libata: ATAPI command completion tweaks and notes

1) note urgent bug, that completes command twice

2) only fix up INQUIRY data if the SCSI version is zero (typically
indicates ATAPI MMC-ish device)

3) if there is a problem on the ATA bus, don't bother with REQUEST
SENSE, just directly handle the error based on Status/Error registers.

1 files changed, 28 insertions, 3 deletions

diff --git a/drivers/scsi/libata-scsi.c b/drivers/scsi/libata-scsi.c
index 45ebe9fd52ea..1a1ef3429e55 100644
--- a/drivers/scsi/libata-scsi.c
+++ b/drivers/scsi/libata-scsi.c
@@ -1483,9 +1483,18 @@ static int atapi_qc_complete(struct ata_queued_cmd *qc, u8 drv_stat)
 {
         struct scsi_cmnd *cmd = qc->scsicmd;
 
-        if (unlikely(drv_stat & (ATA_ERR | ATA_BUSY | ATA_DRQ))) {
+        if (unlikely(drv_stat & (ATA_BUSY | ATA_DRQ)))
+                ata_to_sense_error(qc, drv_stat);
+        else if (unlikely(drv_stat & ATA_ERR)) {
                 DPRINTK("request check condition\n");
 
+                /* FIXME: command completion with check condition
+                 * but no sense causes the error handler to run,
+                 * which then issues REQUEST SENSE, fills in the sense 
+                 * buffer, and completes the command (for the second
+                 * time).  We need to issue REQUEST SENSE some other
+                 * way, to avoid completing the command twice.
+                 */
                 cmd->result = SAM_STAT_CHECK_CONDITION;
 
                 qc->scsidone(cmd);
@@ -1499,10 +1508,26 @@ static int atapi_qc_complete(struct ata_queued_cmd *qc, u8 drv_stat)
                         unsigned int buflen;
 
                         buflen = ata_scsi_rbuf_get(cmd, &buf);
-                        buf[2] = 0x5;
-                        buf[3] = (buf[3] & 0xf0) | 2;
+
+        /* ATAPI devices typically report zero for their SCSI version,
+         * and sometimes deviate from the spec WRT response data
+         * format.  If SCSI version is reported as zero like normal,
+         * then we make the following fixups:  1) Fake MMC-5 version,
+         * to indicate to the Linux scsi midlayer this is a modern
+         * device.  2) Ensure response data format / ATAPI information
+         * are always correct.
+         */
+        /* FIXME: do we ever override EVPD pages and the like, with
+         * this code?
+         */
+                        if (buf[2] == 0) {
+                                buf[2] = 0x5;
+                                buf[3] = 0x32;
+                        }
+
                         ata_scsi_rbuf_put(cmd, buf);
                 }
+
                 cmd->result = SAM_STAT_GOOD;
         }