Re: [linux-pm] [patch/rft 2.6.17-rc2] swsusp resume must not device_suspend()

Nigel Cunningham
2006-04-24T22:31:58Z

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Hi David.

On Tuesday 25 April 2006 07:29, David Brownell wrote:
> I've noticed a bunch of problem reports that go like this:
>
> - boot system with some USB devices attached
> - echo disk > /sys/power/state
> - ... later resume ...
> - now those USB devices don't work right
> - unplug them/replug them, all is OK
>
> I recently observed this myself and tracked down one problem. The solution
> involves what kexec() does in much the same situation: before starting a
> new kernel, most hardware needs to be reset. Today, swsusp will suspend it
> instead, which is the root cause of the problem.

I'm not sure that it is. If we switched to not freezing devices, we'd then
cause issues with hardware such as hard drives. They need to know that we
just want things quiesced, mainly because we don't want to spin down drives.
It seems to me that the right solution might be for these usb devices to
treat a resume from a freeze as an indication that hardware should be reset.

Regards,

Nigel

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