usb: typec: ucsi: Determine common SVDM Version

This patch implements the following requirement in the Spec.

PD Spec Revision 3.0 Version 2.0 + ECNs 2020-12-10
6.4.4.2.3 Structured VDM Version
"The Structured VDM Version field of the Discover Identity Command
sent and received during VDM discovery Shall be used to determine the
lowest common Structured VDM Version supported by the Port Partners or
Cable Plug and Shall continue to operate using this Specification
Revision until they are Detached."

Acked-by: Heikki Krogerus <[e-mail]>
Signed-off-by: Kyle Tso <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/typec/ucsi/displayport.c

···
 {
 	struct ucsi_dp *dp = typec_altmode_get_drvdata(alt);
 	struct ucsi *ucsi = dp->con->ucsi;
+	int svdm_version;
 	u64 command;
 	u8 cur = 0;
 	int ret;
···
 	 * mode, and letting the alt mode driver continue.
 	 */
 
-	dp->header = VDO(USB_TYPEC_DP_SID, 1, SVDM_VER_1_0, CMD_ENTER_MODE);
+	svdm_version = typec_altmode_get_svdm_version(alt);
+	if (svdm_version < 0) {
+		ret = svdm_version;
+		goto err_unlock;
+	}
+
+	dp->header = VDO(USB_TYPEC_DP_SID, 1, svdm_version, CMD_ENTER_MODE);
 	dp->header |= VDO_OPOS(USB_TYPEC_DP_MODE);
 	dp->header |= VDO_CMDT(CMDT_RSP_ACK);
 
···
 static int ucsi_displayport_exit(struct typec_altmode *alt)
 {
 	struct ucsi_dp *dp = typec_altmode_get_drvdata(alt);
+	int svdm_version;
 	u64 command;
 	int ret = 0;
 
···
 	if (ret < 0)
 		goto out_unlock;
 
-	dp->header = VDO(USB_TYPEC_DP_SID, 1, SVDM_VER_1_0, CMD_EXIT_MODE);
+	svdm_version = typec_altmode_get_svdm_version(alt);
+	if (svdm_version < 0) {
+		ret = svdm_version;
+		goto out_unlock;
+	}
+
+	dp->header = VDO(USB_TYPEC_DP_SID, 1, svdm_version, CMD_EXIT_MODE);
 	dp->header |= VDO_OPOS(USB_TYPEC_DP_MODE);
 	dp->header |= VDO_CMDT(CMDT_RSP_ACK);
 
···
 	struct ucsi_dp *dp = typec_altmode_get_drvdata(alt);
 	int cmd_type = PD_VDO_CMDT(header);
 	int cmd = PD_VDO_CMD(header);
+	int svdm_version;
 
 	mutex_lock(&dp->con->lock);
 
···
 		return -EOPNOTSUPP;
 	}
 
+	svdm_version = typec_altmode_get_svdm_version(alt);
+	if (svdm_version < 0) {
+		mutex_unlock(&dp->con->lock);
+		return svdm_version;
+	}
+
 	switch (cmd_type) {
 	case CMDT_INIT:
-		dp->header = VDO(USB_TYPEC_DP_SID, 1, SVDM_VER_1_0, cmd);
+		if (PD_VDO_SVDM_VER(header) < svdm_version) {
+			typec_partner_set_svdm_version(dp->con->partner, PD_VDO_SVDM_VER(header));
+			svdm_version = PD_VDO_SVDM_VER(header);
+		}
+
+		dp->header = VDO(USB_TYPEC_DP_SID, 1, svdm_version, cmd);
 		dp->header |= VDO_OPOS(USB_TYPEC_DP_MODE);
 
 		switch (cmd) {

drivers/usb/typec/ucsi/ucsi.c

···
 
 	cap->revision = ucsi->cap.typec_version;
 	cap->pd_revision = ucsi->cap.pd_version;
+	cap->svdm_version = SVDM_VER_2_0;
 	cap->prefer_role = TYPEC_NO_PREFERRED_ROLE;
 
 	if (con->cap.op_mode & UCSI_CONCAP_OPMODE_AUDIO_ACCESSORY)