Re: [PATCH] USB: core: Use device_driver directly in struct usb_driver and usb_device_driver

[Yajun Deng <yajun.deng@linux.dev>]

On 2023/12/15 20:40, Greg KH wrote:
> On Fri, Dec 15, 2023 at 02:31:01PM +0800, Yajun Deng wrote:
>> There is usbdrv_wrap in struct usb_driver and usb_device_driver,
>> it contains device_driver and for_devices. for_devices is used to
>> distinguish between device drivers and interface drivers.
> Yes.
>
>> We can compare that if 'drv->probe' is equal to usb_probe_device instead
>> of using for_devices in is_usb_device_driver().
> Why?


For remove struct usbdrv_wrap. As we can see,  other structs use 
device_driver directly.

struct sdio_driver {

... ...

         struct device_driver drv;
};


struct pcie_port_service_driver {

... ...

         struct device_driver driver;
};

and so on ...

So there is no need a wrapper for device_driver if we can implement 
is_usb_device_driver().

>
>> Remove struct usbdrv_wrap, use device_driver directly in struct usb_driver
>> and usb_device_driver. This makes the code more concise.
> Really?  What does this help out with?  Are there future changes that
> require this?


No, just for cleanups and consistency with other structs.

> I'm all for cleanups, but I don't see what this helps with.
>
> Also, you have a coding style issue in this patch, which means I
> couldn't take it anyway:
>
>> +extern int usb_probe_device(struct device *dev);
> We don't do that in .c files :(


It's in drivers/usb/core/usb.h, not in .c files.

>
> thanks,
>
> greg k-h