Re: [PATCH/RFC v2] HID: logitech: read all 32 bits of report type bitfield

[Hugo Osvaldo Barrera <hugo@osvaldobarrera.com.ar>]

On 2012-05-11 04:39, Jonathan Nieder wrote:
> From: Nestor Lopez Casado <nlopezcasad@logitech.com>
> 
> On big-endian systems (e.g., Apple PowerBook), trying to use a
> logitech wireless mouse with the Logitech Unifying Receiver does not
> work with v3.2 and later kernels.  The device doesn't show up in
> /dev/input.  Older kernels work fine.
> 
> That is because the new hid-logitech-dj driver claims the device.  The
> device arrival notification appears:
> 
> 	20 00 41 02 00 00 00 00 00 00 00 00 00 00 00
> 
> and we read the report_types bitfield (02 00 00 00) to find out what
> kind of device it is.  Unfortunately the driver only reads the first 8
> bits and treats that value as a 32-bit little-endian number, so on a
> powerpc the report type seems to be 0x02000000 and is not recognized.
> 
> Even on little-endian machines, connecting a media center remote
> control (report type 00 01 00 00) with this driver loaded would
> presumably fail for the same reason.
> 
> Fix both problems by using get_unaligned_le32() to read all four
> bytes, which is a little clearer anyway.  After this change, the
> wireless mouse works on Hugo's PowerBook again.
> 
> Addresses http://bugs.debian.org/671292
> 
> [jn: with commit message and tweaked to use get_unaligned instead of
>  copying onto the stack]
> 
> Reported-by: Hugo Osvaldo Barrera <hugo@osvaldobarrera.com.ar>
> Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
> Cc: <stable@vger.kernel.org>
> ---
> Change since v1: fixed attribution.
> 
> I had been wondering why the patch you sent before didn't fix Hugo's
> problem while the effectively identical patch I sent did.  The only
> explanation I can think of is an error introduced in applying the
> patch by hand.
> 
<patch snipped>

I'd hate to think I screwed up applying such a simple patch, but it's
the only thing I can think of as well.

Thanks again to both of you for your time and effort, and for your
timely responses on this issue!

I hope this makes it to the main branch soon!

Cheers, and good luck to both,

-- 
Hugo Osvaldo Barrera