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    SubjectRe: [PATCH] SCSI midlayer power management
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    Hi.

    On Thu, 2004-08-12 at 08:48, Nathan Bryant wrote:
    > Just to speculate about what would be required for swsusp: you probably
    > need to be using a SCSI LLD that properly implements pci suspend/resume,
    > which implies you need to make sure the card's DMA state machine is
    > flushed and idle before suspend completes. I've got a patch that fixes
    > this much up for aic7xxx. And my other midlayer-level patch may also
    > help... What happens during resume is interesting. I think maybe the
    > problem is not what the drive is expecting, but what the card's state
    > engine is expecting when it tries to map commands to command buffers in
    > DMA space. Maybe you need to suspend the LLD from the context of the
    > kernel that is doing the image load, and then resume from the context of
    > the kernel that was just loaded.

    I fully agree. That's what I'm doing at the moment; it's been a while
    since I looked at swsusp though, so can't say anything about Pavel &
    Patrick's implementation.

    > >With my 'device tree' code, I'm getting the struct dev of the device
    > >we're using via the struct block_device in the swap_info struct.
    > >
    > Right, though you also need to get the host adapter's struct device, if
    > you're not already doing so, that is. Many IDE host drivers don't bother
    > with suspend/resume callbacks at the pci_driver level, but SCSI needs
    > callbacks because the BIOS usually doesn't handle things for us.

    The host adapter isn't in the device's chain of parents?

    Nigel

    --
    Nigel Cunningham
    Christian Reformed Church of Tuggeranong
    PO Box 1004, Tuggeranong, ACT 2901

    Many today claim to be tolerant. But true tolerance can cope with others
    being intolerant.

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