[PATCH] drm/atomic: Fix the early return in drm_atomic_set_mode_for_crtc()

[Ville Syrjala]

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

The early return in drm_atomic_set_mode_for_crtc() isn't quite
right. It would mistakenly return and fail to update
crtc_state->enable if someone actually tried to set a zeroed
mode on a currently disabled crtc. I suppose that should never
happen but better safe than sorry.

Additionally the early return will not be taken if we're trying to
disable an already disable crtc. While that is not actually harmful
it is inconsistent, so let's handle that case as well.

Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 drivers/gpu/drm/drm_atomic_uapi.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_atomic_uapi.c b/drivers/gpu/drm/drm_atomic_uapi.c
index 86ac33922b09..ed0ea82e8a1d 100644
--- a/drivers/gpu/drm/drm_atomic_uapi.c
+++ b/drivers/gpu/drm/drm_atomic_uapi.c
@@ -68,8 +68,13 @@ int drm_atomic_set_mode_for_crtc(struct drm_crtc_state *state,
 	struct drm_mode_modeinfo umode;
 
 	/* Early return for no change. */
-	if (mode && memcmp(&state->mode, mode, sizeof(*mode)) == 0)
-		return 0;
+	if (state->enable) {
+		if (mode && memcmp(&state->mode, mode, sizeof(*mode)) == 0)
+			return 0;
+	} else {
+		if (!mode)
+			return 0;
+	}
 
 	drm_property_blob_put(state->mode_blob);
 	state->mode_blob = NULL;
-- 
2.18.1