Re: [RFC PATCH 00/13] firmware loader: introduce cache/uncache firmware

[Oliver Neukum <oneukum@suse.de>]

On Wednesday 25 July 2012 20:35:28 Ming Lei wrote:
> CC usb guys and list
> 
> On Wed, Jul 25, 2012 at 1:53 AM, Linus Torvalds
> <torvalds@linux-foundation.org> wrote:
> >
> > I really think the isight thing is a totally different thing entirely.
> >
> > And quite frankly, that's just a BUG in the USB implementation. If the
> > USB ID changes, it shouldn't be considered a "resume" thing at all,
> > but a probe thing, and that should not be done in early resume - it
> > should be done *after* the resume is done.
> 
> IMO, usbcore may have found the ID changes during resume(reset_resume),
> and make the device disconnect. The disconnect event will be handled
> in hubd kthread, which is woken up before usermodehelper_enable()(see
> thaw_processes), so request_firmware will return failure during probe()
> inside hubd kthread.
> 
> The cache firmware patch set may not help the situation, because the
> original isight usb device for downloading firmware has been disconnected
> before system suspend, so firmware loader can't cache the firmware for
> the device.
> 
> The below patch should fix the problem above.

This is likely unwise. You'd better introduce a special flag for kernel threads
that should be thawed only after user space will have been thawed.

	Regards
		Oliver