drm/amd: Add debug option to disable subvp

Some monitors flicker when subvp is enabled which maybe related to
an uncommon timing they use. To isolate such issues, add a debug
option to help isolate this the issue for debugging.

Signed-off-by: Aurabindo Pillai <[email protected]>
Acked-by: Alex Deucher <[email protected]>
Suggested-by: Alex Deucher <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>

Author: Aurabindo Pillai

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

@@ -2034,6 +2034,9 @@ static int amdgpu_dm_init(struct amdgpu_device *adev)
 	if (amdgpu_dc_debug_mask & DC_FORCE_SUBVP_MCLK_SWITCH)
 		adev->dm.dc->debug.force_subvp_mclk_switch = true;
 
+	if (amdgpu_dc_debug_mask & DC_DISABLE_SUBVP)
+		adev->dm.dc->debug.force_disable_subvp = true;
+
 	if (amdgpu_dc_debug_mask & DC_ENABLE_DML2) {
 		adev->dm.dc->debug.using_dml2 = true;
 		adev->dm.dc->debug.using_dml21 = true;

drivers/gpu/drm/amd/include/amd_shared.h

@@ -349,6 +349,11 @@ enum DC_DEBUG_MASK {
 	 * @DC_DISABLE_HDMI_CEC: If set, disable HDMI-CEC feature in amdgpu driver.
 	 */
 	DC_DISABLE_HDMI_CEC = 0x10000,
+
+	/*
+	 * @DC_DISABLE_SUBVP: If set, disable DCN Sub-Viewport feature in amdgpu driver.
+	 */
+	DC_DISABLE_SUBVP = 0x20000,
 };
 
 enum amd_dpm_forced_level;