linux-kernel - [PATCH v1] usb: typec: tcpm: PD3.0 sinks can send Discover Identity even in device mode

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Date:   Wed, 17 Mar 2021 23:56:04 -0700
From:   Badhri Jagan Sridharan <badhri@...gle.com>
To:     Guenter Roeck <linux@...ck-us.net>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Badhri Jagan Sridharan <badhri@...gle.com>
Subject: [PATCH v1] usb: typec: tcpm: PD3.0 sinks can send Discover Identity
 even in device mode

>From 6.4.4.2 Structured VDM:
• Either Port May be an Initiator of Structured VDMs except for the Enter
Mode and Exit Mode Commands which Shall only be initiated by the DFP."

The above implies that when PD3.0 link is established PD3.0 sinks
can send out discover identity command/AMS once PD negotiation is done.
This allows discovering identity for PD3.0 UFP ports as well.

Signed-off-by: Badhri Jagan Sridharan <badhri@...gle.com>
---
 drivers/usb/typec/tcpm/tcpm.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
index 11d0c40bc47d..410856ec1702 100644
--- a/drivers/usb/typec/tcpm/tcpm.c
+++ b/drivers/usb/typec/tcpm/tcpm.c
@@ -3653,8 +3653,8 @@ static inline enum tcpm_state unattached_state(struct tcpm_port *port)
 
 static void tcpm_check_send_discover(struct tcpm_port *port)
 {
-	if (port->data_role == TYPEC_HOST && port->send_discover &&
-	    port->pd_capable)
+	if ((port->data_role == TYPEC_HOST || port->negotiated_rev > PD_REV20) &&
+	    port->send_discover && port->pd_capable)
 		tcpm_send_vdm(port, USB_SID_PD, CMD_DISCOVER_IDENT, NULL, 0);
 	port->send_discover = false;
 }
-- 
2.31.0.rc2.261.g7f71774620-goog