drm/radeon/dpm: implement vblank_too_short callback for 7xx

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>

1 files changed, 11 insertions, 0 deletions

diff --git a/drivers/gpu/drm/radeon/rv770_dpm.c b/drivers/gpu/drm/radeon/rv770_dpm.c
index 4de50c811879..d914e04ea39a 100644
--- a/drivers/gpu/drm/radeon/rv770_dpm.c
+++ b/drivers/gpu/drm/radeon/rv770_dpm.c
@@ -2508,3 +2508,14 @@ u32 rv770_dpm_get_mclk(struct radeon_device *rdev, bool low)
 	else
 		return requested_state->high.mclk;
 }
+
+bool rv770_dpm_vblank_too_short(struct radeon_device *rdev)
+{
+	u32 vblank_time = r600_dpm_get_vblank_time(rdev);
+
+	if (vblank_time < 300)
+		return true;
+	else
+		return false;
+
+}