drm: make drm_atomic_set_mode_prop_for_crtc() more reliable

drm_atomic_set_mode_prop_for_crtc() does not clear the state->mode, so
old data may be left there when a new mode is set, possibly causing odd
issues.

This patch improves the situation by always clearing the state->mode
first.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: stable@vger.kernel.org
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
index 3ff1ed7b33db..c204ef32df16 100644
--- a/drivers/gpu/drm/drm_atomic.c
+++ b/drivers/gpu/drm/drm_atomic.c
@@ -351,6 +351,8 @@ int drm_atomic_set_mode_prop_for_crtc(struct drm_crtc_state *state,
         drm_property_unreference_blob(state->mode_blob);
         state->mode_blob = NULL;
 
+        memset(&state->mode, 0, sizeof(state->mode));
+
         if (blob) {
                 if (blob->length != sizeof(struct drm_mode_modeinfo) ||
                     drm_mode_convert_umode(&state->mode,
@@ -363,7 +365,6 @@ int drm_atomic_set_mode_prop_for_crtc(struct drm_crtc_state *state,
                 DRM_DEBUG_ATOMIC("Set [MODE:%s] for CRTC state %p\n",
                                  state->mode.name, state);
         } else {
-                memset(&state->mode, 0, sizeof(state->mode));
                 state->enable = false;
                 DRM_DEBUG_ATOMIC("Set [NOMODE] for CRTC state %p\n",
                                  state);