drm/radeon/dpm: implement vblank_too_short callback for btc

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, 15 insertions, 1 deletions

diff --git a/drivers/gpu/drm/radeon/btc_dpm.c b/drivers/gpu/drm/radeon/btc_dpm.c
index 91567448c55d..0bfd55e08820 100644
--- a/drivers/gpu/drm/radeon/btc_dpm.c
+++ b/drivers/gpu/drm/radeon/btc_dpm.c
@@ -2059,6 +2059,19 @@ static void btc_init_stutter_mode(struct radeon_device *rdev)
 	}
 }
 
+bool btc_dpm_vblank_too_short(struct radeon_device *rdev)
+{
+	struct rv7xx_power_info *pi = rv770_get_pi(rdev);
+	u32 vblank_time = r600_dpm_get_vblank_time(rdev);
+	u32 switch_limit = pi->mem_gddr5 ? 450 : 100;
+
+	if (vblank_time < switch_limit)
+		return true;
+	else
+		return false;
+
+}
+
 static void btc_apply_state_adjust_rules(struct radeon_device *rdev,
 					 struct radeon_ps *rps)
 {
@@ -2068,7 +2081,8 @@ static void btc_apply_state_adjust_rules(struct radeon_device *rdev,
 	u32 mclk, sclk;
 	u16 vddc, vddci;
 
-	if (rdev->pm.dpm.new_active_crtc_count > 1)
+	if ((rdev->pm.dpm.new_active_crtc_count > 1) ||
+	    btc_dpm_vblank_too_short(rdev))
 		disable_mclk_switching = true;
 	else
 		disable_mclk_switching = false;