The patch below does not apply to the 4.16-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From d78fd7255881645fc645e23145d469385227170d Mon Sep 17 00:00:00 2001

From: Harry Wentland harry.wentland@amd.com Date: Thu, 12 Apr 2018 16:37:09 -0400 Subject: [PATCH] drm/amd/display: Don't program bypass on linear regamma LUT

Even though this is required for degamma since DCE HW only supports a couple predefined LUTs we can just program the LUT directly for regamma.

This fixes dark screens which occurs when we program regamma to bypass while degamma is using srgb LUT.

Signed-off-by: Harry Wentland harry.wentland@amd.com Reviewed-by: Leo Li sunpeng.li@amd.com Cc: stable@vger.kernel.org Signed-off-by: Alex Deucher alexander.deucher@amd.com

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c index f6cb502c303f..25f064c01038 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c @@ -138,13 +138,6 @@ int amdgpu_dm_set_regamma_lut(struct dm_crtc_state *crtc) lut = (struct drm_color_lut *)blob->data; lut_size = blob->length / sizeof(struct drm_color_lut);

- if (__is_lut_linear(lut, lut_size)) { - /* Set to bypass if lut is set to linear */ - stream->out_transfer_func->type = TF_TYPE_BYPASS; - stream->out_transfer_func->tf = TRANSFER_FUNCTION_LINEAR; - return 0; - } - gamma = dc_create_gamma(); if (!gamma) return -ENOMEM;