[PATCH v2] usb: dwc3: Don't switch OTG -> peripheral if extcon is present

[Andrey Smirnov <andrew.smirnov@gmail.com>]

If the extcon device exists, get the mode from the extcon device. If
the controller is DRD and the driver is unable to determine the mode,
only then default the dr_mode to USB_DR_MODE_PERIPHERAL.

Cc: Felipe Balbi <balbi@kernel.org>
Cc: Thinh Nguyen <thinhn@synopsys.com>
Cc: linux-usb@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Reviewed-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
---

v1 of the patch:

https://lore.kernel.org/linux-usb/20220206014532.372109-1-andrew.smirnov@gmail.com/T/#u

previons discussion:

https://lore.kernel.org/linux-usb/20220131192102.4115473-1-andrew.smirnov@gmail.com/


 drivers/usb/dwc3/core.c | 56 ++++++++++++++++++++++++++++++++++++++++-
 drivers/usb/dwc3/drd.c  | 50 ------------------------------------
 2 files changed, 55 insertions(+), 51 deletions(-)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index f2448d0a9d39..09f283288ce7 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -23,6 +23,7 @@
 #include <linux/delay.h>
 #include <linux/dma-mapping.h>
 #include <linux/of.h>
+#include <linux/of_graph.h>
 #include <linux/acpi.h>
 #include <linux/pinctrl/consumer.h>
 #include <linux/reset.h>
@@ -84,7 +85,7 @@ static int dwc3_get_dr_mode(struct dwc3 *dwc)
 		 * mode. If the controller supports DRD but the dr_mode is not
 		 * specified or set to OTG, then set the mode to peripheral.
 		 */
-		if (mode == USB_DR_MODE_OTG &&
+		if (mode == USB_DR_MODE_OTG && !dwc->edev &&
 		    (!IS_ENABLED(CONFIG_USB_ROLE_SWITCH) ||
 		     !device_property_read_bool(dwc->dev, "usb-role-switch")) &&
 		    !DWC3_VER_IS_PRIOR(DWC3, 330A))
@@ -1462,6 +1463,51 @@ static void dwc3_check_params(struct dwc3 *dwc)
 	}
 }

+static struct extcon_dev *dwc3_get_extcon(struct dwc3 *dwc)
+{
+	struct device *dev = dwc->dev;
+	struct device_node *np_phy;
+	struct extcon_dev *edev = NULL;
+	const char *name;
+
+	if (device_property_read_bool(dev, "extcon"))
+		return extcon_get_edev_by_phandle(dev, 0);
+
+	/*
+	 * Device tree platforms should get extcon via phandle.
+	 * On ACPI platforms, we get the name from a device property.
+	 * This device property is for kernel internal use only and
+	 * is expected to be set by the glue code.
+	 */
+	if (device_property_read_string(dev, "linux,extcon-name", &name) == 0) {
+		edev = extcon_get_extcon_dev(name);
+		if (!edev)
+			return ERR_PTR(-EPROBE_DEFER);
+
+		return edev;
+	}
+
+	/*
+	 * Try to get an extcon device from the USB PHY controller's "port"
+	 * node. Check if it has the "port" node first, to avoid printing the
+	 * error message from underlying code, as it's a valid case: extcon
+	 * device (and "port" node) may be missing in case of "usb-role-switch"
+	 * or OTG mode.
+	 */
+	np_phy = of_parse_phandle(dev->of_node, "phys", 0);
+	if (of_graph_is_present(np_phy)) {
+		struct device_node *np_conn;
+
+		np_conn = of_graph_get_remote_node(np_phy, -1, -1);
+		if (np_conn)
+			edev = extcon_find_edev_by_node(np_conn);
+		of_node_put(np_conn);
+	}
+	of_node_put(np_phy);
+
+	return edev;
+}
+
 static int dwc3_probe(struct platform_device *pdev)
 {
 	struct device		*dev = &pdev->dev;
@@ -1561,6 +1607,14 @@ static int dwc3_probe(struct platform_device *pdev)
 		goto err2;
 	}

+	dwc->edev = dwc3_get_extcon(dwc);
+	if (IS_ERR(dwc->edev)) {
+		ret = PTR_ERR(dwc->edev);
+		dev_err_probe(dwc->dev, ret, "failed to get extcon");
+
+		goto err3;
+	}
+
 	ret = dwc3_get_dr_mode(dwc);
 	if (ret)
 		goto err3;
diff --git a/drivers/usb/dwc3/drd.c b/drivers/usb/dwc3/drd.c
index e2b68bb770d1..9a414edc439a 100644
--- a/drivers/usb/dwc3/drd.c
+++ b/drivers/usb/dwc3/drd.c
@@ -8,7 +8,6 @@
  */

 #include <linux/extcon.h>
-#include <linux/of_graph.h>
 #include <linux/platform_device.h>
 #include <linux/property.h>

@@ -438,51 +437,6 @@ static int dwc3_drd_notifier(struct notifier_block *nb,
 	return NOTIFY_DONE;
 }

-static struct extcon_dev *dwc3_get_extcon(struct dwc3 *dwc)
-{
-	struct device *dev = dwc->dev;
-	struct device_node *np_phy;
-	struct extcon_dev *edev = NULL;
-	const char *name;
-
-	if (device_property_read_bool(dev, "extcon"))
-		return extcon_get_edev_by_phandle(dev, 0);
-
-	/*
-	 * Device tree platforms should get extcon via phandle.
-	 * On ACPI platforms, we get the name from a device property.
-	 * This device property is for kernel internal use only and
-	 * is expected to be set by the glue code.
-	 */
-	if (device_property_read_string(dev, "linux,extcon-name", &name) == 0) {
-		edev = extcon_get_extcon_dev(name);
-		if (!edev)
-			return ERR_PTR(-EPROBE_DEFER);
-
-		return edev;
-	}
-
-	/*
-	 * Try to get an extcon device from the USB PHY controller's "port"
-	 * node. Check if it has the "port" node first, to avoid printing the
-	 * error message from underlying code, as it's a valid case: extcon
-	 * device (and "port" node) may be missing in case of "usb-role-switch"
-	 * or OTG mode.
-	 */
-	np_phy = of_parse_phandle(dev->of_node, "phys", 0);
-	if (of_graph_is_present(np_phy)) {
-		struct device_node *np_conn;
-
-		np_conn = of_graph_get_remote_node(np_phy, -1, -1);
-		if (np_conn)
-			edev = extcon_find_edev_by_node(np_conn);
-		of_node_put(np_conn);
-	}
-	of_node_put(np_phy);
-
-	return edev;
-}
-
 #if IS_ENABLED(CONFIG_USB_ROLE_SWITCH)
 #define ROLE_SWITCH 1
 static int dwc3_usb_role_switch_set(struct usb_role_switch *sw,
@@ -575,10 +529,6 @@ int dwc3_drd_init(struct dwc3 *dwc)
 {
 	int ret, irq;

-	dwc->edev = dwc3_get_extcon(dwc);
-	if (IS_ERR(dwc->edev))
-		return PTR_ERR(dwc->edev);
-
 	if (ROLE_SWITCH &&
 	    device_property_read_bool(dwc->dev, "usb-role-switch")) {
 		ret = dwc3_setup_role_switch(dwc);
--
2.25.1