The patch below does not apply to the 5.6-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 14ed1c908a7a623cc0cbf0203f8201d1b7d31d16 Mon Sep 17 00:00:00 2001

From: Harry Wentland harry.wentland@amd.com Date: Thu, 28 May 2020 09:44:44 -0400 Subject: [PATCH] Revert "drm/amd/display: disable dcn20 abm feature for bring up"

This reverts commit 96cb7cf13d8530099c256c053648ad576588c387.

This change was used for DCN2 bringup and is no longer desired. In fact it breaks backlight on DCN2 systems.

Cc: Alexander Monakov amonakov@ispras.ru Cc: Hersen Wu hersenxs.wu@amd.com Cc: Anthony Koo Anthony.Koo@amd.com Cc: Michael Chiu Michael.Chiu@amd.com Signed-off-by: Harry Wentland harry.wentland@amd.com Acked-by: Alex Deucher alexander.deucher@amd.com Reviewed-by: Nicholas Kazlauskas nicholas.kazlauskas@amd.com Reported-and-tested-by: Alexander Monakov amonakov@ispras.ru Signed-off-by: Alex Deucher alexander.deucher@amd.com Cc: stable@vger.kernel.org

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c index d53c60b37cc6..f42e7e67ddba 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c @@ -1356,7 +1356,7 @@ static int dm_late_init(void *handle) unsigned int linear_lut[16]; int i; struct dmcu *dmcu = NULL; - bool ret = false; + bool ret;

if (!adev->dm.fw_dmcu) return detect_mst_link_for_all_connectors(adev->ddev); @@ -1377,13 +1377,10 @@ static int dm_late_init(void *handle) */ params.min_abm_backlight = 0x28F;

- /* todo will enable for navi10 */ - if (adev->asic_type <= CHIP_RAVEN) { - ret = dmcu_load_iram(dmcu, params); + ret = dmcu_load_iram(dmcu, params);

- if (!ret) - return -EINVAL; - } + if (!ret) + return -EINVAL;

return detect_mst_link_for_all_connectors(adev->ddev); }