Hi, Alan & All:
The 2.6.20-rc2 tree carries this patch (equivalent, actually):
> --- linux-2.6.18-1.2769.el5/drivers/usb/storage/scsiglue.c 2006-09-19
> 20:42:06.000000000 -0700
> +++ linux-2.6.18-1.2769.el5-ufi/drivers/usb/storage/scsiglue.c
> 2007-01-02 21:47:24.000000000 -0800
> @@ -72,12 +72,27 @@ static const char* host_info(struct Scsi
>
> 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;
> }
>
But it seems that I found a case when this does not work. It happens
with Sun's virtual floppy, which returns a seemingly normal INQUIRY
data (this is CBI, LUN set to 1, and device simply ignores it, most
likely):
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
So this got me wondering, why do we use such curiously complicated
way of trimming LUNs instead of something like this:
--- linux-2.6.18-1.2769.el5/drivers/usb/storage/usb.c 2006-09-19
20:42:06.000000000 -0700
+++ linux-2.6.18-1.2769.el5-ufi/drivers/usb/storage/usb.c 2007-01-03
17:57:24.000000000 -0800
@@ -692,6 +692,7 @@ static int get_protocol(struct us_data *
case US_SC_UFI:
us->protocol_name = "Uniform Floppy Interface (UFI)";
us->proto_handler = usb_stor_ufi_command;
+ us->max_lun = 0;
break;
#ifdef CONFIG_USB_STORAGE_ISD200
I verified this to work and solve my problem, whereas backporting the
code from 2.6.20-rc2 did not work.
Have anyone ever seen a multi-headed USB floppy?
-- Pete
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