Re: [PATCH] SCSI midlayer power management

Pavel Machek
2004-08-11T20:29:37Z

Hi!

> >swsusp will then resume disk and write the image, that should not be
> >a
> >problem. Is it guaranteed that after generic_scsi_suspend() no DMA is
> >going on?
> >
> >
> No. Remember that DMA works differently under SCSI than it does under
> IDE. SCSI DMA is a host controller feature, whereas under IDE it is
> enabled/disabled at the drive level and the drives have special
> knowledge of DMA. Since generic_scsi_suspend() is the device level
> suspend routine, it is called before the host controller's suspend
> routine, (due to depth first traversal of device tree), which is
> responsible for disabling the PCI slot. Only after the host
> controller is suspended will there be no DMA, but if your real
> question is "can I generically control a SCSI disk with PIO for
> software suspend" then the answer is NO. For purposes of not

No, I do not need PIO. I'll probably need host
controller support, too, but even w/o it it should
work acceptably. Thanks for the answers.
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