drm/amd/display: Limit max DSC target bpp for specific monitors

[Why]
Some monitors exhibit corruption at 16bpp DSC.

[How]
- Add helpers for patching edid caps.
- Use it for limiting DSC target bitrate to 15bpp for known monitors

Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Roman Li <Roman.Li@amd.com>
Cc: stable@vger.kernel.org
Tested-by: Daniel Wheeler <Daniel.Wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c

@@ -40,6 +40,39 @@
 
 #include "dm_helpers.h"
 
+struct monitor_patch_info {
+	unsigned int manufacturer_id;
+	unsigned int product_id;
+	void (*patch_func)(struct dc_edid_caps *edid_caps, unsigned int param);
+	unsigned int patch_param;
+};
+static void set_max_dsc_bpp_limit(struct dc_edid_caps *edid_caps, unsigned int param);
+
+static const struct monitor_patch_info monitor_patch_table[] = {
+{0x6D1E, 0x5BBF, set_max_dsc_bpp_limit, 15},
+{0x6D1E, 0x5B9A, set_max_dsc_bpp_limit, 15},
+};
+
+static void set_max_dsc_bpp_limit(struct dc_edid_caps *edid_caps, unsigned int param)
+{
+	if (edid_caps)
+		edid_caps->panel_patch.max_dsc_target_bpp_limit = param;
+}
+
+static int amdgpu_dm_patch_edid_caps(struct dc_edid_caps *edid_caps)
+{
+	int i, ret = 0;
+
+	for (i = 0; i < ARRAY_SIZE(monitor_patch_table); i++)
+		if ((edid_caps->manufacturer_id == monitor_patch_table[i].manufacturer_id)
+			&&  (edid_caps->product_id == monitor_patch_table[i].product_id)) {
+			monitor_patch_table[i].patch_func(edid_caps, monitor_patch_table[i].patch_param);
+			ret++;
+		}
+
+	return ret;
+}
+
 /* dm_helpers_parse_edid_caps
  *
  * Parse edid caps
@@ -125,6 +158,8 @@ enum dc_edid_status dm_helpers_parse_edid_caps(
 	kfree(sads);
 	kfree(sadb);
 
+	amdgpu_dm_patch_edid_caps(edid_caps);
+
 	return result;
 }