USB: Fallback to generic driver when specific driver fails

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>
Link: https://lore.kernel.org/r/20191016093933.693-6-hadess@hadess.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
index 9d1502a..f81606c 100644 (file)
--- a/drivers/usb/core/driver.c
+++ b/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 a/drivers/usb/core/generic.c b/drivers/usb/core/generic.c
index 84da85c..4626227 100644 (file)
--- a/drivers/usb/core/generic.c
+++ b/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 a/include/linux/usb.h b/include/linux/usb.h
index 3663bd7..ca1a5f1 100644 (file)
--- a/include/linux/usb.h
+++ b/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)