[SCSI] Recognize missing LUNs for non-standard devices

Some non-standard SCSI targets or protocols, such as USB UFI, report "no
LUN present" by setting the Peripheral Device Type to 0x1f and the
Peripheral Qualifier to 0 (not 3 as the standard requires) in the INQUIRY
response.  This patch (as650b) adds a new target flag and code to
accomodate such targets.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

1 files changed, 13 insertions, 0 deletions

diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index 803c7b9690c5..94b86d5b1469 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -853,6 +853,19 @@ static int scsi_probe_and_add_lun(struct scsi_target *starget,
                 goto out_free_result;
         }
 
+        /*
+         * Non-standard SCSI targets may set the PDT to 0x1f (unknown or
+         * no device type) instead of using the Peripheral Qualifier to
+         * indicate that no LUN is present.  For example, USB UFI does this.
+         */
+        if (starget->pdt_1f_for_no_lun && (result[0] & 0x1f) == 0x1f) {
+                SCSI_LOG_SCAN_BUS(3, printk(KERN_INFO
+                                        "scsi scan: peripheral device type"
+                                        " of 31, no device added\n"));
+                res = SCSI_SCAN_TARGET_PRESENT;
+                goto out_free_result;
+        }
+
         res = scsi_add_lun(sdev, result, &bflags);
         if (res == SCSI_SCAN_LUN_PRESENT) {
                 if (bflags & BLIST_KEY) {