linux-kernel - Re: [PATCH v1] usb: typec: altmodes/displayport: Signal hpd low when exiting mode

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Message-ID: <ZSUO0rkmTsRkV361@kuha.fi.intel.com>
Date:   Tue, 10 Oct 2023 11:44:02 +0300
From:   Heikki Krogerus <heikki.krogerus@...ux.intel.com>
To:     RD Babiera <rdbabiera@...gle.com>
Cc:     gregkh@...uxfoundation.org, badhri@...gle.com,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org
Subject: Re: [PATCH v1] usb: typec: altmodes/displayport: Signal hpd low when
 exiting mode

On Mon, Oct 09, 2023 at 09:00:58PM +0000, RD Babiera wrote:
> 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@...r.kernel.org
> Signed-off-by: RD Babiera <rdbabiera@...gle.com>

Acked-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>

> ---
>  drivers/usb/typec/altmodes/displayport.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/usb/typec/altmodes/displayport.c b/drivers/usb/typec/altmodes/displayport.c
> index f503cb4cd721..718da02036d8 100644
> --- a/drivers/usb/typec/altmodes/displayport.c
> +++ b/drivers/usb/typec/altmodes/displayport.c
> @@ -307,6 +307,11 @@ 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;
> 
> base-commit: 1053c4a4b8fcbd28386e80347e7c82d4d617e352
> -- 
> 2.42.0.609.gbb76f46606-goog

-- 
heikki