drm/radeon/dpm/rs780: don't enable sclk scaling if not required

commit e40210cca98068835acd5a4fe760bf96b3a1aa48 upstream.

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@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpu/drm/radeon/rs780_dpm.c b/drivers/gpu/drm/radeon/rs780_dpm.c
index 0f858b85af7ca2fbb991f8fb3d10b20ea7648361..429672335678e52a498dc7737cae5c5ae18a9043 100644 (file)
--- a/drivers/gpu/drm/radeon/rs780_dpm.c
+++ b/drivers/gpu/drm/radeon/rs780_dpm.c
@@ -486,6 +486,9 @@ 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);
 }