drm/radeon: disable mclk switching with 120hz+ monitors

These tend to be problematic even if the vblank period is
long enough.  This needs more investigation across a wider
range of displays.  Disable for now.

bugs:
https://bugs.freedesktop.org/show_bug.cgi?id=87796
https://bugs.freedesktop.org/show_bug.cgi?id=89198

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

diff --git a/drivers/gpu/drm/radeon/radeon_pm.c b/drivers/gpu/drm/radeon/radeon_pm.c
index 9f758d39420dd4affddb42116a09e695a17b6abe..33cf4108386dbba4ef70a0e372eb992d1ff7e4d3 100644 (file)
--- a/drivers/gpu/drm/radeon/radeon_pm.c
+++ b/drivers/gpu/drm/radeon/radeon_pm.c
@@ -852,6 +852,12 @@ static struct radeon_ps *radeon_dpm_pick_power_state(struct radeon_device *rdev,
                        single_display = false;
        }
 
+       /* 120hz tends to be problematic even if they are under the
+        * vblank limit.
+        */
+       if (single_display && (r600_dpm_get_vrefresh(rdev) >= 120))
+               single_display = false;
+
        /* certain older asics have a separare 3D performance state,
         * so try that first if the user selected performance
         */