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 552b436..191218a 100644
--- a/drivers/gpu/drm/radeon/atombios_dp.c
+++ b/drivers/gpu/drm/radeon/atombios_dp.c
@@ -746,7 +746,8 @@
/* 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);