linux-kernel - [PATCH v2 6/8] platform/chrome: cros_ec_typec: Use Thunderbolt 3 cable discover mode VDO in USB4 mode

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Date:   Fri, 13 Nov 2020 12:25:01 -0800
From:   Utkarsh Patel <utkarsh.h.patel@...el.com>
To:     linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org
Cc:     heikki.krogerus@...ux.intel.com, pmalani@...omium.org,
        enric.balletbo@...labora.com, rajmohan.mani@...el.com,
        azhar.shaikh@...el.com, Utkarsh Patel <utkarsh.h.patel@...el.com>
Subject: [PATCH v2 6/8] platform/chrome: cros_ec_typec: Use Thunderbolt 3 cable discover mode VDO in USB4 mode

Configure Thunderbolt3/USB4 cable generation value by filing Thunderbolt 3
cable discover mode VDO to support rounded and non-rounded Thunderbolt3/
USB4 cables.
While we are here use Thunderbolt 3 cable discover mode VDO to fill active
cable plug link training value.

Suggested-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Signed-off-by: Utkarsh Patel <utkarsh.h.patel@...el.com>

--
Changes in v2:
- No change.
--
---
 drivers/platform/chrome/cros_ec_typec.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/platform/chrome/cros_ec_typec.c b/drivers/platform/chrome/cros_ec_typec.c
index 8111ed1fc574..b7416e82c3b3 100644
--- a/drivers/platform/chrome/cros_ec_typec.c
+++ b/drivers/platform/chrome/cros_ec_typec.c
@@ -514,8 +514,18 @@ static int cros_typec_enable_usb4(struct cros_typec_data *typec,
 	else if (pd_ctrl->control_flags & USB_PD_CTRL_ACTIVE_CABLE)
 		data.eudo |= EUDO_CABLE_TYPE_RE_TIMER << EUDO_CABLE_TYPE_SHIFT;
 
-	data.active_link_training = !!(pd_ctrl->control_flags &
-				       USB_PD_CTRL_ACTIVE_LINK_UNIDIR);
+	/*
+	 * This driver does not have access to the identity information or
+	 * capabilities of the cable, so we don't know is it a real USB4 or
+	 * TBT3 cable. Therefore pretending that it's always TBT3 cable by
+	 * filling the TBT3 Cable VDO.
+	 */
+	data.tbt_cable_vdo = TBT_MODE;
+
+	if (pd_ctrl->control_flags & USB_PD_CTRL_ACTIVE_LINK_UNIDIR)
+		data.tbt_cable_vdo |= TBT_CABLE_LINK_TRAINING;
+
+	data.tbt_cable_vdo |= TBT_SET_CABLE_ROUNDED(pd_ctrl->cable_gen);
 
 	port->state.alt = NULL;
 	port->state.data = &data;
-- 
2.17.1