On Wed, 9 Oct 2019, Bastien Nocera wrote:
> Now that USB device drivers can reuse code from the generic USB device
> driver, we need to make sure that they get selected rather than the
> generic driver. Add an id_table and match vfunc to the usb_device_driver
> struct, which will get used to select a better matching driver at
> ->probe time.
>
> This is a similar mechanism to that used in the HID drivers, with the
> generic driver being selected unless there's a better matching one found
> in the registered drivers (see hid_generic_match() in
> drivers/hid/hid-generic.c).
>
> Signed-off-by: Bastien Nocera <had...@hadess.net>
> ---
> drivers/usb/core/driver.c | 15 +++++++++++++--
> drivers/usb/core/generic.c | 29 +++++++++++++++++++++++++++++
> include/linux/usb.h | 2 ++
> 3 files changed, 44 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
> index 50f92da8afcf..27ce63ed902d 100644
> --- a/drivers/usb/core/driver.c
> +++ b/drivers/usb/core/driver.c
> @@ -819,13 +819,24 @@ static int usb_device_match(struct device *dev, struct
> device_driver *drv)
> {
> /* devices and interfaces are handled separately */
> if (is_usb_device(dev)) {
> + struct usb_device *udev;
> + struct usb_device_driver *udrv;
>
> /* interface drivers never match devices */
> if (!is_usb_device_driver(drv))
> return 0;
>
> - /* TODO: Add real matching code */
> - return 1;
> + udev = to_usb_device(dev);
> + udrv = to_usb_device_driver(drv);
> +
> + if (udrv->id_table &&
> + usb_device_match_id(udev, udrv->id_table) != NULL) {
> + return 1;
> + }
> +
> + if (udrv->match)
> + return udrv->match(udev);
> + return 0;
What happens if the subclass driver's probe routine returns an error?
Don't you still want the device to be bound to the generic driver?
Alan Stern
