Re: [PATCH] SCSI midlayer power management

[Pavel Machek]

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.
-- 
64 bytes from 195.113.31.123: icmp_seq=28 ttl=51 time=448769.1 ms         

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