Re: [PATCH v2 3/8] input: misc: Add driver for AXP20x Power Enable Key

From: Lee Jones <lee.jones-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
To: Maxime Ripard
	<maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
Cc: Carlo Caione <carlo-KA+7E9HrN00dnm+yROfE0A@public.gmane.org>,
	linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org,
	linux-sunxi-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org,
	hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org,
	emilio-0Z03zUJReD5OxF6Tv1QG9Q@public.gmane.org,
	wens-jdAy2FN1RRM@public.gmane.org,
	sameo-VuQAYsv1563Yd54FQh9/CA@public.gmane.org,
	devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	dmitry.torokhov-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org,
	linux-input-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	lgirdwood-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org,
	broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org
Subject: Re: [PATCH v2 3/8] input: misc: Add driver for AXP20x Power Enable Key
Date: Tue, 18 Mar 2014 10:58:51 +0000	[thread overview]
Message-ID: <20140318105851.GO25478@lee--X1> (raw)
In-Reply-To: <20140318101554.GZ27873@lukather>

> > > > This patch add support for the Power Enable Key found on MFD AXP202 and
> > > > AXP209. Besides the basic support for the button, the driver adds two
> > > > entries in sysfs to configure the time delay for power on/off.
> > > > 
> > > > Signed-off-by: Carlo Caione <carlo-KA+7E9HrN00dnm+yROfE0A@public.gmane.org>
> > > > ---
> > > >  drivers/input/misc/Kconfig      |  11 ++
> > > >  drivers/input/misc/Makefile     |   1 +
> > > >  drivers/input/misc/axp20x-pek.c | 267 ++++++++++++++++++++++++++++++++++++++++
> > > >  3 files changed, 279 insertions(+)
> > > >  create mode 100644 drivers/input/misc/axp20x-pek.c
> > > 
> > > From what I understood of the MFD framework, you usually have a MFD
> > > core driver that gets loaded from the DT and instantiate its various
> > > functions through sub-devices, that are registered through
> > > mfd_add_devices, and the drivers for these sub-devices are supported
> > > in sub-drivers that are located in the driver/mfd, alongside the core
> > > driver.
> > > 
> > > I believe that such a pattern allows for two interesting things:
> > >   - You don't have to search around the whole kernel tree to find
> > >     where a given sub-feature is supported.
> > >   - You don't have to cripple your DT with instantiation of all the
> > >     subcomponents, while you only really have one device.
> > > 
> > > Do you have a reason for not following this pattern?
> > 
> > Sorry Maxime, this is not the case.
> > 
> > If an MFD contains Regulators and USB & GPIO Controllers, I'd expect
> > to see the device represented in the following way:
> > 
> >   drivers/mfd/<id>.c
> >   drivers/{gpio,pinctrl}/{gpio,pinctrl}-<id>.c
> >   drivers/regulator/<id>-regulator.c
> >   drivers/usb/host/<id>.c
> 
> Oh, ok. Nevermind then :)
> 
> Just out of curiosity, some drivers at least seem to follow that trend
> in drivers/mfd, is there any reason for this (other than historical) ?

Would you mind providing an example?

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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