[PATCH v3 5/6] USB: Fallback to generic driver when specific driver fails

[Bastien Nocera <hadess@hadess.net>]

If ->probe fails for a device specific driver, ask the driver core to
reprobe us, after having flagged the device for the generic driver to be
forced.

Signed-off-by: Bastien Nocera <hadess@hadess.net>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
---
 drivers/usb/core/driver.c  | 5 ++++-
 drivers/usb/core/generic.c | 3 +++
 include/linux/usb.h        | 1 +
 3 files changed, 8 insertions(+), 1 deletion(-)

diff --git drivers/usb/core/driver.c drivers/usb/core/driver.c
index 9d1502a9571d..f81606c6a35b 100644
--- drivers/usb/core/driver.c
+++ drivers/usb/core/driver.c
@@ -270,7 +270,10 @@ static int usb_probe_device(struct device *dev)
 		return error;
 
 	error = udriver->probe(udev);
-	/* TODO: fallback to generic driver in case of error */
+	if (error == -ENODEV && udriver != &usb_generic_driver) {
+		udev->use_generic_driver = 1;
+		return -EPROBE_DEFER;
+	}
 	return error;
 }
 
diff --git drivers/usb/core/generic.c drivers/usb/core/generic.c
index 84da85c13825..4626227a6dd2 100644
--- drivers/usb/core/generic.c
+++ drivers/usb/core/generic.c
@@ -213,6 +213,9 @@ static int __check_usb_generic(struct device_driver *drv, void *data)
 
 static bool usb_generic_driver_match(struct usb_device *udev)
 {
+	if (udev->use_generic_driver)
+		return true;
+
 	/*
 	 * If any other driver wants the device, leave the device to this other
 	 * driver.
diff --git include/linux/usb.h include/linux/usb.h
index 3663bd7b1fa4..ca1a5f1e1c5e 100644
--- include/linux/usb.h
+++ include/linux/usb.h
@@ -708,6 +708,7 @@ struct usb_device {
 	unsigned lpm_disable_count;
 
 	u16 hub_delay;
+	unsigned use_generic_driver:1;
 };
 #define	to_usb_device(d) container_of(d, struct usb_device, dev)
 
-- 
2.21.0