From mboxrd@z Thu Jan 1 00:00:00 1970 From: Icenowy Zheng Subject: Re: [PATCH 1/7] iio: adc: sun4i-gpadc: rework for support multiple thermal sensor Date: Tue, 07 May 2019 00:52:22 +0800 Message-ID: <282ccf0979e6c58effd0e177917bdf824c32f64e.camel@aosc.io> References: <20190503072813.2719-1-tiny.windzz@gmail.com> <20190503072813.2719-2-tiny.windzz@gmail.com> <20190505162215.3594f77d@archlinux> <20190506122807.4u323iys74jddcet@flea> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20190506122807.4u323iys74jddcet@flea> Sender: linux-kernel-owner@vger.kernel.org To: Maxime Ripard , Jonathan Cameron Cc: mark.rutland@arm.com, devicetree@vger.kernel.org, lars@metafoo.de, Yangtao Li , linux-kernel@vger.kernel.org, linux-iio@vger.kernel.org, wens@csie.org, robh+dt@kernel.org, pmeerw@pmeerw.net, knaack.h@gmx.de, lee.jones@linaro.org, linux-arm-kernel@lists.infradead.org List-Id: devicetree@vger.kernel.org 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 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). I think a thermal driver is better. 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. > > 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