drm/amd/display: Add a new DC debug mask for PSR-SU

Some issues have been raised that appear to be tied to PSR-SU.
To allow users to confirm they're tied to PSR-SU without turning off
PSR entirely introduce a new debug mask:

amdgpu.dcdebugmask=0x200

Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -51,6 +51,9 @@ static bool link_supports_psrsu(struct dc_link *link)
 	    !link->dpcd_caps.psr_info.psr2_su_y_granularity_cap)
 		return false;
 
+	if (amdgpu_dc_debug_mask & DC_DISABLE_PSR_SU)
+		return false;
+
 	return dc_dmub_check_min_version(dc->ctx->dmub_srv->dmub);
 }
 

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

@@ -258,6 +258,7 @@ enum DC_DEBUG_MASK {
 	DC_DISABLE_REPLAY = 0x50,
 	DC_ENABLE_DPIA_TRACE = 0x80,
 	DC_ENABLE_DML2 = 0x100,
+	DC_DISABLE_PSR_SU = 0x200,
 };
 
 enum amd_dpm_forced_level;