Re: [PATCH 2/2] Input: Adding DT support for keyreset tuneables

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

On Wednesday, July 10, 2013 10:50:26 PM Grant Likely wrote:
> On Wed, Jul 10, 2013 at 5:52 PM, Dmitry Torokhov
> 
> <dmitry.torokhov@gmail.com> wrote:
> > On Wed, Jul 10, 2013 at 04:14:57PM +0100, Grant Likely wrote:
> >> On Fri, 28 Jun 2013 07:19:06 -0600, Mathieu Poirier 
<mathieu.poirier@linaro.org> wrote:
> >> > On 13-06-28 12:09 AM, Dmitry Torokhov wrote:
> >> > >>>> I do not agree.  We want the binding to be generic and not tied
> >> > >>>> specifically to the keyreset functionality.  As such
> >> > >>>> 'input-keyset' or
> >> > >>>> 'input-keychord' are more appropriate.
> >> > >>> 
> >> > >>> The binding is defined specifically for sysrq and specifically to
> >> > >>> perform reset action.
> >> > >> 
> >> > >> Yes for now but as the examples in the binding show, it is easy to
> >> > >> envision how other drivers could use it.
> >> > > 
> >> > > I think you over-complicate things here. Unlike matrix-keypad
> >> > > binding,
> >> > > where you have a common parsing code, here we have an individual
> >> > > driver.
> >> > > I really do not see anyone else using such sequences or chords as
> >> > > such
> >> > > processing should be done in userspace. Sysrq is quite an exception.
> >> > 
> >> > To be honest I don't have a very strong opinion on the binding.  I made
> >> > it as generic as possible on the guidance of the DT people.  Let's see
> >> > what they think of it.
> >> 
> >> Hi Mathieu,
> >> 
> >> As per our conversation just now at Connect, the binding should probably
> >> look like this:
> >> 
> >> Sysrq keyset binding:
> >> 
> >> The /chosen node can contain a linux,input-keyset-sysrq child node to
> >> define a set of keys that will generate a sysrq when pressed together.
> > 
> > Hmm, we would have only one such node, /sysrq, or /linux,sysrq,
> > whatever. The sysrq setting is system-wide and applicable to all
> > devices. Given that it is used only on mobile, where there not that
> > many input devices (a few keys and touchscreen) I do not believe we
> > should consider adding per-device settings.
> 
> It's in /chosen, that isn't per-device.
> 
> >> Required properties:
> >> keyset: array of keycodes
> > 
> > Please, let's call it 'key-reset-seq', because it is exactly the reset
> > sequence. There won't be any additional sequences or chords as those
> > should be handled in userspace, sysrq is a special case here.
> 
> This is absolutely a linux-specific binding. It encodes the Linux
> keycodes, and generates a linux meaning. I'm usually all about
> carrying the OS-independent banner when defining DT bindings, but in
> this case the linux prefix and sysrq reference is completely
> appropriate.

OK, I have no idea what "/chosen" actually means. What I am trying to say
that there should be either "sysrq" or "linux,sysrq" node and that is what
sysrq driver will be looking for.

The entire node is Linux-specific and therefore there is no point in
marking only one of the properties (the key sequence) Linux-specific while
leaving other ones generic.

Thanks.

-- 
Dmitry