Add gamma set function to correct brightness values.
It applies arbitrary mapping curve to compensate the
incorrect transfer function of the panel.

Signed-off-by: Bibby Hsieh <redacted>
---
 drivers/gpu/drm/mediatek/mtk_drm_crtc.c     |    8 ++++++-
 drivers/gpu/drm/mediatek/mtk_drm_crtc.h     |    1 +
 drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c |   31 +++++++++++++++++++++++++++
 drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.h |   10 +++++++++
 4 files changed, 49 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
index 24aa3ba..cbb460a5 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
+++ b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c

@@ -409,6 +409,9 @@ static void mtk_drm_crtc_atomic_flush(struct drm_crtc *crtc,
 	}
 	if (pending_planes)
 		mtk_crtc->pending_planes = true;
+	if (crtc->state->color_mgmt_changed)
+		for (i = 0; i < mtk_crtc->ddp_comp_nr; i++)
+			mtk_ddp_gamma_set(mtk_crtc->ddp_comp[i], crtc->state);
 }
 
 static const struct drm_crtc_funcs mtk_crtc_funcs = {

@@ -418,6 +421,7 @@ static const struct drm_crtc_funcs mtk_crtc_funcs = {
 	.reset			= mtk_drm_crtc_reset,
 	.atomic_duplicate_state	= mtk_drm_crtc_duplicate_state,
 	.atomic_destroy_state	= mtk_drm_crtc_destroy_state,
+	.gamma_set		= drm_atomic_helper_legacy_gamma_set,
 };
 
 static const struct drm_crtc_helper_funcs mtk_crtc_helper_funcs = {

@@ -568,7 +572,9 @@ int mtk_drm_crtc_create(struct drm_device *drm_dev,
 				&mtk_crtc->planes[1].base, pipe);
 	if (ret < 0)
 		goto unprepare;
-
+	drm_mode_crtc_set_gamma_size(&mtk_crtc->base, MTK_LUT_SIZE);
+	drm_helper_crtc_enable_color_mgmt(&mtk_crtc->base, MTK_LUT_SIZE,
+					  MTK_LUT_SIZE);