Re: suspend.c vs driver-model.txt

[Benjamin Herrenschmidt <benh-XVmvHMARGAS8U2dJNN8I7kB+6BGkLq7r@public.gmane.org>]

>
>There's power cycle and whole kernel bootup. Device state is
>completely lost during suspend to disk.

As it is during suspend-to-ram in most cases (most devices except
a couple of them are actually powered down and the drivers have to
bring them back up, at least on pmac, though on x86, the APM BIOS
helps you a bit there).

So basically, drivers are responsible to bring back the device
in whatever state it was at the save_state step of the suspend,
in the same way for but suspend to disk and to RAM. What I want to
make sure is that the driver-side semantics remain the same for
swsusp and suspend-to-RAM.
That includes the fact that save state will actually block IOs, and
that is necessary to have a coherent state among devices.

Note that you don't need to run the last step of driver notification
though (the actual "suspend" state), this will save you the disk
powercycle effect on suspend.

Ben.





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