FAILED: patch "[PATCH] drm/amd/display: disable dcn20 abm feature for bring up" failed to apply to 5.6-stable tree

[<gregkh@linuxfoundation.org>]

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 96cb7cf13d8530099c256c053648ad576588c387 Mon Sep 17 00:00:00 2001
From: hersen wu <hersenxs.wu@amd.com>
Date: Thu, 28 Feb 2019 16:35:24 -0500
Subject: [PATCH] drm/amd/display: disable dcn20 abm feature for bring up

[WHY] dcn20 enable usb-c dp ALT mode in dmcu. There is bug
when enable abm feature which cause system crash. dal team
will debug this bug later.

[HOW] disable dcn abm feature for dcn20.

Signed-off-by: hersen wu <hersenxs.wu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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 5971aef4f033..72d14f680932 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -781,7 +781,7 @@ static int dm_late_init(void *handle)
 	unsigned int linear_lut[16];
 	int i;
 	struct dmcu *dmcu = adev->dm.dc->res_pool->dmcu;
-	bool ret;
+	bool ret = false;
 
 	for (i = 0; i < 16; i++)
 		linear_lut[i] = 0xFFFF * i / 15;
@@ -792,10 +792,13 @@ static int dm_late_init(void *handle)
 	params.backlight_lut_array_size = 16;
 	params.backlight_lut_array = linear_lut;
 
-	ret = dmcu_load_iram(dmcu, params);
+	/* todo will enable for navi10 */
+	if (adev->asic_type <= CHIP_RAVEN) {
+		ret = dmcu_load_iram(dmcu, params);
 
-	if (!ret)
-		return -EINVAL;
+		if (!ret)
+			return -EINVAL;
+	}
 
 	return detect_mst_link_for_all_connectors(adev->ddev);
 }