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.

diff --git a/drivers/scsi/libata-scsi.c b/drivers/scsi/libata-scsi.c
index 45ebe9fd52eaaccf38d9b96a0b90b39879a58d60..1a1ef3429e55f99ac91dbffb7a281c05c7922e22 100644 (file)
--- 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;
        }