Re: Using EV_MSC or extending KEY_*

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

On Fri, Sep 18, 2009 at 09:40:23AM -0600, Rick L. Vinyard, Jr. wrote:
> Dmitry Torokhov wrote:
> > On Thu, Sep 17, 2009 at 02:57:07PM -0300, Henrique de Moraes Holschuh
> > wrote:
> >> On Wed, 16 Sep 2009, Rick L. Vinyard, Jr. wrote:
> >> > The M* keys are intended to provide a quick way to switch between key
> >> > mappings, with each mode having their own user-defined mappings.
> >>
> >> What I'd do in this case would be this:
> >>
> >> 1. Initially have the M* level-shift keys assigned KEY_RESERVED
> >>
> >> 2. Have a big enough keymap to map all keys in all M*-level shift states
> >> possible.
> >>
> >> Eg:
> >>    START OF KEYMAP
> >>    M* keys
> >>    1st set of G* keys
> >>    2nd set of G* keys
> >>    3rd set of G* keys...
> >>    ...
> >>    last set of G* keys
> >>    END OF KEYMAP
> >>
> >> 3. Have the driver special-process M* level-shift keys *as long as they
> >> are
> >> still set to KEY_RESERVED* to select which part of the keymap is used to
> >> translate the other keys.  Note that this likely means pressing a M* key
> >> would be transparent to userspace in this case, i.e. no events would be
> >> issued when a M* key is doing a level shift.
> >>
> >> So, you'd be able to set all mappings you want in the driver, and the M*
> >> keys would do what they're expected to do without any userland help at
> >> all,
> >> but you'd still be able to program the M* keys to be normal keys if you
> >> want.
> >>
> >> Of course, this assumes you don't do chording on multiple M* keys to end
> >> up
> >> with a huge number of keymaps :p
> >>
> >
> > Actually I think that the device should just emit KEY_PROG1..KEY_PROG4
> > for the M keys and have userspace daemon load alternate keymaps on the
> > fly in resaponse to KEY_PROGx. The device is just a set of completely
> > generic buttons... User will have to tell the kernel what to map them
> > to.
> >
> 
> Emitting a keycode certainly does simplify things, but that will preclude
> the user from programming the G-keys to KEY_PROG1..KEY_PROG4.
> 
> Are there any specific use cases where a user would want to program a
> G-key to KEY_PROG1..KEY_PROG4?
> 

I an not sure, but if they want to use KEY_PROG* somewhere else they can
reprogram the M* keys to somethis other as well.

-- 
Dmitry