Re: Re: Hotplug events during sleep transition

[Pavel Machek <pavel@suse.cz>]

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Hi!

> At this point I'm starting to feel like the proverbial 
> "man-in-the-middle".  Recently I submitted a patch adding

Rock and a hard place?

> suspend/resume 
> support to the usblp driver.  Greg objected to it because it added 
> explicit checks for whether the driver was suspended before starting up 
> I/O operations.  He said that such checks did not belong in USB drivers, 
> they belonged in the USB core.  (You can read his original comments in
> 
> http://marc.theaimsgroup.com/?l=linux-usb-devel&m=113418897301873&w=2
> 
> .)  So now what should we do?
> 
> 	Require userspace to rmmod usblp before suspending?

No.

> 	Add suspend and resume methods to usblp, but make it so they
> 	only cancel outstanding I/O, while relying on usbcore to fail
> 	any new I/O requests?

It is not *that* bad, actually. In system suspend/resume cases, no new
I/O requests can happen, because userspace is frozen. Because of
runtime suspend, you should handle I/O errors properly, but you should
handle I/O errors properly, anyway, so... looks like a solution to me.

> Neither of those feels good to me.  The only other options I can think of 
> are:
> 
> 	Unbind usblp in lieu of suspending it.

If this can be done in reasonable ammount of not-too-ugly code, why
not? I think that even Patrick can be convinced by nice patch.

> 	Make usblp check whether it is suspended before submitting any
> 	I/O requests.

Ugly.

								Pavel
-- 
Thanks, Sharp!

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