On Thu, 4 Jan 2007, Pete Zaitcev wrote:
> On Thu, 4 Jan 2007 16:13:40 -0800, Matthew Dharm <[EMAIL PROTECTED]> wrote:
> > On Thu, Jan 04, 2007 at 04:01:19PM -0800, Pete Zaitcev wrote:
>
> > > ffff81003f5575c0 1779789944 S Co:004:00 s 21 00 0000 0000 000c 12 =
> > > 12200000 24000000 00000000
> > > ffff81003f5575c0 1779792226 C Co:004:00 0 12 >
> > > ffff8100374c2980 1779792240 S Bi:004:01 -115 36 <
> > > ffff8100374c2980 1779795215 C Bi:004:01 0 36 = 00800001 1f000000 414d4920
> > > 20202020 56697274 75616c20 466c6f70 70792020
> > > ffff81003f5575c0 1779795226 S Ii:004:03 -115 2 <
> > > ffff81003f5575c0 1779821221 C Ii:004:03 0 2 = 0000
> >
> > What exactly happens? I would assume that an error response to an INQUIRY
> > for LUN 1 would "Do the Right Thing".
>
> The exchange quoted above is exactly what happens. For the CBI transport,
> we ignore the LUN in srb->device->lun and simply pass the command on;
> the command has LUN bits set by the SCSI stack as if the command was
> directed at parallel SCSI (is it what they call SPI?).
Yes it is: SCSI Parallel Interface.
> This is discussed
> in UFI 3.2.2. The above example addresses LUN 1.
>
> The inquiry data is for something shipped by AMI (a BIOS company: apparently
> they diversified into all kinds of firmware). It claims legacy SCSI
> compliance (not even SCSI II).
The whole issue is complicated and entangled. For instance, right now we
have in slave_configure():
/* Set the SCSI level to at least 2. We'll leave it at 3 if that's
* what is originally reported. We need this to avoid confusing
* the SCSI layer with devices that report 0 or 1, but need 10-byte
* commands (ala ATAPI devices behind certain bridges, or devices
* which simply have broken INQUIRY data).
*
* NOTE: This means /dev/sg programs (ala cdrecord) will get the
* actual information. This seems to be the preference for
* programs like that.
*
* NOTE: This also means that /proc/scsi/scsi and sysfs may report
* the actual value or the modified one, depending on where the
* data comes from.
*/
if (sdev->scsi_level < SCSI_2)
sdev->scsi_level = sdev->sdev_target->scsi_level = SCSI_2;
The reasoning in the comment seems no longer to be correct, and it might
be a very good idea to get rid of this code entirely.
Pete's device is affected, since it has scsi_level equal to 0 (the three
low-order bits in the third byte of the INQUIRY response data). This
value does indeed mean "legacy SCSI", but usb-storage has transformed it
to SCSI-2.
Now, the SCSI core doesn't fill in the LUN bits in the second byte of a
CDB when scsi_level is 0. This is a required feature for certain types of
ATA pass-thru commands; they use those bits to mean something else.
We are led to the following reasoning:
CB and CBI can't pass the LUN value as a control parameter,
but only as part of the CDB.
If scsi_level is 0 then the LUN value won't be passed in the CDB.
Hence any device using CB or CBI with scsi_level == 0 _must_
be single-LUN.
Pete, I imagine this will solve your problem better than your proposed
change.
> > > Have anyone ever seen a multi-headed USB floppy?
> >
> > I've seen floppy/CF and floppy/CD-ROM combinations on multiple LUNs. I've
> > gotten e-mail from people with multiple-head floppies. I've never seen
> > one, personally.
>
> I think floppy/CF probably wasn't a UFI protocol thing... So my patch
> would continue to work. But a multi-head floppy sounds worrying.
> The UFI spec talks about LUNs as if they they ought to be used for
> something. But still, if nobody ever seen such things, I am willing
> to risk it.
The question isn't so much whether these devices are floppies; it's
whether they are UFI. I know, only floppy drives are supposed to use UFI
-- but there might be some that don't, and in any case vendors don't
always follow the rules.
So how does this patch grab you?
Alan Stern
Index: usb-2.6/drivers/usb/storage/scsiglue.c
===================================================================
--- usb-2.6.orig/drivers/usb/storage/scsiglue.c
+++ usb-2.6/drivers/usb/storage/scsiglue.c
@@ -110,23 +110,6 @@ static int slave_configure(struct scsi_d
* the end, scatter-gather buffers follow page boundaries. */
blk_queue_dma_alignment(sdev->request_queue, (512 - 1));
- /* Set the SCSI level to at least 2. We'll leave it at 3 if that's
- * what is originally reported. We need this to avoid confusing
- * the SCSI layer with devices that report 0 or 1, but need 10-byte
- * commands (ala ATAPI devices behind certain bridges, or devices
- * which simply have broken INQUIRY data).
- *
- * NOTE: This means /dev/sg programs (ala cdrecord) will get the
- * actual information. This seems to be the preference for
- * programs like that.
- *
- * NOTE: This also means that /proc/scsi/scsi and sysfs may report
- * the actual value or the modified one, depending on where the
- * data comes from.
- */
- if (sdev->scsi_level < SCSI_2)
- sdev->scsi_level = sdev->sdev_target->scsi_level = SCSI_2;
-
/* Many devices have trouble transfering more than 32KB at a time,
* while others have trouble with more than 64K. At this time we
* are limiting both to 32K (64 sectores).
@@ -176,7 +159,9 @@ static int slave_configure(struct scsi_d
* a Get-Max-LUN request, we won't lose much by setting the
* revision level down to 2. The only devices that would be
* affected are those with sparse LUNs. */
- sdev->scsi_level = sdev->sdev_target->scsi_level = SCSI_2;
+ if (sdev->scsi_level > SCSI_2)
+ sdev->scsi_level = sdev->sdev_target->scsi_level =
+ SCSI_2;
/* USB-IDE bridges tend to report SK = 0x04 (Non-recoverable
* Hardware Error) when any low-level error occurs,
@@ -194,6 +179,16 @@ static int slave_configure(struct scsi_d
sdev->use_10_for_ms = 1;
}
+ /* The CB and CBI transports have no way to pass LUN values
+ * other than the bits in the second byte of a CDB. But those
+ * bits don't get set to the LUN value if the device reports
+ * scsi_level == 0 (UNKNOWN). Hence such devices must necessarily
+ * be single-LUN.
+ */
+ if ((us->protocol == US_PR_CB || us->protocol == US_PR_CBI) &&
+ sdev->scsi_level == SCSI_UNKNOWN)
+ us->max_lun = 0;
+
/* Some devices choke when they receive a PREVENT-ALLOW MEDIUM
* REMOVAL command, so suppress those commands. */
if (us->flags & US_FL_NOT_LOCKABLE)
-------------------------------------------------------------------------
Take Surveys. Earn Cash. Influence the Future of IT
Join SourceForge.net's Techsay panel and you'll get the chance to share your
opinions on IT & business topics through brief surveys - and earn cash
http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV
_______________________________________________
linux-usb-devel@lists.sourceforge.net
To unsubscribe, use the last form field at:
https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
