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    SubjectRe: sata suspend resume ...
    Hugh Dickins wrote:
    > --- 2.6.17-rc2/drivers/scsi/libata-core.c 2006-04-19 09:14:11.000000000 +0100
    > +++ linux/drivers/scsi/libata-core.c 2006-04-21 20:55:48.000000000 +0100
    > @@ -4288,6 +4288,7 @@ int ata_device_resume(struct ata_port *a
    > {
    > if (ap->flags & ATA_FLAG_SUSPENDED) {
    > ap->flags &= ~ATA_FLAG_SUSPENDED;
    > + ata_busy_sleep(ap, ATA_TMOUT_BOOT_QUICK, ATA_TMOUT_BOOT);
    > ata_set_mode(ap);
    > }


    This is helpful to narrow down the problem, but its a bit of a layering
    violation. In the current code, all functions called by
    ata_device_{suspend,resume}() are high level functions, which uses
    ata_qc_issue/ata_qc_complete high level API to address the device.

    In contrast, ata_busy_sleep() sticks its hands deep into the host state
    machine, and gives the tree a good hard shake. :) Consider that
    ata_busy_sleep() doesn't make sense for unusual cases like
    ATA-over-ethernet (AoE), or other tunnelled ATA transports.

    It may very well be that ata_busy_sleep() is the proper solution for
    your hardware, but it isn't applicable to all hardware.

    So you really want an ata_make_sure_bus_is_awake_and_working() called at
    that location. ata_busy_sleep()'s purpose is to bring a PATA-like bus
    to the bus-idle state. So, when working on suspend/resume, the software
    needs to have points at which the bus state is controlled/queried/asserted.

    Jeff


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