[PATCH v5] drm/vc4: fix fb references in async update

[Helen Koike]

On 6/10/19 10:18 AM, Helen Koike wrote:
> commit c16b85559dcfb5a348cc085a7b4c75ed49b05e2c upstream.
> 
> 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().
> 
> Cc: <stable at vger.kernel.org> # v4.19+
> Fixes: 539c320bfa97 ("drm/vc4: update cursors asynchronously through atomic")
> Suggested-by: Boris Brezillon <boris.brezillon at collabora.com>
> Signed-off-by: Helen Koike <helen.koike at collabora.com>
> Reviewed-by: Boris Brezillon <boris.brezillon at collabora.com>
> Signed-off-by: Boris Brezillon <boris.brezillon at collabora.com>
> Link: https://patchwork.freedesktop.org/patch/msgid/20190603165610.24614-5-helen.koike@collabora.com
> ---
> 
> Hi,
> 
> This patch failed to apply on kernel stable v4.19, I'm re-sending it
> fixing the conflict.

fyi, this patch was already applied in other stable branches.

Thanks
Helen

> 
> Thanks
> Helen
> 
>  drivers/gpu/drm/vc4/vc4_plane.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/gpu/drm/vc4/vc4_plane.c b/drivers/gpu/drm/vc4/vc4_plane.c
> index ab39315c9078..39e608271263 100644
> --- a/drivers/gpu/drm/vc4/vc4_plane.c
> +++ b/drivers/gpu/drm/vc4/vc4_plane.c
> @@ -818,6 +818,7 @@ static void vc4_plane_atomic_async_update(struct drm_plane *plane,
>  		drm_atomic_set_fb_for_plane(plane->state, state->fb);
>  	}
>  
> +	swap(plane->state->fb, state->fb);
>  	/* Set the cursor's position on the screen.  This is the
>  	 * expected change from the drm_mode_cursor_universal()
>  	 * helper.
>