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    SubjectSATA suspend/resume (was Re: [PATCH] updated version of Jens' SATA suspend-to-ram patch)
    Joshua Kwan wrote:
    > Hello,
    >
    > I had some time yesterday and decided to help Jens out by rediffing the
    > now-infamous SATA suspend-to-ram patch [1] against current git and
    > test-building it.
    >
    > For posterity,
    >
    > This patch adds the ata_scsi_device_resume and ata_scsi_device_suspend
    > functions (along with helpers) to put to sleep and wake up Serial ATA
    > controllers when entering sleep states, and hooks the functions into
    > each SATA controller driver so that suspend-to-RAM is possible.
    >
    > Note that this patch is a holdover patch until it is possible to
    > generalize this concept for all SCSI devices, which requires more data
    > on which devices need to be put to sleep and which don't.
    >
    > Signed-off-by: Joshua Kwan <joshk@triplehelix.org>

    Ah hah! I found the other SCSI suspend patch:

    http://lwn.net/Articles/97453/

    Anybody (Joshua?) up for reconciling and testing the two?

    The main change from Jens/Joshua's patch is that we use SCSI's
    sd_shutdown() to call sync cache, eliminating the need for
    ata_flush_cache(), since the SCSI layer would now perform that.

    For bonus points,

    1) sd should call START STOP UNIT on suspend, which eliminates the need
    for ata_standby_drive(), and completely encompasses the suspend process
    in the SCSI layer.

    2) sd should call START STOP UNIT on resume -- and as a SUPER BONUS, the
    combination of these two changes ensures that there are no queue
    synchronization issues, the likes of which would require hacks like
    Jens' while-loop patch.

    None of these are huge changes requiring a lot of thinking/planning...

    Finally, ideally, we should be issuing a hardware or software reset on
    suspend.

    Jeff


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