linux-kernel - [PATCH 5/8] usb: typec: ucsi: yoga-c630: fake AltModes for port 0

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Message-Id: <20250621-c630-ucsi-v1-5-a86de5e11361@oss.qualcomm.com>
Date: Sat, 21 Jun 2025 21:13:00 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Bryan O'Donoghue <bryan.odonoghue@...aro.org>,
        Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>
Cc: linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org
Subject: [PATCH 5/8] usb: typec: ucsi: yoga-c630: fake AltModes for port 0

EC firmware provides information about partner AltModes and handles the
DisplayPort AltMode internally, however it doesn't report AltModes of
the port to the host. Fake the DP AltMode for port0 in order to let
Linux bind displayport AltMode driver.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
---
 drivers/usb/typec/ucsi/ucsi.h           |  1 +
 drivers/usb/typec/ucsi/ucsi_yoga_c630.c | 22 ++++++++++++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/drivers/usb/typec/ucsi/ucsi.h b/drivers/usb/typec/ucsi/ucsi.h
index d02f6a3e2f50a4044eb3f22276931017cc624532..b711e1ecc3785eeb34e407e58df939f2d29bdb38 100644
--- a/drivers/usb/typec/ucsi/ucsi.h
+++ b/drivers/usb/typec/ucsi/ucsi.h
@@ -50,6 +50,7 @@ struct dentry;
 /* Command Status and Connector Change Indication (CCI) bits */
 #define UCSI_CCI_CONNECTOR(_c_)		(((_c_) & GENMASK(7, 1)) >> 1)
 #define UCSI_CCI_LENGTH(_c_)		(((_c_) & GENMASK(15, 8)) >> 8)
+#define UCSI_SET_CCI_LENGTH(_c_)	((_c_) << 8)
 #define UCSI_CCI_NOT_SUPPORTED		BIT(25)
 #define UCSI_CCI_CANCEL_COMPLETE	BIT(26)
 #define UCSI_CCI_RESET_COMPLETE		BIT(27)
diff --git a/drivers/usb/typec/ucsi/ucsi_yoga_c630.c b/drivers/usb/typec/ucsi/ucsi_yoga_c630.c
index 2005f64ebfe43ca2bcada2231ff99c578fdce877..506faf31b6e3a056e067f2bb69f5e9e5ea40e514 100644
--- a/drivers/usb/typec/ucsi/ucsi_yoga_c630.c
+++ b/drivers/usb/typec/ucsi/ucsi_yoga_c630.c
@@ -76,6 +76,28 @@ static int yoga_c630_ucsi_sync_control(struct ucsi *ucsi,
 				       u32 *cci,
 				       void *data, size_t size)
 {
+	int ret;
+
+	/*
+	 * EC doesn't return connector's DP mode even though it is supported.
+	 * Fake it.
+	 */
+	if (UCSI_COMMAND(command) == UCSI_GET_ALTERNATE_MODES &&
+	    UCSI_GET_ALTMODE_GET_CONNECTOR_NUMBER(command) == 1 &&
+	    UCSI_ALTMODE_RECIPIENT(command) == UCSI_RECIPIENT_CON &&
+	    UCSI_ALTMODE_OFFSET(command) == 0) {
+		static const struct ucsi_altmode alt = {
+			.svid = USB_TYPEC_DP_SID,
+			.mid = USB_TYPEC_DP_MODE,
+		};
+
+		dev_dbg(ucsi->dev, "faking DP altmode for con1\n");
+		memset(data, 0, size);
+		memcpy(data, &alt, min(sizeof(alt), size));
+		*cci = UCSI_CCI_COMMAND_COMPLETE | UCSI_SET_CCI_LENGTH(sizeof(alt));
+		return 0;
+	}
+
 	/*
 	 * EC can return AltModes present on CON1 (port0, right) for CON2
 	 * (port1, left) too. Ignore all requests going to CON2 (it doesn't

-- 
2.39.5