drm/radeon/dp: sleep after powering up the display

According to the DP 1.1 spec, the sink must power
up within 1ms.  Noticed while reviewing Thierry's
drm/dp patches.

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/radeon/atombios_dp.c b/drivers/gpu/drm/radeon/atombios_dp.c
index 403ca00b8a5506a592412a581ea7eed15a2da324..4ad7643fce5fe9bdb8a479727400ae173475bb37 100644 (file)
--- a/drivers/gpu/drm/radeon/atombios_dp.c
+++ b/drivers/gpu/drm/radeon/atombios_dp.c
@@ -673,9 +673,11 @@ static int radeon_dp_link_train_init(struct radeon_dp_link_train_info *dp_info)
        u8 tmp;
 
        /* power up the sink */
-       if (dp_info->dpcd[0] >= 0x11)
+       if (dp_info->dpcd[0] >= 0x11) {
                radeon_write_dpcd_reg(dp_info->radeon_connector,
                                      DP_SET_POWER, DP_SET_POWER_D0);
+               usleep_range(1000, 2000);
+       }
 
        /* possibly enable downspread on the sink */
        if (dp_info->dpcd[3] & 0x1)