usb: typec: altmodes/displayport: Signal hpd low when exiting mode

Upon receiving an ACK for a sent EXIT_MODE message, the DisplayPort
driver currently resets the status and configuration of the port partner.
The hpd signal is not updated despite being part of the status, so the
Display stack can still transmit video despite typec_altmode_exit placing
the lanes in a Safe State.

Set hpd to low when a sent EXIT_MODE message is ACK'ed.

Fixes: 0e3bb7d6894d ("usb: typec: Add driver for DisplayPort alternate mode")
Cc: stable@vger.kernel.org
Signed-off-by: RD Babiera <rdbabiera@google.com>
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20231009210057.3773877-2-rdbabiera@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/typec/altmodes/displayport.c b/drivers/usb/typec/altmodes/displayport.c
index 426c88a516e5112b64d4aa7ebf03bd0757993333..59e0218a8bc56f4d37af2a325de35188edaa7ace 100644 (file)
--- a/drivers/usb/typec/altmodes/displayport.c
+++ b/drivers/usb/typec/altmodes/displayport.c
@@ -304,6 +304,11 @@ static int dp_altmode_vdm(struct typec_altmode *alt,
                        typec_altmode_update_active(alt, false);
                        dp->data.status = 0;
                        dp->data.conf = 0;
+                       if (dp->hpd) {
+                               drm_connector_oob_hotplug_event(dp->connector_fwnode);
+                               dp->hpd = false;
+                               sysfs_notify(&dp->alt->dev.kobj, "displayport", "hpd");
+                       }
                        break;
                case DP_CMD_STATUS_UPDATE:
                        dp->data.status = *vdo;