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>

diff --git a/drivers/usb/storage/scsiglue.c b/drivers/usb/storage/scsiglue.c
index a4b7df9..e1072d5 100644 (file)
--- 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;
 }