On Wed, 2020-07-22 at 11:26 -0400, Alan Stern wrote:
> On Wed, Jul 22, 2020 at 11:46:27AM +0200, Bastien Nocera wrote:
> > When a new device with a specialised device driver is plugged in,
> > the
> > new driver will be modprobe()'d but the driver core will attach the
> > "generic" driver to the device.
> >
> > After that, nothing will trigger a reprobe when the modprobe()'d
> > device
> > driver has finished initialising, as the device has the "generic"
> > driver attached to it.
> >
> > Trigger a reprobe ourselves when new specialised drivers get
> > registered.
> >
> > Signed-off-by: Bastien Nocera <hadess@xxxxxxxxxx>
> > ---
> > drivers/usb/core/driver.c | 31 +++++++++++++++++++++++++++++--
> > 1 file changed, 29 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
> > index f81606c6a35b..a6187dd2186c 100644
> > --- a/drivers/usb/core/driver.c
> > +++ b/drivers/usb/core/driver.c
> > @@ -905,6 +905,30 @@ static int usb_uevent(struct device *dev,
> > struct kobj_uevent_env *env)
> > return 0;
> > }
> >
> > +static int __usb_bus_reprobe_drivers(struct device *dev, void
> > *data)
> > +{
> > + struct usb_device_driver *udriver = to_usb_device_driver(dev-
> > >driver);
> > + struct usb_device *udev = to_usb_device(dev);
> > +
> > + if (udriver == &usb_generic_driver &&
> > + !udev->use_generic_driver)
> > + return device_reprobe(dev);
> > +
> > + return 0;
> > +}
> > +
> > +static int __usb_device_driver_added(struct device_driver *drv,
> > void *data)
> > +{
> > + struct usb_device_driver *udrv = to_usb_device_driver(drv);
> > +
> > + if (udrv->match) {
> > + bus_for_each_dev(&usb_bus_type, NULL, udrv,
> > + __usb_bus_reprobe_drivers);
>
> What does udrv get used for here?
>
> > + }
> > +
> > + return 0;
> > +}
> > +
> > /**
> > * usb_register_device_driver - register a USB device (not
> > interface) driver
> > * @new_udriver: USB operations for the device driver
> > @@ -934,13 +958,16 @@ int usb_register_device_driver(struct
> > usb_device_driver *new_udriver,
> >
> > retval = driver_register(&new_udriver->drvwrap.driver);
> >
> > - if (!retval)
> > + if (!retval) {
> > + bus_for_each_drv(&usb_bus_type, NULL, NULL,
> > + __usb_device_driver_added);
>
> This looks funny. You're calling both bus_for_each_drv() and
> bus_for_each_dev(). Can't you skip this iterator and just call
> bus_for_each_dev() directly?
You're right, looks like this could be simplified somewhat. I'm
building and testing a smaller patch.
Thanks
