From mboxrd@z Thu Jan 1 00:00:00 1970 From: Maxime Ripard Subject: Re: [PATCH 1/7] iio: adc: sun4i-gpadc: rework for support multiple thermal sensor Date: Tue, 7 May 2019 15:59:12 +0200 Message-ID: <20190507135912.4lev7ly2w4drlt7s@flea> References: <20190503072813.2719-1-tiny.windzz@gmail.com> <20190503072813.2719-2-tiny.windzz@gmail.com> <20190505162215.3594f77d@archlinux> <20190506122807.4u323iys74jddcet@flea> <282ccf0979e6c58effd0e177917bdf824c32f64e.camel@aosc.io> <20190506175525.swc5u7j6ntry7v3g@core.my.home> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="bydgprfj47ik7yub" Return-path: Content-Disposition: inline In-Reply-To: <20190506175525.swc5u7j6ntry7v3g@core.my.home> Sender: linux-kernel-owner@vger.kernel.org To: Frank Lee , Icenowy Zheng , Mark Rutland , devicetree@vger.kernel.org, lars@metafoo.de, Linux Kernel Mailing List , linux-iio@vger.kernel.org, Chen-Yu Tsai , robh+dt@kernel.org, Linux ARM , pmeerw@pmeerw.net, knaack.h@gmx.de, Lee Jones , Jonathan Cameron List-Id: devicetree@vger.kernel.org --bydgprfj47ik7yub Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, May 06, 2019 at 07:55:25PM +0200, Ond=C5=99ej Jirman wrote: > On Tue, May 07, 2019 at 01:08:39AM +0800, Frank Lee wrote: > > On Tue, May 7, 2019 at 12:52 AM Icenowy Zheng wrote: > > > > > > =E5=9C=A8 2019-05-06=E4=B8=80=E7=9A=84 14:28 +0200=EF=BC=8CMaxime Rip= ard=E5=86=99=E9=81=93=EF=BC=9A > > > > 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/inp= ut > > > > 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 t= he > > > > 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 t= he > > > > 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 temperatu= re > > > > readout feature. And for the older SoC, we just keep the older driv= er > > > > 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=EF=BC=9F > > > > > > > > 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. : ) > > There are plenty of thermal drivers flying around, with varying levels > of support for various SoCs: > > - H3/H5: https://megous.com/git/linux/commit/?h=3Dths-5.1&id=3Db8e20c5da7= a00b3a3fa1b274fc8d5bea95872b0a > - A83T: https://megous.com/git/linux/commit/?h=3Dths-5.1&id=3D796dff9a946= fd475cc1e4bb948a723ea841c640c > - H6: https://megous.com/git/linux/commit/?h=3Dopi3-5.1&id=3Daeab762c19b4= aa228a295258c9d6b2e1f143bf86 > > For H3/H5 Icenowy also tried to upstream some variant of my THS driver, w= ith > better SID/calibration data reading support. > > I'd suggest starting with the H6 driver above (as that implements the > calibration data readout correctly), and make it so that it can support m= ultiple > SoCs. Yeah, that seems like a good plan Maxime -- Maxime Ripard, Bootlin Embedded Linux and Kernel engineering https://bootlin.com --bydgprfj47ik7yub Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQRcEzekXsqa64kGDp7j7w1vZxhRxQUCXNGPMAAKCRDj7w1vZxhR xS2VAQDOVlzfYshYqB3RzzDSqFMZPH8If+sem/QedfMd4Lyj7AD+KkQ+2ms4+Ca9 JJceZmhL6UGhaXOTV4RQUMJQA+c6zgU= =DXHT -----END PGP SIGNATURE----- --bydgprfj47ik7yub--