Re: [PATCH v4 2/5] drm/amd: fix fb references in async update

[Helen Koike]

On 6/3/19 1:56 PM, Helen Koike wrote:
> Async update callbacks are expected to set the old_fb in the new_state
> so prepare/cleanup framebuffers are balanced.
> 
> Calling drm_atomic_set_fb_for_plane() (which gets a reference of the new
> fb and put the old fb) is not required, as it's taken care by
> drm_mode_cursor_universal() when calling drm_atomic_helper_update_plane().
> 
> Suggested-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>
> Signed-off-by: Helen Koike <helen.koike@xxxxxxxxxxxxx>
> Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@xxxxxxx>

Cc: <stable@xxxxxxxxxxxxxxx> # v4.20+
Fixes: 674e78acae0d ("drm/amd/display: Add fast path for cursor plane
updates")


> 
> ---
> 
> Changes in v4: None
> Changes in v3: None
> Changes in v2:
> - added reviewed-by tag
> 
>  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> index 443b13ec268d..40624b2c630e 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -4347,8 +4347,7 @@ static void dm_plane_atomic_async_update(struct drm_plane *plane,
>  	struct drm_plane_state *old_state =
>  		drm_atomic_get_old_plane_state(new_state->state, plane);
>  
> -	if (plane->state->fb != new_state->fb)
> -		drm_atomic_set_fb_for_plane(plane->state, new_state->fb);
> +	swap(plane->state->fb, new_state->fb);
>  
>  	plane->state->src_x = new_state->src_x;
>  	plane->state->src_y = new_state->src_y;
>