drm/radeon/dpm: implement vblank_too_short callback for si

Check if we can switch the mclk during the vblank time otherwise
we may get artifacts on the screen when the mclk changes.
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/radeon/ni_dpm.h

@@ -245,4 +245,6 @@ void ni_set_uvd_clock_after_set_eng_clock(struct radeon_device *rdev,
 					  struct radeon_ps *new_ps,
 					  struct radeon_ps *old_ps);
 
+bool ni_dpm_vblank_too_short(struct radeon_device *rdev);
+
 #endif

drivers/gpu/drm/radeon/radeon_asic.c

@@ -2294,6 +2294,7 @@ static struct radeon_asic si_asic = {
 		.print_power_state = &ni_dpm_print_power_state,
 		.debugfs_print_current_performance_level = &si_dpm_debugfs_print_current_performance_level,
 		.force_performance_level = &si_dpm_force_performance_level,
+		.vblank_too_short = &ni_dpm_vblank_too_short,
 	},
 	.pflip = {
 		.pre_page_flip = &evergreen_pre_page_flip,

drivers/gpu/drm/radeon/si_dpm.c

@@ -2906,7 +2906,8 @@ static void si_apply_state_adjust_rules(struct radeon_device *rdev,
 	u16 vddc, vddci;
 	int i;
 
-	if (rdev->pm.dpm.new_active_crtc_count > 1)
+	if ((rdev->pm.dpm.new_active_crtc_count > 1) ||
+	    ni_dpm_vblank_too_short(rdev))
 		disable_mclk_switching = true;
 	else
 		disable_mclk_switching = false;