The patch below does not apply to the 4.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 603ba2dfb338b307aebe95fe344c479a59b3a175 Mon Sep 17 00:00:00 2001

From: Boris Brezillon boris.brezillon@bootlin.com Date: Tue, 24 Jul 2018 15:32:15 +0200 Subject: [PATCH] drm/atomic: Check old_plane_state->crtc in drm_atomic_helper_async_check()

Async plane update is supposed to work only when updating the FB or FB position of an already enabled plane. That does not apply to requests where the plane was previously disabled or assigned to a different CTRC.

Check old_plane_state->crtc value to make sure async plane update is allowed.

Fixes: fef9df8b5945 ("drm/atomic: initial support for asynchronous plane update") Cc: stable@vger.kernel.org Signed-off-by: Boris Brezillon boris.brezillon@bootlin.com Reviewed-by: Eric Anholt eric@anholt.net Link: https://patchwork.freedesktop.org/patch/msgid/20180724133215.31917-1-boris.b...

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c index 130da5195f3b..ff858b890045 100644 --- a/drivers/gpu/drm/drm_atomic_helper.c +++ b/drivers/gpu/drm/drm_atomic_helper.c @@ -1527,7 +1527,8 @@ int drm_atomic_helper_async_check(struct drm_device *dev, if (n_planes != 1) return -EINVAL;

- if (!new_plane_state->crtc) + if (!new_plane_state->crtc || + old_plane_state->crtc != new_plane_state->crtc) return -EINVAL;

funcs = plane->helper_private;