Patches for fixing "black screen" issue on MBP with AMD GPU on Linux >=4.18

0-README.md

README

The following patches are fixing the "black screen" problem starting with Linux 4.18.

I have adapted the patches for Linux 4.19.

Refs

• Dunedan/mbp-2016-linux#73 (comment)
• Dunedan/mbp-2016-linux#73 (comment)
• https://bugs.freedesktop.org/show_bug.cgi?id=108693
• https://patchwork.freedesktop.org/series/52164/

1-2-drm-amdgpu-Add-max_bpc-connector-property.patch

diff -Nur linux-4.19.2.orig/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c linux-4.19.2/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
--- linux-4.19.2.orig/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c	2018-11-13 20:09:00.000000000 +0100
+++ linux-4.19.2/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c	2018-11-20 11:49:40.834148553 +0100
@@ -626,6 +626,11 @@
 					 "dither",
 					 amdgpu_dither_enum_list, sz);
 
+	adev->mode_info.max_bpc_property =
+		drm_property_create_range(adev->ddev, 0, "max_bpc", 8, 16);
+	if (!adev->mode_info.max_bpc_property)
+		return -ENOMEM;
+
 	return 0;
 }
 
diff -Nur linux-4.19.2.orig/drivers/gpu/drm/amd/amdgpu/amdgpu_mode.h linux-4.19.2/drivers/gpu/drm/amd/amdgpu/amdgpu_mode.h
--- linux-4.19.2.orig/drivers/gpu/drm/amd/amdgpu/amdgpu_mode.h	2018-11-13 20:09:00.000000000 +0100
+++ linux-4.19.2/drivers/gpu/drm/amd/amdgpu/amdgpu_mode.h	2018-11-20 11:50:33.299062353 +0100
@@ -339,6 +339,8 @@
 	struct drm_property *audio_property;
 	/* FMT dithering */
 	struct drm_property *dither_property;
+	/* maximum number of bits per channel for monitor color */
+	struct drm_property *max_bpc_property;
 	/* hardcoded DFP edid from BIOS */
 	struct edid *bios_hardcoded_edid;
 	int bios_hardcoded_edid_size;

2-2-drm-amd-display-Support-max_bpc-connector-property.patch

diff -Nur linux-4.19.2.orig/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c linux-4.19.2/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
--- linux-4.19.2.orig/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c	2018-11-13 20:09:00.000000000 +0100
+++ linux-4.19.2/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c	2018-11-20 11:59:38.655483130 +0100
@@ -2213,8 +2213,14 @@
 static enum dc_color_depth
 convert_color_depth_from_display_info(const struct drm_connector *connector)
 {
+	struct dm_connector_state *dm_conn_state =
+		to_dm_connector_state(connector->state);
 	uint32_t bpc = connector->display_info.bpc;
 
+	if (dm_conn_state && bpc > dm_conn_state->max_bpc)
+		/* Round down to nearest even number. */
+		bpc = dm_conn_state->max_bpc - (dm_conn_state->max_bpc & 1);
+
 	switch (bpc) {
 	case 0:
 		/* Temporary Work around, DRM don't parse color depth for
@@ -2796,6 +2802,9 @@
 	} else if (property == adev->mode_info.underscan_property) {
 		dm_new_state->underscan_enable = val;
 		ret = 0;
+	} else if (property == adev->mode_info.max_bpc_property) {
+		dm_new_state->max_bpc = val;
+		ret = 0;
 	}
 
 	return ret;
@@ -2838,6 +2847,9 @@
 	} else if (property == adev->mode_info.underscan_property) {
 		*val = dm_state->underscan_enable;
 		ret = 0;
+	} else if (property == adev->mode_info.max_bpc_property) {
+		*val = dm_state->max_bpc;
+		ret = 0;
 	}
 	return ret;
 }
@@ -3658,6 +3670,9 @@
 	drm_object_attach_property(&aconnector->base.base,
 				adev->mode_info.underscan_vborder_property,
 				0);
+	drm_object_attach_property(&aconnector->base.base,
+				adev->mode_info.max_bpc_property,
+				0);
 
 }
 
diff -Nur linux-4.19.2.orig/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h linux-4.19.2/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
--- linux-4.19.2.orig/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h	2018-11-13 20:09:00.000000000 +0100
+++ linux-4.19.2/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h	2018-11-20 11:56:09.625271867 +0100
@@ -215,6 +215,7 @@
 	enum amdgpu_rmx_type scaling;
 	uint8_t underscan_vborder;
 	uint8_t underscan_hborder;
+	uint8_t max_bpc;
 	bool underscan_enable;
 	struct mod_freesync_user_enable user_enable;
 	bool freesync_capable;