From aa54e2ee80b4f653f75b9139ae7500ee8cd5ad5f Mon Sep 17 00:00:00 2001 From: "Jasper St. Pierre" Date: Thu, 20 Nov 2014 19:59:15 -0800 Subject: [PATCH] drm/atomic_helper: Cope with plane->crtc == NULL in disable helper The drm core can call the plane disable hook multiple times, which means it can get called when plane->crtc is already NULL. That in turn means we can't get at the implicit acquire ctx we use in the atomic helpers for legacy entries points. We could try to pass drm_modeset_legacy_acquire_ctx a drm_device pointer so that it can cope with a NULL crtc. But that still doesn't work since the cursor ioctls (remapped with the universal cursor plane support code) only grabs the crtc locks. So the global acquire context isn't set eitehr. The real solution here would be to bite the bullet and wire up explicit acquire context parameters to all relevant functions. We need to do that anyway (to be able to get rid of some small allocations which we can't cope with failing). But that's a lot of work and better done once atomic has settled a bit. So meanwhile just catch this case in the helper and bail out. Signed-off-by: Jasper St. Pierre Reviewed-by: Rob Clark Cc: Daniel Vetter [danvet: Completely rewrite commit message and comment but keep Jasper's logic and author credits since his patch is the only short-term solution that works.] Tested-by: Thierry Reding Signed-off-by: Daniel Vetter --- drivers/gpu/drm/drm_atomic_helper.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c index 4368581ac1eb..d981d07d50cd 100644 --- a/drivers/gpu/drm/drm_atomic_helper.c +++ b/drivers/gpu/drm/drm_atomic_helper.c @@ -1275,6 +1275,17 @@ int drm_atomic_helper_disable_plane(struct drm_plane *plane) struct drm_plane_state *plane_state; int ret = 0; + /* + * FIXME: Without plane->crtc set we can't get at the implicit legacy + * acquire context. The real fix will be to wire the acquire ctx through + * everywhere we need it, but meanwhile prevent chaos by just skipping + * this noop. The critical case is the cursor ioctls which a) only grab + * crtc/cursor-plane locks (so we need the crtc to get at the right + * acquire context) and b) can try to disable the plane multiple times. + */ + if (!plane->crtc) + return 0; + state = drm_atomic_state_alloc(plane->dev); if (!state) return -ENOMEM; -- 2.20.1