[PATCH v2 5/6] USB: Fallback to generic driver when specific driver fails

[Bastien Nocera]

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 <had...@hadess.net>
---
 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 a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
index e86065f3be7f..6190986c7d99 100644
--- 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 84da85c13825..4626227a6dd2 100644
--- 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 a3f0142b816a..669579b37e54 100644
--- 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)
 
-- 
2.21.0