[PATCH v1 2/4] ata: libata-scsi: Generate ATA PT sense data when ATA ERR/DF are set

[Igor Pylypiv <ipylypiv@google.com>]

SCSI/ATA Translation-5 (SAT-5) Table 209 — "ATA command results"
specifies that SATL shall generate sense data for ATA PASS-THROUGH
commands when either CK_COND is set or when ATA_ERR or ATA_DF status
bits are set.

ata_eh_analyze_tf() sets AC_ERR_DEV bit in qc->err_mask when ATA_ERR
or ATA_DF bits are set. It looks like qc->err_mask can be used as
an error indicator but ata_eh_link_autopsy() clears AC_ERR_DEV bit
when ATA_QCFLAG_SENSE_VALID is set. This effectively clears the error
indication if no other bits were set in qc->err_mask.

ata_scsi_qc_complete() should not use qc->err_mask for ATA PASS-THROUGH
commands because qc->err_mask can be zero (i.e. "no error") even when
the corresponding command has failed with ATA_ERR/ATA_DF bits set.

Additionally, the presence of valid sense data (ATA_QCFLAG_SENSE_VALID)
should not prevent SATL from generating sense data for ATA PASS-THROUGH.

Signed-off-by: Igor Pylypiv <ipylypiv@google.com>
---
 drivers/ata/libata-scsi.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 032cf11d0bcc..79e8103ef3a9 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -1632,8 +1632,8 @@ static void ata_scsi_qc_complete(struct ata_queued_cmd *qc)
 		!(qc->flags & ATA_QCFLAG_SENSE_VALID);
 
 	/* For ATA pass thru (SAT) commands, generate a sense block if
-	 * user mandated it or if there's an error.  Note that if we
-	 * generate because the user forced us to [CK_COND =1], a check
+	 * user mandated it or if ATA_ERR or ATA_DF bits are set. Note that
+	 * if we generate because the user forced us to [CK_COND=1], a check
 	 * condition is generated and the ATA register values are returned
 	 * whether the command completed successfully or not. If there
 	 * was no error, we use the following sense data:
@@ -1641,7 +1641,7 @@ static void ata_scsi_qc_complete(struct ata_queued_cmd *qc)
 	 * asc,ascq = ATA PASS-THROUGH INFORMATION AVAILABLE
 	 */
 	if (((cdb[0] == ATA_16) || (cdb[0] == ATA_12)) &&
-	    ((cdb[2] & 0x20) || need_sense))
+	    ((cdb[2] & 0x20) || (qc->result_tf.status & (ATA_ERR | ATA_DF))))
 		ata_gen_passthru_sense(qc);
 	else if (need_sense)
 		ata_gen_ata_sense(qc);
-- 
2.45.2.627.g7a2c4fd464-goog