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

Commit Message

Bastien Nocera Oct. 15, 2019, 2:28 p.m. UTC

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 <[e-mail]>
---
 drivers/usb/core/driver.c  | 5 ++++-
 drivers/usb/core/generic.c | 3 +++
 include/linux/usb.h        | 1 +
 3 files changed, 8 insertions(+), 1 deletion(-)

Patch

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)