[Intel-gfx] [PATCH] drm/i915/display: refine eDP power off sequence

[Lee Shawn C]

The current eDP disable sequence like this.

disable plane > disable backlight (include T9, the delay
from backlight disable to end of valid video data) >
disalbe transcoder/pipe > disable eDP power

Found abnormal pixel output after plane off sometimes.
It did not cause any issue but impact user experience.
So we modify the eDP disable flow to turn backlight off
earlier to avoid abnormal display.

disable backlight > disable plane > disalbe transcoder/pipe
> disable eDP power

Cc: Shankar Uma <uma.shankar at intel.com>
Cc: Jani Nikula <jani.nikula at linux.intel.com>
Signed-off-by: Lee Shawn C <shawn.c.lee at intel.com>
---
 drivers/gpu/drm/i915/display/intel_display.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index 72e2091d9fcb..d08927036350 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -2045,10 +2045,8 @@ static void hsw_crtc_disable(struct intel_atomic_state *state,
 	 * FIXME collapse everything to one hook.
 	 * Need care with mst->ddi interactions.
 	 */
-	if (!intel_crtc_is_bigjoiner_slave(old_crtc_state)) {
-		intel_encoders_disable(state, crtc);
+	if (!intel_crtc_is_bigjoiner_slave(old_crtc_state))
 		intel_encoders_post_disable(state, crtc);
-	}
 }
 
 static void i9xx_pfit_enable(const struct intel_crtc_state *crtc_state)
@@ -7224,6 +7222,10 @@ static void intel_commit_modeset_disables(struct intel_atomic_state *state)
 			continue;
 
 		intel_pre_plane_update(state, crtc);
+
+		if (!intel_crtc_is_bigjoiner_slave(old_crtc_state))
+			intel_encoders_disable(state, crtc);
+
 		intel_crtc_disable_planes(state, crtc);
 	}
 
-- 
2.31.1