Re: [PATCH] Input: cros_ec_keyb: Add support for a front proximity switch

From: Pavel Machek <pavel@ucw.cz>
To: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Doug Anderson <dianders@chromium.org>,
	Stephen Boyd <swboyd@chromium.org>,
	Enric Balletbo i Serra <enric.balletbo@collabora.com>,
	Benson Leung <bleung@chromium.org>,
	LKML <linux-kernel@vger.kernel.org>,
	"open list:HID CORE LAYER" <linux-input@vger.kernel.org>,
	Guenter Roeck <groeck@chromium.org>
Subject: Re: [PATCH] Input: cros_ec_keyb: Add support for a front proximity switch
Date: Tue, 2 Feb 2021 14:43:59 +0100	[thread overview]
Message-ID: <20210202134359.GA25474@duo.ucw.cz> (raw)
In-Reply-To: <X/dlKKeAHU/Ab+VD@google.com>

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Hi!

> > > > Reviewed-by: Douglas Anderson <dianders@chromium.org>
> > > >
> > > > Given that it touches a header file owned by the Chrome OS maintainers
> > > > and a driver owned by input, how should it land?  One maintainer Acks
> > > > and the other lands?
> > >
> > > Sorry about missing this one, however the "front proximity" switch has
> > > been introduced for the benefit of phone devices, to be emitted when a
> > > device is raised to user's ear, and I do not think we should be using
> > > this here.
> > >
> > > We have just recently had similar discussion with regard to palm- and
> > > lap-mode sensors and whether they should be reported over input or IIO
> > > as true proximity sensors:
> > >
> > > https://lore.kernel.org/linux-iio/9f9b0ff6-3bf1-63c4-eb36-901cecd7c4d9@redhat.com/
> > >
> > > Based on what we are doing for other Chrome OS devices that expose
> > > proximity sensors (for example trogdor) we have decided that we all
> > > should be using IIO as it will allow not only on/off, but true proximity
> > > reporting with potential of implementing smarter policies by userspace.
> > >
> > > Because of that we should do the same here and export this as IIO
> > > proximity sensor as well.
> > 
> > For devices with a true proximity sensor that's exactly what we're
> > doing.  I've only been involved in the periphery of the discussion,
> > but as I understand it there are some models of laptop for which we
> > don't have a true proximity sensor.  On these devices, the EC is in
> > charge of deciding about proximity based on a number of factors.
> 
> Yes, I understand that on some devices the proximity sensors are not
> true sensors but rather on/off signals, potentially derived from a
> multitude of sources. However there is still a benefit in exposing them
> as IIO proximity devices with limited reporting representing
> [near, infinity] range/values. This will mean that userspace needs to
> monitor only one set of devices (IIO) instead of both IIO and input, and
> will not require constantly expanding EV_SW set to account for
> ever-growing number of proximity sensors (lap, palm, general presence,
> etc).

While I believe one set of devices is good goal, I don't think IIO is
good solution here. It is being used for user input after
all... Routing on/off values to IIO is strange.

Best regards,
									Pavel

-- 
http://www.livejournal.com/~pavelmachek

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