There are two paths into intel_cleanup_plane_fb, the normal completion path and the failure path.
In the failure case, intel_cleanup_plane_fb is called before drm_atomic_helper_swap_state, so any wait_req reference made in intel_prepare_plane_fb will be in old_intel_state->wait_req.
In the normal completion path, drm_atomic_helper_swap_state has already been called, so the plane state holding the just-used wait_req will not be in old_intel_state->wait_req, rather it will be in the state associated with the plane itself.
Clearing this reference ensures that the wait_req will be freed as soon as it the related mode setting operation is complete, rather than waiting for some future mode setting operation to eventually dereference it.
The existing dereference of old_intel_state->wait_req is still required as that will hold the wait_req when the mode setting operation fails.
cc: Daniel Vetter daniel.vetter@intel.com cc: David Airlie airlied@linux.ie cc: intel-gfx@lists.freedesktop.org cc: dri-devel@lists.freedesktop.org Signed-off-by: Keith Packard keithp@keithp.com --- drivers/gpu/drm/i915/intel_display.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c index 3074c56..dbabaf3 100644 --- a/drivers/gpu/drm/i915/intel_display.c +++ b/drivers/gpu/drm/i915/intel_display.c @@ -13924,6 +13924,7 @@ intel_cleanup_plane_fb(struct drm_plane *plane, struct drm_device *dev = plane->dev; struct intel_plane *intel_plane = to_intel_plane(plane); struct intel_plane_state *old_intel_state; + struct intel_plane_state *intel_state = to_intel_plane_state(plane->state); struct drm_i915_gem_object *old_obj = intel_fb_obj(old_state->fb); struct drm_i915_gem_object *obj = intel_fb_obj(plane->state->fb);
@@ -13941,6 +13942,7 @@ intel_cleanup_plane_fb(struct drm_plane *plane, (obj && !(obj->frontbuffer_bits & intel_plane->frontbuffer_bit))) i915_gem_track_fb(old_obj, obj, intel_plane->frontbuffer_bit);
+ i915_gem_request_assign(&intel_state->wait_req, NULL); i915_gem_request_assign(&old_intel_state->wait_req, NULL); }