->fb, 0);
> -	fence = dma_resv_get_excl_unlocked(obj->resv);
> -	drm_atomic_set_fence_for_plane(state, fence);
> +	dma_resv_iter_begin(&cursor, obj->resv, false);
> +	dma_resv_for_each_fence_unlocked(&cursor, fence) {
> +		/* TODO: We only use the first write fence here and need to fix

Maybe reword the todo that currently there's only one write fence, and if
that changes we have work to do. Or something like that. The current
comments sounds like multiple write fences are possible, which is not the
case.

With that:

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

> +		 * the drm_atomic_set_fence_for_plane() API to accept more than
> +		 * one. */
> +		dma_fence_get(fence);
> +		break;
> +	}
> +	dma_resv_iter_end(&cursor);
>  
> +	drm_atomic_set_fence_for_plane(state, fence);
>  	return 0;
>  }
>  EXPORT_SYMBOL_GPL(drm_gem_plane_helper_prepare_fb);
> -- 
> 2.25.1
> 

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