Re: 2.6.20-rc6 pb_fnmode regression

From: Soeren Sonnenburg
Date: Mon Jan 29 2007 - 06:24:58 EST


On Mon, 2007-01-29 at 12:13 +0100, Jiri Kosina wrote:
> On Mon, 29 Jan 2007, Jiri Kosina wrote:
>
> > Ah, now I see. The problem is that in pre-2.6.20-rc1 the pb_fnmode was
> > setting global variable, but after the HID layer rework, this is a
> > per-hid variable, which is of course not updated when write to sysfs
> > triggers. I will try to fix this before I send 2.6.20-rc6 updates to
> > Linus, thanks for pointing this out.
>
> Actually the cleanest solution would be when I change the code in such a
> way that pb_fnmode parameter would be passed to hid instead of usbhid
> module, as this is where the input mapping is being done (you could
> potentially have a keyboard which needs the very same handling of fn mode
> as usb powerbook keyboards currently have, but on different transport
> - input mapping is logically transport independent).
>
> But I guess you will be not OK with breaking the backward compatibility in
> such way, because all the already existing tutorials, etc. right?

That sounds good for me. Breaking with what was there is not a problem
as long as this feature is still there, it can be done in a more clean
way this way, and the new /sys/foo/bar path is documented (basically
people nowadays expect slight user interface changes between kernel
versions).

> Would warning that would trigger when the module parameter is passed to
> usbhid and would instruct user to pass the parameter to hid module
> instead, be acceptable? (and then changing the parameter of hid module
> through sysfs would work as expected again).

I guess this warning is not too useful, except if it is triggered on
echo >/sys/*/pb_fnmode too (which I suspect is what most people do).

Soeren
--
Sometimes, there's a moment as you're waking, when you become aware of
the real world around you, but you're still dreaming.
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