4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Andrey Gusakov <andrey.gusa...@cogentembedded.com>


[ Upstream commit cffd2b16c01c3431a7a7dd62e722af33490fc436 ]

Do not fail data rates higher than 2.7 and more than 2 lanes.
Try to fall back to 2.7Gbps and 2 lanes.

Acked-by: Philipp Zabel <p.za...@pengutronix.de>
Reviewed-by: Andrzej Hajda <a.ha...@samsung.com>
Signed-off-by: Andrey Gusakov <andrey.gusa...@cogentembedded.com>
Signed-off-by: Andrzej Hajda <a.ha...@samsung.com>
Link: 
https://patchwork.freedesktop.org/patch/msgid/1510073785-16108-2-git-send-email-andrey.gusa...@cogentembedded.com
Signed-off-by: Sasha Levin <alexander.le...@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 drivers/gpu/drm/bridge/tc358767.c |   14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

--- a/drivers/gpu/drm/bridge/tc358767.c
+++ b/drivers/gpu/drm/bridge/tc358767.c
@@ -603,8 +603,15 @@ static int tc_get_display_props(struct t
        ret = drm_dp_link_probe(&tc->aux, &tc->link.base);
        if (ret < 0)
                goto err_dpcd_read;
-       if ((tc->link.base.rate != 162000) && (tc->link.base.rate != 270000))
-               goto err_dpcd_inval;
+       if (tc->link.base.rate != 162000 && tc->link.base.rate != 270000) {
+               dev_dbg(tc->dev, "Falling to 2.7 Gbps rate\n");
+               tc->link.base.rate = 270000;
+       }
+
+       if (tc->link.base.num_lanes > 2) {
+               dev_dbg(tc->dev, "Falling to 2 lanes\n");
+               tc->link.base.num_lanes = 2;
+       }
 
        ret = drm_dp_dpcd_readb(&tc->aux, DP_MAX_DOWNSPREAD, tmp);
        if (ret < 0)
@@ -637,9 +644,6 @@ static int tc_get_display_props(struct t
 err_dpcd_read:
        dev_err(tc->dev, "failed to read DPCD: %d\n", ret);
        return ret;
-err_dpcd_inval:
-       dev_err(tc->dev, "invalid DPCD\n");
-       return -EINVAL;
 }
 
 static int tc_set_video_mode(struct tc_data *tc, struct drm_display_mode *mode)


Reply via email to