Laptop Function key (KEY_FN) not recognized by XWindows

Laptop Function key (KEY_FN) not recognized by XWindows

[Rakesh Iyer]

Hi All.

I am writing a Keyboard driver where the Function key (as seen in Laptop) is used as a modifier.
In my driver I have used "KEY_FN"(from include/linux/input.h) as the keycode for this key.

When I run "xev" the key press events do not get detected.
If I modify the keycode to say KEY_MEDIA, "xev" does show the event properly.

I am wondering how to go about getting this key detected and processed by XWindows.

Thanks and Regards
Rakesh
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Re: Laptop Function key (KEY_FN) not recognized by XWindows

[Dmitry Torokhov]

Hi Rakesh,

On Fri, Feb 04, 2011 at 05:05:50PM -0800, Rakesh Iyer wrote:
> Hi All.
> 
> I am writing a Keyboard driver where the Function key (as seen in Laptop) is used as a modifier.
> In my driver I have used "KEY_FN"(from include/linux/input.h) as the keycode for this key.
> 
> When I run "xev" the key press events do not get detected.
> If I modify the keycode to say KEY_MEDIA, "xev" does show the event properly.
> 
> I am wondering how to go about getting this key detected and processed by XWindows.

Yes, indeed, you are stumbling against limitation of X which does not
allow to pass keycodes above 255 through it.

One option would be assigning KEY_LEFTMETA or KEY_RIGHTMETA to your 'Fn'
key and then adjusting keymaps, but after I looked again at the keys you
have assigned by default to your Fn combinations  can see how one would
want to avoid involving X's keymaps and be able to generate needed
keycodes directly (volume, brightness and other control events) so that
infrastructure need not be hooked into X to be able to react to them.

I think if you implement a hard/soft-fn flag in platform data and, in
case of hard_fn mode would suppress KEY_FN event but rather treat it as
most significant bit in your row data (effectively doubling keymap size)
that would solve your issue.

What do you think?

Thanks.

-- 
Dmitry

RE: Laptop Function key (KEY_FN) not recognized by XWindows

[Rakesh Iyer]

> I think if you implement a hard/soft-fn flag in platform data and, in
> case of hard_fn mode would suppress KEY_FN event but rather treat it as
> most significant bit in your row data (effectively doubling keymap size)
> that would solve your issue.
> 
> What do you think?

That's an excellent suggestion. I think the max row size allows me to do exactly that (and nothing else :)).

Regards
Rakesh

> -----Original Message-----
> From: Dmitry Torokhov [mailto:dmitry.torokhov@gmail.com]
> Sent: Monday, February 07, 2011 10:48 AM
> To: Rakesh Iyer
> Cc: linux-input@vger.kernel.org
> Subject: Re: Laptop Function key (KEY_FN) not recognized by XWindows
> 
> Hi Rakesh,
> 
> On Fri, Feb 04, 2011 at 05:05:50PM -0800, Rakesh Iyer wrote:
> > Hi All.
> >
> > I am writing a Keyboard driver where the Function key (as seen in Laptop) is used as a
> modifier.
> > In my driver I have used "KEY_FN"(from include/linux/input.h) as the keycode for this
> key.
> >
> > When I run "xev" the key press events do not get detected.
> > If I modify the keycode to say KEY_MEDIA, "xev" does show the event properly.
> >
> > I am wondering how to go about getting this key detected and processed by XWindows.
> 
> Yes, indeed, you are stumbling against limitation of X which does not
> allow to pass keycodes above 255 through it.
> 
> One option would be assigning KEY_LEFTMETA or KEY_RIGHTMETA to your 'Fn'
> key and then adjusting keymaps, but after I looked again at the keys you
> have assigned by default to your Fn combinations  can see how one would
> want to avoid involving X's keymaps and be able to generate needed
> keycodes directly (volume, brightness and other control events) so that
> infrastructure need not be hooked into X to be able to react to them.
> 
> I think if you implement a hard/soft-fn flag in platform data and, in
> case of hard_fn mode would suppress KEY_FN event but rather treat it as
> most significant bit in your row data (effectively doubling keymap size)
> that would solve your issue.
> 
> What do you think?
> 
> Thanks.
> 
> --
> Dmitry
-----------------------------------------------------------------------------------
This email message is for the sole use of the intended recipient(s) and may contain
confidential information.  Any unauthorized review, use, disclosure or distribution
is prohibited.  If you are not the intended recipient, please contact the sender by
reply email and destroy all copies of the original message.
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