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

On 10 July 2013 16:20, Dmitry Torokhov [off-list ref] wrote:

On Wednesday, July 10, 2013 10:50:26 PM Grant Likely wrote:

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On Wed, Jul 10, 2013 at 5:52 PM, Dmitry Torokhov

[off-list ref] wrote:

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On Wed, Jul 10, 2013 at 04:14:57PM +0100, Grant Likely wrote:

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On Fri, 28 Jun 2013 07:19:06 -0600, Mathieu Poirier

[off-list ref] wrote:

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On 13-06-28 12:09 AM, Dmitry Torokhov wrote:

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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

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perform reset action.

Yes for now but as the examples in the binding show, it is easy

to

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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.

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To be honest I don't have a very strong opinion on the binding.  I

made

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it as generic as possible on the guidance of the DT people.  Let's

see

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what they think of it.

Hi Mathieu,

As per our conversation just now at Connect, the binding should

probably

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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.

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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.

Chosen pertains to system wide parameters that aren't related to hw
specific devices.  Correct, the driver will look exactly for
"linux,sysrq-reset-seq" in the "chosen" node and nowhere else.

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