drm/radeon: disable ss on DP for DCE3.x

Seems to cause problems with certain DP monitors.

Bug:
https://bugs.freedesktop.org/show_bug.cgi?id=40699

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

diff --git a/drivers/gpu/drm/radeon/atombios_crtc.c b/drivers/gpu/drm/radeon/atombios_crtc.c
index 0b9621c9aeea3b25da6bad8b121bfc3c3236ddcc..762b660af5aa0fe9584917cabcfd356d9da2c421 100644 (file)
--- a/drivers/gpu/drm/radeon/atombios_crtc.c
+++ b/drivers/gpu/drm/radeon/atombios_crtc.c
@@ -938,11 +938,14 @@ static bool atombios_crtc_prepare_pll(struct drm_crtc *crtc, struct drm_display_
                                                        radeon_atombios_get_ppll_ss_info(rdev,
                                                                                         &radeon_crtc->ss,
                                                                                         ATOM_DP_SS_ID1);
-                               } else
+                               } else {
                                        radeon_crtc->ss_enabled =
                                                radeon_atombios_get_ppll_ss_info(rdev,
                                                                                 &radeon_crtc->ss,
                                                                                 ATOM_DP_SS_ID1);
+                               }
+                               /* disable spread spectrum on DCE3 DP */
+                               radeon_crtc->ss_enabled = false;
                        }
                        break;
                case ATOM_ENCODER_MODE_LVDS: