Re: [PATCH v1 3/4] ata: libata-scsi: Report valid sense data for ATA PT if present

[Igor Pylypiv <ipylypiv@google.com>]

On Mon, Jun 17, 2024 at 12:49:47PM +0200, Niklas Cassel wrote:
> On Fri, Jun 14, 2024 at 07:18:34PM +0000, Igor Pylypiv wrote:
> > Do not generate sense data from ATA status/error registers
> > if valid sense data is already present.
> > 
> > Signed-off-by: Igor Pylypiv <ipylypiv@google.com>
> > ---
> >  drivers/ata/libata-scsi.c | 17 +++++++++++------
> >  1 file changed, 11 insertions(+), 6 deletions(-)
> > 
> > diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
> > index 79e8103ef3a9..4bfe47e7d266 100644
> > --- a/drivers/ata/libata-scsi.c
> > +++ b/drivers/ata/libata-scsi.c
> > @@ -858,12 +858,17 @@ static void ata_gen_passthru_sense(struct ata_queued_cmd *qc)
> >  	unsigned char *desc = sb + 8;
> >  	u8 sense_key, asc, ascq;
> 
> Like I suggested in the earlier patch,
> 
> can't you do a:
> 
> if (qc->flags & ATA_QCFLAG_SENSE_VALID)
> 	return;
> 
> here instead?
> 

We need to populate the "ATA Status Return sense data descriptor" as per SAT-5
"Table 209 — ATA command results". By returning early we are skipping the code
that copies ATA output fields into descriptor/fixed sense data buffer.

> 
> >  
> > -	/*
> > -	 * Use ata_to_sense_error() to map status register bits
> > -	 * onto sense key, asc & ascq.
> > -	 */
> > -	if (qc->err_mask ||
> > -	    tf->status & (ATA_BUSY | ATA_DF | ATA_ERR | ATA_DRQ)) {
> > +	if (qc->flags & ATA_QCFLAG_SENSE_VALID) {
> > +		/*
> > +		 * Do not generate sense data from ATA status/error
> > +		 * registers if valid sense data is already present.
> > +		 */
> > +	} else if (qc->err_mask ||
> > +		   tf->status & (ATA_BUSY | ATA_DF | ATA_ERR | ATA_DRQ)) {
> > +		/*
> > +		 * Use ata_to_sense_error() to map status register bits
> > +		 * onto sense key, asc & ascq.
> > +		 */
> >  		ata_to_sense_error(qc->ap->print_id, tf->status, tf->error,
> >  				   &sense_key, &asc, &ascq);
> >  		ata_scsi_set_sense(qc->dev, cmd, sense_key, asc, ascq);
> > -- 
> > 2.45.2.627.g7a2c4fd464-goog
> >