linux-kernel - [PATCH v4 7/8] usb: typec: ucsi: Support mode selection to activate altmodes

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Message-ID: <20260113130536.3068311-8-akuchynski@chromium.org>
Date: Tue, 13 Jan 2026 13:05:35 +0000
From: Andrei Kuchynski <akuchynski@...omium.org>
To: Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
	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
Cc: 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>,
	Abel Vesa <abel.vesa@...aro.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>,
	Andrei Kuchynski <akuchynski@...omium.org>
Subject: [PATCH v4 7/8] usb: typec: ucsi: Support mode selection to activate altmodes

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>
---
 drivers/usb/typec/ucsi/ucsi.c | 11 +++++++++++
 drivers/usb/typec/ucsi/ucsi.h |  4 ++++
 2 files changed, 15 insertions(+)

diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c
index deb210c066cb5..4a6e23b55b10c 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->ucsi->cap.features & UCSI_CAP_ALT_MODE_OVERRIDE;
 
 			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);
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