drm/radeon/kms: properly set the CLK_REF bit for DCE3 devices

If the ss clock is external, the CLK_REF bit needs to be set
in the SetPixelClock parameters.  This should fix DP failures
in the channel equalization loop.

Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@gmail.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/gpu/drm/radeon/atombios_crtc.c b/drivers/gpu/drm/radeon/atombios_crtc.c
index dab06fb17cb2..f5819ba481d9 100644
--- a/drivers/gpu/drm/radeon/atombios_crtc.c
+++ b/drivers/gpu/drm/radeon/atombios_crtc.c
@@ -815,6 +815,8 @@ static void atombios_crtc_program_pll(struct drm_crtc *crtc,
                         args.v3.ucPostDiv = post_div;
                         args.v3.ucPpll = pll_id;
                         args.v3.ucMiscInfo = (pll_id << 2);
+                        if (ss_enabled && (ss->type & ATOM_EXTERNAL_SS_MASK))
+                                args.v3.ucMiscInfo |= PIXEL_CLOCK_MISC_REF_DIV_SRC;
                         args.v3.ucTransmitterId = encoder_id;
                         args.v3.ucEncoderMode = encoder_mode;
                         break;