[SCSI] libsas: support NCQ for SATA disks
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: Darrick J. Wong <djwong@us.ibm.com> Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
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