Bug#671292: [PATCH/RFC v2] HID: logitech: read all 32 bits of report type bitfield
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
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