[PATCH] drm/bridge: adv7511: Reset registers on hotplug

[Sean Paul]

The bridge loses its hw state when the cable is unplugged. If we detect
this case in the hpd handler, reset its state.

Reported-by: Rob Clark <robdclark at gmail.com>
Signed-off-by: Sean Paul <seanpaul at chromium.org>
---
This is the follow-up to "drm/msm: Disable mdp5 crtc when there are no
active planes". I incorrectly assumed the modeset was required from the
msm side, but Rob pointed out that he thought it might be a bridge
issue.

 drivers/gpu/drm/bridge/adv7511/adv7511_drv.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
index 73021b388e12..dd3ff2f2cdce 100644
--- a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
+++ b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
@@ -429,6 +429,18 @@ static void adv7511_hpd_work(struct work_struct *work)
 	else
 		status = connector_status_disconnected;
 
+	/*
+	 * The bridge resets its registers on unplug. So when we get a plug
+	 * event and we're already supposed to be powered, cycle the bridge to
+	 * restore its state.
+	 */
+	if (status == connector_status_connected &&
+	    adv7511->connector.status == connector_status_disconnected &&
+	    adv7511->powered) {
+		regcache_mark_dirty(adv7511->regmap);
+		adv7511_power_on(adv7511);
+	}
+
 	if (adv7511->connector.status != status) {
 		adv7511->connector.status = status;
 		if (status == connector_status_disconnected)
-- 
Sean Paul, Software Engineer, Google / Chromium OS