On Fri, Jul 24, 2020 at 01:32:40PM +0300, Andy Shevchenko wrote:
> On Fri, Jul 24, 2020 at 12:03 PM Bastien Nocera <hadess@xxxxxxxxxx> 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.
>
> ...
>
> > +static int __usb_bus_reprobe_drivers(struct device *dev, void *data)
> > +{
> > + struct usb_device_driver *new_udriver = data;
> > + struct usb_device_driver *udriver;
> > + struct usb_device *udev;
> > +
> > + if (!dev->driver)
> > + return 0;
> > +
> > + udriver = to_usb_device_driver(dev->driver);
> > + if (udriver != &usb_generic_driver)
> > + return 0;
>
> What about
>
> static bool is_dev_usb_generic_driver(dev)
> {
> struct usb_device_driver *udd = dev->driver ?
> to_usb_device_driver(dev->driver) : NULL;
>
> return udd == &usb_generic_driver;
> }
>
> if (!is_dev_usb_generic_driver)
> return 0;
>
> ?
Why would you want to add more lines of code to do the same thing?
Abstraction is fine up to point, but excessive abstraction only makes
things more difficult.
>
> > + udev = to_usb_device(dev);
> > + if (usb_device_match_id(udev, new_udriver->id_table) != NULL ||
> > + (new_udriver->match && new_udriver->match(udev) == 0))
> > + device_reprobe(dev);
> > +
> > + return 0;
>
> What about
>
> udev = to_usb_device(dev);
> if (usb_device_match_id(udev, new_udriver->id_table) == NULL)
> return 0;
> ?
The logic is wrong. If usb_device_match_id() returns NULL then we want
to go ahead with the second test, not give up right away. But this
could be written as:
if (usb_device_match_id(udev, new_udriver->id_table) == NULL &&
(!new_udriver->match || new_udriver->match(udev) != 0))
return 0;
device_reprobe(dev);
This would make the overall flow of the routine more uniform.
> > + /* Check whether any device could be better served with
> > + * this new driver
> > + */
>
> Comment style?
Right:
/*
* Multiline comments
* should look like this.
*/
> ...
>
> > + if (new_udriver->match || new_udriver->id_table)
>
> But match check is incorporated in the loop function.
Agreed, this test is redundant. However, we should test that
new_udriver != &usb_generic_driver.
Alan Stern
>
> > + bus_for_each_dev(&usb_bus_type, NULL, new_udriver,
> > + __usb_bus_reprobe_drivers);
>
> --
> With Best Regards,
> Andy Shevchenko
