Re: [RFC PATCH] usb/acpi: Add support usb port power off mechanism for device fixed on the motherboard

Sarah Sharp
2012-05-11T20:11:31Z

On Fri, May 11, 2012 at 11:35:43AM -0700, Greg KH wrote:
> On Fri, May 11, 2012 at 01:44:26PM -0400, Alan Stern wrote:
> > On Sat, 12 May 2012, Lan Tianyu wrote:
> > > So I should work on the external ports without devices firstly and
> > > add the sys file for user to control?
> >
> > Yes, I think so. It will be less controversial and probably simpler.
> > When that mechanism is ready, you should be able to use it
> > automatically for unconnectable ports.
> >
> > One tricky thing: In theory, there should be a separate sysfs file for
> > each port. That seems like a lot of overhead though; is there any way
> > to present the information in a single file that won't offend sysfs
> > purists?
>
> Why is that a lot of "overhead"? It's what, 7-9 files max? As Sarah
> points out, one file for all ports is racy and can get to be a mess.
>
> But then again, I'm a "sysfs purist" :)

Theoretically there's no maximum number for xHCI root ports, so I
wouldn't be so sure you'll only have 9 files on future xHCI hosts.

Sarah Sharp