[PATCH 3/4] drm/radeon/dpm/rs780: don't enable sclk scaling if not required

[Alex Deucher]

If the low and high sclks are the same, there is no need to
enable sclk scaling.  This causes display stability issues on
certain boards.

Fixes:
https://bugzilla.kernel.org/show_bug.cgi?id=60857

Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
Cc: stable at vger.kernel.org
---
 drivers/gpu/drm/radeon/rs780_dpm.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/radeon/rs780_dpm.c b/drivers/gpu/drm/radeon/rs780_dpm.c
index 31487ce..eb336bf 100644
--- a/drivers/gpu/drm/radeon/rs780_dpm.c
+++ b/drivers/gpu/drm/radeon/rs780_dpm.c
@@ -499,6 +499,9 @@ static void rs780_activate_engine_clk_scaling(struct radeon_device *rdev,
 	    (new_state->sclk_low == old_state->sclk_low))
 		return;
 
+	if (new_state->sclk_high == new_state->sclk_low)
+		return;
+
 	rs780_clk_scaling_enable(rdev, true);
 }
 
-- 
1.8.3.1