[PATCH v2] libata: add support for NCQ commands for SG interface

From: vinayak . kale
Date: Tue Oct 27 2015 - 01:50:16 EST


From: Vinayak Kale <vinayak.kale@xxxxxxxxxxx>

This patch is needed to make NCQ commands with FPDMA protocol value
(eg READ/WRITE FPDMA) work over SCSI Generic (SG) interface.

Signed-off-by: Vinayak Kale <vinayak.kale@xxxxxxxxxxx>
---
Changes in v2:
- Decoupled tf->flags changes in ata_scsi_pass_thru() from this patch
as per Tejun's suggestion. A separate patch will be sent for that change.

drivers/ata/libata-scsi.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 0d7f0da..c2af592 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -2914,12 +2914,14 @@ ata_scsi_map_proto(u8 byte1)
case 5: /* PIO Data-out */
return ATA_PROT_PIO;

+ case 12: /* FPDMA */
+ return ATA_PROT_NCQ;
+
case 0: /* Hard Reset */
case 1: /* SRST */
case 8: /* Device Diagnostic */
case 9: /* Device Reset */
case 7: /* DMA Queued */
- case 12: /* FPDMA */
case 15: /* Return Response Info */
default: /* Reserved */
break;
@@ -2992,6 +2994,10 @@ static unsigned int ata_scsi_pass_thru(struct ata_queued_cmd *qc)
tf->command = cdb[9];
}

+ /* For NCQ commands with FPDMA protocol, copy the tag value */
+ if (tf->protocol == ATA_PROT_NCQ)
+ tf->nsect = qc->tag << 3;
+
/* enforce correct master/slave bit */
tf->device = dev->devno ?
tf->device | ATA_DEV1 : tf->device & ~ATA_DEV1;
--
1.9.1

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