Re: [PATCH] libata: add support for NCQ commands for SG interface
From: Tejun Heo
Date: Thu Oct 22 2015 - 04:57:42 EST
Hello,
On Wed, Oct 21, 2015 at 10:39:32AM +0530, Vinayak Kale wrote:
...
> > diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
> > index 0d7f0da..5b0a5ab 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;
> > @@ -2963,7 +2965,7 @@ static unsigned int ata_scsi_pass_thru(struct ata_queued_cmd *qc)
> > tf->hob_lbal = cdb[7];
> > tf->hob_lbam = cdb[9];
> > tf->hob_lbah = cdb[11];
> > - tf->flags |= ATA_TFLAG_LBA48;
> > + tf->flags |= (ATA_TFLAG_LBA48 | ATA_TFLAG_LBA);
> > } else
> > tf->flags &= ~ATA_TFLAG_LBA48;
> >
> > @@ -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;
>
> Any comments on this?
It looks like it'd work given that it's forcing qc->tag into
tf->nsect. What's the use case tho?
Thanks.
--
tejun
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