drm/bridge: tc358767: disable only video stream in tc_stream_disable

Currently the code writes 0 to DP0CTL in tc_stream_disable(), which
disables the whole DP link instead of just the video stream. We always
disable the link and the stream together from tc_bridge_disable(), so
this doesn't cause any issues.

Nevertheless, fix this by only clearing VID_EN in tc_stream_disable to
stop the video stream while keeping the link enabled.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190528082747.3631-12-tomi.valkeinen@ti.com

drivers/gpu/drm/bridge/tc358767.c

@@ -1076,10 +1076,13 @@ static int tc_stream_enable(struct tc_data *tc)
 static int tc_stream_disable(struct tc_data *tc)
 {
 	int ret;
+	u32 val;
 
 	dev_dbg(tc->dev, "disable video stream\n");
 
-	tc_write(DP0CTL, 0);
+	tc_read(DP0CTL, &val);
+	val &= ~VID_EN;
+	tc_write(DP0CTL, val);
 
 	tc_pxl_pll_dis(tc);