[PATCH] drm/atomic: only run atomic_check() if crtc is active

[Gustavo Padovan]

From: Gustavo Padovan <gustavo.padovan at collabora.co.uk>

Fixes an regression added by 3ae2436 (drm/exynos/mixer: replace
direct cross-driver call with drm mode) and while this regression was
caused by a change in the exynos driver it makes sense to add the
check on atomic core to benefit other drivers as well.

The whole atomic update fails if the exynos hdmi display is not
present/active.  Add a test to only run atomic_check() if the CRTC is
active.

Signed-off-by: Gustavo Padovan <gustavo.padovan at collabora.co.uk>
---
 drivers/gpu/drm/drm_atomic_helper.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index 0c6f621..7e3cb48 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -510,6 +510,9 @@ drm_atomic_helper_check_planes(struct drm_device *dev,
 	for_each_crtc_in_state(state, crtc, crtc_state, i) {
 		const struct drm_crtc_helper_funcs *funcs;
 
+		if (!crtc_state->active)
+			continue;
+
 		funcs = crtc->helper_private;
 
 		if (!funcs || !funcs->atomic_check)
-- 
2.1.0