On Thu, 2020-07-23 at 02:19 +0000, Peter Chen wrote:
> On 20-07-22 17:53:25, Bastien Nocera wrote:
> > 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.
> >
>
> What do you mean "reprobe" for your device? Do you mean the
> mfi_fc_probe
> is not called? If it is, Would you please check why usb_device_match
> at drivers/usb/core/driver.c does not return true for your device?
mfi_fc_probe() isn't called because the device already has the generic
driver attached by the time the apple-mfi-fastcharge driver is loaded.
