Re: HID-generic + HID-ANOTHER interaction problems

On 16 November 2012 16:37, Jiri Kosina [off-list ref] wrote:

On Fri, 16 Nov 2012, Adam Sutton wrote:

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2. Sure I can see about doing that :) Maybe you could have a quick look at
the code here (
https://github.com/OpenELEC/OpenELEC.tv/blob/master/packages/linux/patches/linux-3.6.6-053-spinelplus-remote-0.1.patch)
to see if there is anything needs changing (the hid_have_special_driver[]
mods aside) before it will be accepted.

The driver looks fine, but as it contains solely usage -> keycode mapping,
it should be possible to do it completely in userspace. There are already
a lot of udev rules for this you can use for inspiration -- in recent udev
releases they are located in /lib/udev/rules.d/keymaps, and are handled by
master /lib/udev/rules.d/*keymap* rule.

I'll take a look at that. I can see there are plenty of other drivers
though in the mainline that do the same thing we're doing with the
spinelplus. Are these simply relics of and older approach (before udev
updates?) or is there a benefit to doing this in the kernel?

Exactly as you mention, it's a relic from the times when you were not able
to change HID usages by 'setkeycodes', so the in-kernel driver changing
the mapping was the only option.

Now there are much more mappings being done from userspace instead of the
kernel, but we can't really remove the ones which are already in-kernel,
as that might cause regressions for people with old udev whould would
update to latest kernel.

Thanks for the clarification.

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Either way would you still be happy to accept the patch? And if so
what exactly is the process for submitting, I've had a quick read
on-line. Do I simply need to generate a git patch and post to the
mailing list?

Yes, that is the usual process.

But for these kinds of drivers, I'd really suggest you actually convert it
to a udev rule and submit it as a patch to udev maintainers instead.

Does that work for you?

Yes I think it does. Short term I've simply fixed the patch to mod
hid-core.c as you suggested, that will solve the immediate problem.

I'll talk to Stephen about the fact he might want to consider
investigating use of udev keymap rules. I had a quick look on my
laptop and they looked simply enough to do.

Thanks for all the help,

Adam