drm/radeon: dp only enable enhanced framing if sink supports.

DisplayPort spec v1.1a, Table 2-52.

Same commit to Intel by ajax in 9962c9252e46eda7058067cbe73bdf1ed74b0d37

Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

diff --git a/drivers/gpu/drm/radeon/atombios_dp.c b/drivers/gpu/drm/radeon/atombios_dp.c
index 552b436451fd49d54df3edb412a63734debad250..191218ad92e7906925337f83e8c7f85125c47b91 100644 (file)
--- a/drivers/gpu/drm/radeon/atombios_dp.c
+++ b/drivers/gpu/drm/radeon/atombios_dp.c
@@ -746,7 +746,8 @@ static int radeon_dp_link_train_init(struct radeon_dp_link_train_info *dp_info)
 
        /* set the lane count on the sink */
        tmp = dp_info->dp_lane_count;
-       if (dp_info->dpcd[0] >= 0x11)
+       if (dp_info->dpcd[DP_DPCD_REV] >= 0x11 &&
+           dp_info->dpcd[DP_MAX_LANE_COUNT] & DP_ENHANCED_FRAME_CAP)
                tmp |= DP_LANE_COUNT_ENHANCED_FRAME_EN;
        radeon_write_dpcd_reg(dp_info->radeon_connector, DP_LANE_COUNT_SET, tmp);