2.2 bcdDevice munging patch

[Plato <tom@redant.freeserve.co.uk>]

Sorry for the broken thread, but I've only just subscribed to the list.

Dave:
> Sounds fair to me.  Though it'll need to be a bit smarter, since I
> think the current code says "if the kernel is 2.2 then ..." and it'd
> have to change to handle two types of 2.2 kernels (original, new).

That's not necessary.  usb.agent only cares which kernel version is running
when deciding which of $MAP_CURRENT or $MAP_DISTMAP to use.

The code which munges the bcdDevice number is kernel independent. It
will not change a four hex-digit number specified by a 2.4 kernel, but will
change a number with a decimal point from a 2.2 kernel.

> That is, the newer 2.2 kernels would need updated hotplug scripts.

If 2.2.21 produced a four hex-digit number it would _not_ need an update to
my patch.

Greg:
> I'd recommend fixing the 2.2 kernel code to work the same way as 2.4.x.
> The hotplug code was enabled right at the end of the 2.2.20 development
> cycle, and this problem must have slipped through.

The problem has been solved now in userspace.  If my patch is implemented
then `broken' 2.2 kernels will work, along with 2.4, and later 2.2 kernels
possibly incorporating a fix.

The munging already exists.  Unfortunately it does not work for all possible
values of bcdDevice.  If you are going to continue to support 2.2 kernels
you should fix this.  I believe my patch fixes this.

The problem, for those of you that are not aware, is due to a difference in
the PRODUCT environment variable for use by the usb.agent between 2.2 and 2.4 kernels.
PRODUCT is of the form xxxx/xxxx/xxxx, i.e four hex numbers separated by
slashes.

The 2.4 kernel specifies the third of these numbers as `abcd', where a, b, c,
d are four hex digits.

The 2.2 kernel specifies the third of these numbers as `ab.cd'
It also omits a and d if they are zero.

There is a `munge' in the current usb.agent which seeks to rectify this. 
Unfortunately it does not seem to work for some cases, e.g.
PRODUCT=.../.../10.0

I'd be happy to hear any comments that you may have.  Keep up the good work!

Plato

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