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  • Darrick J. Wong's avatar
    [SCSI] libsas: support NCQ for SATA disks · bdab4e87
    Darrick J. Wong authored
    This patch adds SATAII NCQ support to libsas.  Both the use_ncq and the
    dma_xfer flags in ata_task must be set for NCQ to work correctly on the
    Adaptec SAS controller.  The rest of the patch adds ATA_FLAG_NCQ to
    sata_port_info and sets up ap->scsi_host so that ata_setup_ncq doesn't
    crash.  Please note that this patch is against the aic94xx-sas git tree,
    not scsi-misc.  Thanks also to James Bottomley for providing an earlier
    version of this patch from which to work.
    I've tested this patch on a x206m with a ST380819AS SATA2 disk plugged
    into the Adaptec SAS controller.  The drive came up with a queue depth
    of 31, and I successfully ran an I/O flood test to coerce libata into
    sending multiple commands simultaneously.  A kernel probe recorded the
    maximum tag number that had been seen before and after the flood test;
    before the test it was 2 and after it was 30, as I expected.
    Signed-off-by: default avatarDarrick J. Wong <>
    Signed-off-by: default avatarJames Bottomley <>