[PATCH v2] drm/mgag200: Fix gamma lut not initialized.

[Jocelyn Falempe]

When mgag200 switched from simple KMS to regular atomic helpers,
the initialization of the gamma settings was lost.
This leads to a black screen, if the bios/uefi doesn't use the same
pixel color depth.

v2: rebase on top of drm-misc-fixes, and add Cc stable tag.

Link: https://bugzilla.redhat.com/show_bug.cgi?id=2171155
Fixes: 1baf9127c482 ("drm/mgag200: Replace simple-KMS with regular atomic helpers")
Cc: <stable at vger.kernel.org>
Tested-by: Phil Oester <kernel at linuxace.com>
Reviewed-by: Thomas Zimmermann <tzimmermann at suse.de>
Signed-off-by: Jocelyn Falempe <jfalempe at redhat.com>
---
 drivers/gpu/drm/mgag200/mgag200_mode.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c b/drivers/gpu/drm/mgag200/mgag200_mode.c
index 0a5aaf78172a..576c4c838a33 100644
--- a/drivers/gpu/drm/mgag200/mgag200_mode.c
+++ b/drivers/gpu/drm/mgag200/mgag200_mode.c
@@ -640,6 +640,11 @@ void mgag200_crtc_helper_atomic_enable(struct drm_crtc *crtc, struct drm_atomic_
 	if (funcs->pixpllc_atomic_update)
 		funcs->pixpllc_atomic_update(crtc, old_state);
 
+	if (crtc_state->gamma_lut)
+		mgag200_crtc_set_gamma(mdev, format, crtc_state->gamma_lut->data);
+	else
+		mgag200_crtc_set_gamma_linear(mdev, format);
+
 	mgag200_enable_display(mdev);
 
 	if (funcs->enable_vidrst)

base-commit: a26cc2934331b57b5a7164bff344f0a2ec245fc0
-- 
2.39.2