Question about bcdDevice_(lo|hi)

Question about bcdDevice_(lo|hi)

[Marcus Harnisch]

Hi List,

I just started to use linux hotplug (2001_09_19). When I tried to find
the reason why no map-entry for my camcorder matches, I came across
something I really don't understand.

usb.agent matches the bcdDevice columns in a map file using the
following statements:

    : bcdDevice range $bcdDevice_hi $bcdDevice_lo actual $usb_bcdDevice
    if [ $USB_MATCH_DEV_LO -eq $(( $match_flags & $USB_MATCH_DEV_LO )) ] &&
       [ $usb_bcdDevice -lt $bcdDevice_lo ]; then
        continue
    fi

    # bcdDevice_lo <= bcdDevice < bcdDevice_hi
    if [ $USB_MATCH_DEV_HI -eq $(( $match_flags & $USB_MATCH_DEV_HI )) ] &&
       [ $usb_bcdDevice -ge $bcdDevice_hi ]; then
        continue
    fi

The according entries in the map-files for all devices are a 4-digit
hexnumber for bcdDevice_lo and a 2-digit hexnumber for
bcdDevice_hi. With *very* few exceptions if bcdDevice that is greater
or equal to bcdDevice_lo (first condition) it is also greater than
bcdDevice_hi. This causes no match to be found in the vast majority of
cases (Þvices).

In my particular case, bcdDevice is 0x0300. So for test purposes I set
up an entry in usb.usermap with bcdDevice_lo to 0x0300. Which 2-digit
hexnumber would match the second condition? When I set bcdDevice_hi to
any number (well, I didn't try all of 'em :) above 0x02ff, everything
worked fine.

I really can't believe that this is a bug that nobody has seen
before. Can somebody explain that to me?

Best regards,
     Marcus


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Re: Question about bcdDevice_(lo|hi)

[David Brownell]

> The according entries in the map-files for all devices are a 4-digit
> hexnumber for bcdDevice_lo and a 2-digit hexnumber for
> bcdDevice_hi. 

Not on my system -- they're all four digits.  Is it possible you have
the wrong version of "modutils"?  So far as I know, this syntax has
not changed since modutils 2.4.1 ... previous versions don't work
correctly with 2.4.x kernels.

- Dave



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Re: Question about bcdDevice_(lo|hi)

[Marcus Harnisch]

Hi David,

Meanwhile I noticed that these numbers in the map files have indeed
four digits. I don't know what exactly happened here. Maybe I was off
by one column. The titles in the file usb.handmap that comes with
hotplug are (mis)aligned so that the title `bcdDevice_hi' is above the
column of `bDeviceClass' which has only two digits.

I got it to work anyway, so never mind.

Best regards,
      Marcus


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