Re: [PATCH 1/2] usb: linux/usb.h: Move USB port definition to usb.h

Kai-Heng Feng
2024-09-06T02:20:54Z

On Thu, Sep 5, 2024 at 2:50 PM Greg KH <gregkh@linuxfoundation.org> wrote:
>
> On Thu, Sep 05, 2024 at 02:24:31PM +0800, Kai-Heng Feng wrote:
> > On Thu, Sep 5, 2024 at 1:20 PM Greg KH <gregkh@linuxfoundation.org> wrote:
> > >
> > > On Thu, Sep 05, 2024 at 12:24:46PM +0800, Kai-Heng Feng wrote:
> > > > Move struct usb_port to linux/usb.h so other subsystems can use it too.
> > >
> > > These really are "internal to the usb core" functions and variables, I
> > > am loath to export them as it requires that you "know" what the device
> > > type is of something without any recorse if you get it wrong. I
> > > commented on patch 2/2 about that.
> > >
> > > Could we provide a usb core function for you instead to help out? What
> > > exactly are you trying to get access to on the USB bus that you need to
> > > use here, the port or the device?
> >
> > The device so the quirk can check its vendor and product id.
> >
> > That means a function or helper that can return USB port/device from
> > an ACPI path.
>
> So you don't want the port, only the device. Why not just search the
> bus for a device, you don't care where in the acpi path it lives, right?
> Or better yet, do this in the driver for the device itself, that's when
> you know you have the right device.

The crucial part of the quirk is the device links between VGA and USB
controller to enforce suspend order, it can be hard to create and
maintain the links when the USB device can disappear at any moment.

Kai-Heng

>
> thanks,
>
> greg k-h