linux-kernel - Re: [PATCH v5 6/7] usb: typec: ucsi: Support mode selection to activate altmodes

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Message-ID: <aW-eqEYa8a1Y1aZb@kuha>
Date: Tue, 20 Jan 2026 17:26:32 +0200
From: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
To: Andrei Kuchynski <akuchynski@...omium.org>
Cc: Abhishek Pandit-Subedi <abhishekpandit@...omium.org>,
	Benson Leung <bleung@...omium.org>,
	Jameson Thies <jthies@...gle.com>, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org, chrome-platform@...ts.linux.dev,
	Tzung-Bi Shih <tzungbi@...nel.org>,
	Guenter Roeck <groeck@...omium.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>,
	Łukasz Bartosik <ukaszb@...omium.org>,
	Pooja Katiyar <pooja.katiyar@...el.com>,
	Johan Hovold <johan@...nel.org>,
	Hsin-Te Yuan <yuanhsinte@...omium.org>, Madhu M <madhu.m@...el.com>,
	Venkat Jayaraman <venkat.jayaraman@...el.com>
Subject: Re: [PATCH v5 6/7] usb: typec: ucsi: Support mode selection to
 activate altmodes

Mon, Jan 19, 2026 at 01:18:23PM +0000, Andrei Kuchynski kirjoitti:
> If the ucsi port driver supports modes selection, it should implement
> `add_partner_altmodes` and `remove_partner_altmodes` ucsi operations. With
> these operations the driver can manage the mode selection process.
> Once partner altmodes are registered, `add_partner_altmodes` is called to
> start the mode selection. When the partner is unregistered,
> `remove_partner_altmodes` is supposed to stop any ongoing processes and
> clean up the resources.
> 
> `typec_altmode_state_update` informes mode selection about the current mode
> of the Type-C connector.
> 
> Signed-off-by: Andrei Kuchynski <akuchynski@...omium.org>

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

> ---
> Changes in V5:
> - Use the no_mode_control field instead of
>   con->ucsi->cap.features & UCSI_CAP_ALT_MODE_OVERRIDE
> - Squash previous V4 patches 3/8 and 7/8 into a single patch
> 
>  drivers/usb/typec/ucsi/ucsi.c | 12 ++++++++++++
>  drivers/usb/typec/ucsi/ucsi.h |  4 ++++
>  2 files changed, 16 insertions(+)
> 
> diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c
> index a7b388dc7fa0f..251990475faa7 100644
> --- a/drivers/usb/typec/ucsi/ucsi.c
> +++ b/drivers/usb/typec/ucsi/ucsi.c
> @@ -314,6 +314,7 @@ void ucsi_altmode_update_active(struct ucsi_connector *con)
>  {
>  	const struct typec_altmode *altmode = NULL;
>  	u64 command;
> +	u16 svid = 0;
>  	int ret;
>  	u8 cur;
>  	int i;
> @@ -335,6 +336,10 @@ void ucsi_altmode_update_active(struct ucsi_connector *con)
>  	for (i = 0; con->partner_altmode[i]; i++)
>  		typec_altmode_update_active(con->partner_altmode[i],
>  					    con->partner_altmode[i] == altmode);
> +
> +	if (altmode)
> +		svid = altmode->svid;
> +	typec_altmode_state_update(con->partner, svid, 0);
>  }
>  
>  static int ucsi_altmode_next_mode(struct typec_altmode **alt, u16 svid)
> @@ -609,6 +614,8 @@ static int ucsi_register_altmodes(struct ucsi_connector *con, u8 recipient)
>  			desc.vdo = alt[j].mid;
>  			desc.svid = alt[j].svid;
>  			desc.roles = TYPEC_PORT_DRD;
> +			desc.mode_selection = con->ucsi->ops->add_partner_altmodes &&
> +					!con->typec_cap.no_mode_control;
>  
>  			ret = ucsi_register_altmode(con, &desc, recipient);
>  			if (ret)
> @@ -831,6 +838,8 @@ static int ucsi_check_altmodes(struct ucsi_connector *con)
>  	if (con->partner_altmode[0]) {
>  		num_partner_am = ucsi_get_num_altmode(con->partner_altmode);
>  		typec_partner_set_num_altmodes(con->partner, num_partner_am);
> +		if (con->ucsi->ops->add_partner_altmodes)
> +			con->ucsi->ops->add_partner_altmodes(con);
>  		ucsi_altmode_update_active(con);
>  		return 0;
>  	} else {
> @@ -1119,6 +1128,8 @@ static void ucsi_unregister_partner(struct ucsi_connector *con)
>  		return;
>  
>  	typec_set_mode(con->port, TYPEC_STATE_SAFE);
> +	if (con->ucsi->ops->remove_partner_altmodes)
> +		con->ucsi->ops->remove_partner_altmodes(con);
>  
>  	typec_partner_set_usb_power_delivery(con->partner, NULL);
>  	ucsi_unregister_partner_pdos(con);
> @@ -1659,6 +1670,7 @@ static int ucsi_register_port(struct ucsi *ucsi, struct ucsi_connector *con)
>  
>  	cap->driver_data = con;
>  	cap->ops = &ucsi_ops;
> +	cap->no_mode_control = !(con->ucsi->cap.features & UCSI_CAP_ALT_MODE_OVERRIDE);
>  
>  	if (ucsi->version >= UCSI_VERSION_2_0)
>  		con->typec_cap.orientation_aware = true;
> diff --git a/drivers/usb/typec/ucsi/ucsi.h b/drivers/usb/typec/ucsi/ucsi.h
> index 410389ef173ab..4797b4aa1e35b 100644
> --- a/drivers/usb/typec/ucsi/ucsi.h
> +++ b/drivers/usb/typec/ucsi/ucsi.h
> @@ -70,6 +70,8 @@ struct dentry;
>   * @update_altmodes: Squashes duplicate DP altmodes
>   * @update_connector: Update connector capabilities before registering
>   * @connector_status: Updates connector status, called holding connector lock
> + * @add_partner_altmodes: Start mode selection
> + * @remove_partner_altmodes: Clean mode selection
>   *
>   * Read and write routines for UCSI interface. @sync_write must wait for the
>   * Command Completion Event from the PPM before returning, and @async_write must
> @@ -88,6 +90,8 @@ struct ucsi_operations {
>  				struct ucsi_altmode *updated);
>  	void (*update_connector)(struct ucsi_connector *con);
>  	void (*connector_status)(struct ucsi_connector *con);
> +	void (*add_partner_altmodes)(struct ucsi_connector *con);
> +	void (*remove_partner_altmodes)(struct ucsi_connector *con);
>  };
>  
>  struct ucsi *ucsi_create(struct device *dev, const struct ucsi_operations *ops);
> -- 
> 2.52.0.457.g6b5491de43-goog

-- 
heikki