drm/mgag200: Fix gamma lut not initialized.

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@vger.kernel.org>
Tested-by: Phil Oester <kernel@linuxace.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Jocelyn Falempe <jfalempe@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230510131034.284078-1-jfalempe@redhat.com

diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c b/drivers/gpu/drm/mgag200/mgag200_mode.c
index 0a5aaf78172a6784742ad0ef9e5bed4427cadd6c..576c4c838a331a2432cdba80349ab32c04082836 100644 (file)
--- 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)