Re: USB multi card reader == SCSI multi lun target

Stephen J. Gowdy
2003-09-02T00:41:52Z

BTW, this is in the Linux USB FAQ;

http://www.linux-usb.org/FAQ.html#ts9

On Tue, 2 Sep 2003, Douglas Gilbert wrote:

> This is probably old news to USB folks but those
> nifty little USB multi card readers (e.g. CF, SD,
> MMC, SMC cards etc) appear in Linux as multi lun
> targets.
>
> Most distros only scan for lun 0 **. So to see
> luns > 0, commands like these are needed:
>
> echo "scsi add-single-device 1 0 0 1" > /proc/scsi/scsi
> echo "scsi add-single-device 1 0 0 2" > /proc/scsi/scsi
> echo "scsi add-single-device 1 0 0 3" > /proc/scsi/scsi
>
> The above sequence was needed for a 4 slot multi card reader.
> Following is some /proc/scsi/scsi output after an
> "scsi add-single-device 1 0 0 1" in a 2 slot multi card reader.
> Notice the end of the model string tells you what type of
> card is read at that lun.
>
> # cat /proc/scsi/scsi
> Attached devices:
> Host: scsi0 Channel: 00 Id: 02 Lun: 00
> Vendor: hp Model: scanjet 7400c Rev: 0.8A
> Type: Scanner ANSI SCSI revision: 02
> Host: scsi1 Channel: 00 Id: 00 Lun: 00
> Vendor: Generic Model: USB Storage-SMC Rev: 0090
> Type: Direct-Access ANSI SCSI revision: 02
> Host: scsi1 Channel: 00 Id: 00 Lun: 01
> Vendor: Generic Model: USB Storage-CFC Rev: 0090
> Type: Direct-Access ANSI SCSI revision: 02
>
>
> ** Most distros don't set CONFIG_SCSI_MULTI_LUN because some
> "scsi" devices answer all luns. I think that bug in ide-scsi
> has been fixed in lk 2.4.22 (I've sent patches to this list
> for 2.4 and 2.5 to fix this). A scipt may be useful to scan
> the output of /proc/scsi/scsi for this class of device and if
> found manually scan for luns > 0.
>
> Doug Gilbert
>
>
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