Re: device_suspend() levels [was Re: [patch] ACPI work on aic7xxx]

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

> For suspend/resume and also initialization on bootup. We're not saving 
> the chip state for PIIX so I assume we're hoping that ACPI does it for us

ah, that part, yes, well, we hope ;) though it may just come back up
in the right state for normal PIO access, and we do restore the DMA
state by calling dma_check again in the ide-disk wakeup code.

> > We need to issue the stuff from the low level driver (like aix7xxx) or
> > the disk, that is sd, but we should make sure sg etc... also properly
> > call the stuff, actually, look at IDE, I defined the special power
> > request to act as a state machine once down the queue so the ide layer
> > acts differently for disks, cdroms, etc... by sending appropriate
> > commands like standby for disks.
> 
> There's another one - synchronize cache or disable write back cache on 
> the drive....

Yes, whatever. STANDBYNOW1 is enough on IDE (it does sync. the cache),
though I don't think we "restore" the state of the write back cache,
so that could be a good idea to add too :)

Ben