usb-storage: fix for UFI LUN detection

The UFI specification doesn't permit devices to indicate non-existent
LUNs in the manner prescribed by the SCSI spec.  This patch (as773)
sets a special flag so that the SCSI scanner will recognize these
devices and treat them specially.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Matthew Dharm <mdharm-usb@one-eyed-alien.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 15 insertions, 0 deletions

diff --git a/drivers/usb/storage/scsiglue.c b/drivers/usb/storage/scsiglue.c
index a4b7df9ff8c1..e1072d52d641 100644
--- a/drivers/usb/storage/scsiglue.c
+++ b/drivers/usb/storage/scsiglue.c
@@ -72,12 +72,27 @@ static const char* host_info(struct Scsi_Host *host)
 
 static int slave_alloc (struct scsi_device *sdev)
 {
+        struct us_data *us = host_to_us(sdev->host);
+
         /*
          * Set the INQUIRY transfer length to 36.  We don't use any of
          * the extra data and many devices choke if asked for more or
          * less than 36 bytes.
          */
         sdev->inquiry_len = 36;
+
+        /*
+         * The UFI spec treates the Peripheral Qualifier bits in an
+         * INQUIRY result as reserved and requires devices to set them
+         * to 0.  However the SCSI spec requires these bits to be set
+         * to 3 to indicate when a LUN is not present.
+         *
+         * Let the scanning code know if this target merely sets
+         * Peripheral Device Type to 0x1f to indicate no LUN.
+         */
+        if (us->subclass == US_SC_UFI)
+                sdev->sdev_target->pdt_1f_for_no_lun = 1;
+
         return 0;
 }