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From: Frank Lee <tiny.windzz@gmail.com>
To: Icenowy Zheng <icenowy@aosc.io>
Cc: Maxime Ripard <maxime.ripard@bootlin.com>,
	Jonathan Cameron <jic23@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	devicetree@vger.kernel.org, lars@metafoo.de,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	linux-iio@vger.kernel.org, Chen-Yu Tsai <wens@csie.org>,
	robh+dt@kernel.org, pmeerw@pmeerw.net, knaack.h@gmx.de,
	Lee Jones <lee.jones@linaro.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH 1/7] iio: adc: sun4i-gpadc: rework for support multiple thermal sensor
Date: Tue, 7 May 2019 01:08:39 +0800	[thread overview]
Message-ID: <CAEExFWusPoxtkGCoA+3gXq69cXZEfjZW+UpHW_0UfrcjpLmaXg@mail.gmail.com> (raw)
In-Reply-To: <282ccf0979e6c58effd0e177917bdf824c32f64e.camel@aosc.io>

On Tue, May 7, 2019 at 12:52 AM Icenowy Zheng <icenowy@aosc.io> wrote:
>
> 在 2019-05-06一的 14:28 +0200,Maxime Ripard写道:
> > Hi,
> >
> > On Sun, May 05, 2019 at 04:22:15PM +0100, Jonathan Cameron wrote:
> > > On Fri,  3 May 2019 03:28:07 -0400
> > > Yangtao Li <tiny.windzz@gmail.com> wrote:
> > >
> > > > For some SOCs, there are more than one thermal sensor, and there
> > > > are
> > > > currently four sensors on the A80. So we need to do some work in
> > > > order
> > > > to support multiple thermal sensors:
> > > >
> > > >   1) add sensor_count in gpadc_data.
> > > >   2) introduce sun4i_sensor_tzd in sun4i_gpadc_iio, to support
> > > > multiple
> > > >      thermal_zone_device and distinguish between different
> > > > sensors.
> > > >   3) modify read temperature and initialization function.
> > >
> > > This comment doesn't mention the devm change. If it had it would
> > > have
> > > raised immediate alarm bells.
> > >
> > > I'm also not keen on the web of pointers that this driver is
> > > steadily
> > > evolving.  I can't immediately see how to reduce that complexity
> > > however.
> >
> > So I might be responsible for that, and looking back, this has been a
> > mistake.
> >
> > This driver was initally put together to support a controller found
> > in
> > older (A10 up to A31) Allwinner SoCs. This controller had an ADC
> > driver that could be operated as a touchscreen controller, and was
> > providing a CPU temperature sensor and a general purpose ADC.
> >
> > However, we already had a driver for that controller in drivers/input
> > to report the CPU temperature, and the one in IIO was introduced to
> > support the general purpose ADC (and the CPU temperature). The long
> > term goal was to add the touchscreen feature as well eventually so
> > that we could remove the one in drivers/input. That didn't happen.
> >
> > At the same time, the Allwinner hardware slowly evolved to remove the
> > touchscreen and ADC features, and only keep the CPU temperature
> > readout. It then evolved further on to support multiple temperatures
> > (for different clusters, the GPU, and so on).
> >
> > So, today, we're in a situation where I was pushing everything into
> > that IIO drivers since there was similiraties between all the
> > generations, but the fact that we have to support so many odd cases
> > (DT bindings compatibility, controllers with and without ADC, etc)
> > that it becomes a real mess.
> >
> > And that mess isn't really used by anybody, since we want to have the
> > touchscreen.
> >
> > There's only one SoC that is supported only by that driver, which is
> > the A33 that only had a CPU temperature readout, and is still pretty
> > similar to the latest SoC from Allwinner (that is supported by this
> > series).
> >
> > I guess, for everyone's sanity and in order to not stall this
> > further,
> > it would just be better to create an hwmon driver for the A33 (and
> > onwards, including the H6) for the SoC that just have the temperature
> > readout feature. And for the older SoC, we just keep the older driver
> > under input/. Once the A33 is supported, we'll remove the driver in
> > IIO (and the related bits in drivers/mfd).

a hwmon driver or a thermal driver?

>
> I think a thermal driver is better.

This is what I hope to see a few months ago.

>
> Other SoCs' thermal sensor drivers are all thermal drivers.
>
> >
> > Armbian already has a driver for that they never upstreamed iirc, so
> > it might be a good starting point, and we would add the support for
> > the H6. How does that sound?
>
> I think the developer abandoned to upstream it because of the previous
> problem ;-)
>
> Maybe it can be taken and add A33&H6 support.

If OK, I am going to start some thermal driver work this weekend.  : )

Cheers,
Yangtao

>
> >
> > Sorry for wasting everybody's time on this.
> >
> > Maxime
> >
> > --
> > Maxime Ripard, Bootlin
> > Embedded Linux and Kernel engineering
> > https://bootlin.com
> > _______________________________________________
> > linux-arm-kernel mailing list
> > linux-arm-kernel@lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>

  reply	other threads:[~2019-05-06 17:08 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-03  7:28 [PATCH 0/7] Add support for H6 " Yangtao Li
2019-05-03  7:28 ` [PATCH 1/7] iio: adc: sun4i-gpadc: rework for support multiple " Yangtao Li
2019-05-05 15:22   ` Jonathan Cameron
2019-05-06 12:28     ` Maxime Ripard
2019-05-06 16:52       ` Icenowy Zheng
2019-05-06 17:08         ` Frank Lee [this message]
2019-05-06 17:55           ` Ondřej Jirman
2019-05-07 13:59             ` Maxime Ripard
2019-05-03  7:28 ` [PATCH 2/7] iio: adc: sun4i-gpadc: introduce temp_data in gpadc_data Yangtao Li
2019-05-03  7:28 ` [PATCH 3/7] iio: adc: sun4i-gpadc: introduce gpadc_enable and gpadc_disable " Yangtao Li
2019-05-03  7:28 ` [PATCH 4/7] iio: adc: sun4i-gpadc-iio: support clocks and reset Yangtao Li
2019-05-03  7:28 ` [PATCH 5/7] dt-bindings: mfd: Add H6 GPADC binding Yangtao Li
2019-05-08 11:44   ` Lee Jones
2019-05-03  7:28 ` [PATCH 6/7] iio: adc: sun4i-gpadc-iio: add support for H6 thermal sensor Yangtao Li
2019-05-05 15:25   ` Jonathan Cameron
2019-05-08 11:45   ` Lee Jones
2019-05-03  7:28 ` [PATCH 7/7] iio: adc: sun4i-gpadc-iio convert to SPDX license tags Yangtao Li
2019-05-03  9:18   ` Maxime Ripard

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