drm/amd: Add debug mask for subviewport mclk switch

[Why&How]
Expose a new dc debug mask enum to force a subviewport memory clock switch
to facilitate easy testing.
Signed-off-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -1560,6 +1560,9 @@ static int amdgpu_dm_init(struct amdgpu_device *adev)
 	if (amdgpu_dc_debug_mask & DC_DISABLE_CLOCK_GATING)
 		adev->dm.dc->debug.disable_clock_gate = true;
 
+	if (amdgpu_dc_debug_mask & DC_FORCE_SUBVP_MCLK_SWITCH)
+		adev->dm.dc->debug.force_subvp_mclk_switch = true;
+
 	r = dm_dmub_hw_init(adev);
 	if (r) {
 		DRM_ERROR("DMUB interface failed to initialize: status=%d\n", r);

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

@@ -248,6 +248,7 @@ enum DC_DEBUG_MASK {
 	DC_DISABLE_DSC = 0x4,
 	DC_DISABLE_CLOCK_GATING = 0x8,
 	DC_DISABLE_PSR = 0x10,
+	DC_FORCE_SUBVP_MCLK_SWITCH = 0x20,
 };
 
 enum amd_dpm_forced_level;