From: "Ondřej Jirman" <megous@megous.com>
To: Maxime Ripard <maxime.ripard@bootlin.com>
Cc: Frank Lee <tiny.windzz@gmail.com>,
Mark Rutland <mark.rutland@arm.com>,
Daniel Lezcano <daniel.lezcano@linaro.org>,
catalin.marinas@arm.com, will.deacon@arm.com,
bjorn.andersson@linaro.org,
Mauro Carvalho Chehab <mchehab+samsung@kernel.org>,
paulmck@linux.ibm.com, stefan.wahren@i2se.com,
Linux PM <linux-pm@vger.kernel.org>, Chen-Yu Tsai <wens@csie.org>,
Jagan Teki <jagan@amarulasolutions.com>,
Andy Gross <andy.gross@linaro.org>,
rui.zhang@intel.com, devicetree@vger.kernel.org,
marc.w.gonzalez@free.fr, Eduardo Valentin <edubezval@gmail.com>,
enric.balletbo@collabora.com, robh+dt@kernel.org,
Jonathan.Cameron@huawei.com,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
olof@lixom.net, David Miller <davem@davemloft.net>
Subject: Re: [PATCH 2/3] thermal: sun50i: add thermal driver for h6
Date: Tue, 21 May 2019 12:27:21 +0200 [thread overview]
Message-ID: <20190521102721.5hgks6guzlhubj6d@core.my.home> (raw)
In-Reply-To: <20190521080515.qlni2lnmcwh7itl7@flea>
Hi Maxime,
On Tue, May 21, 2019 at 10:05:15AM +0200, Maxime Ripard wrote:
> On Sat, May 18, 2019 at 01:27:39AM +0800, Frank Lee wrote:
> > On Fri, May 17, 2019 at 3:36 PM Maxime Ripard <maxime.ripard@bootlin.com> wrote:
> > >
> > > On Fri, May 17, 2019 at 01:51:56AM +0800, Frank Lee wrote:
> > > > > > +struct sun50i_thermal_chip {
> > > > > > + int sensor_num;
> > > > > > + int offset;
> > > > > > + int scale;
> > > > > > + int ft_deviation;
> > > > > > + int temp_calib_base;
> > > > > > + int temp_data_base;
> > > > > > + int (*enable)(struct tsens_device *tmdev);
> > > > > > + int (*disable)(struct tsens_device *tmdev);
> > > > > > +};
> > > > >
> > > > > I'm not super fond of having a lot of quirks that are not needed. If
> > > > > we ever need those quirks when adding support for a new SoC, then
> > > > > yeah, we should totally have some, but only when and if it's needed.
> > > > >
> > > > > Otherwise, the driver is more complicated for no particular reason.
> > > >
> > > > This is unavoidable because of the difference in soc.
> > >
> > > I know, but this isn't my point.
> > >
> > > My point is that at this time of the driver development, we don't know
> > > what is going to be needed to support all of those SoCs.
> > >
> > > Some of the parameters you added might not be needed, some parameters
> > > might be missing, we don't know. So let's keep it simple for now.
> > >
> > > > > > +static int tsens_probe(struct platform_device *pdev)
> > > > > > +{
> > > > > > + struct tsens_device *tmdev;
> > > > > > + struct device *dev = &pdev->dev;
> > > > > > + int ret;
> > > > > > +
> > > > > > + tmdev = devm_kzalloc(dev, sizeof(*tmdev), GFP_KERNEL);
> > > > > > + if (!tmdev)
> > > > > > + return -ENOMEM;
> > > > > > +
> > > > > > + tmdev->dev = dev;
> > > > > > + tmdev->chip = of_device_get_match_data(&pdev->dev);
> > > > > > + if (!tmdev->chip)
> > > > > > + return -EINVAL;
> > > > > > +
> > > > > > + ret = tsens_init(tmdev);
> > > > > > + if (ret)
> > > > > > + return ret;
> > > > > > +
> > > > > > + ret = tsens_register(tmdev);
> > > > > > + if (ret)
> > > > > > + return ret;
> > > > > > +
> > > > > > + ret = tmdev->chip->enable(tmdev);
> > > > > > + if (ret)
> > > > > > + return ret;
> > > > > >
> > > > > > + platform_set_drvdata(pdev, tmdev);
> > > > >
> > > > > Your registration should be the very last thing you do. Otherwise, you
> > > > > have a small window where the get_temp callback can be called, but the
> > > > > driver will not be functional yet.
> > > >
> > > > No. Anyway, ths data qcquisition is ms level.
> > >
> > > That's kind of irrelevant. There's nothing preventing get_temp to be
> > > called right away.
> >
> > As Ondřej said,
> >
> > Registration after enabling will lead to call tz update on non-registered tz
> > from an interrupt handler.
>
> I'm probably missing something but you're not using the interrupts, so
> how could an interrupt handler call it?
>
> Also, other drivers seem to be doing that just fine (mtk_thermal for
> example), so surely there's a way?
Last version is using the interrupts.
Drivers do it in various ways. For example imx_thermal (and others like
hisi_thermal) does it the suggested way. It enables interrupts after thermal
zone registration, so that IRQ handler doesn't get invoked before the tzd is
registered.
regards,
o.
> > > > > > + ret = tsens_calibrate(tmdev);
> > > > > > + if (ret)
> > > > > > + return ret;
> > > > > > +
> > > > > > + /*
> > > > > > + * clkin = 24MHz
> > > > > > + * T acquire = clkin / (SUN50I_THS_CTRL0_T_ACQ + 1)
> > > > > > + * = 20us
> > > > > > + */
> > > > > > + regmap_write(tmdev->regmap, SUN50I_THS_CTRL0,
> > > > > > + SUN50I_THS_CTRL0_T_ACQ(479));
> > > > > > + /* average over 4 samples */
> > > > > > + regmap_write(tmdev->regmap, SUN50I_H6_THS_MFC,
> > > > > > + SUN50I_THS_FILTER_EN |
> > > > > > + SUN50I_THS_FILTER_TYPE(1));
> > > > > > + /* period = (SUN50I_H6_THS_PC_TEMP_PERIOD + 1) * 4096 / clkin; ~10ms */
> > > > > > + regmap_write(tmdev->regmap, SUN50I_H6_THS_PC,
> > > > > > + SUN50I_H6_THS_PC_TEMP_PERIOD(58));
> > > > > > + /* enable sensor */
> > > > > > + val = GENMASK(tmdev->chip->sensor_num - 1, 0);
> > > > > > + regmap_write(tmdev->regmap, SUN50I_H6_THS_ENABLE, val);
> > > > > > +
> > > > > > + return 0;
> > > > > > +
> > > > > > +assert_reset:
> > > > > > + reset_control_assert(tmdev->reset);
> > > > > > +
> > > > > > + return ret;
> > > > >
> > > > > Can't we do that with runtime_pm?
> > > >
> > > > Saving energy doesn't make much sense compared to system security.
> > >
> > > I'm not sure what you mean by security.
> >
> > Protect system hardware from damage.
>
> The point of runtime_pm is to keep the device on as long as it is
> used, so it wouldn't change anything there.
>
> I mean, you can even enable it in the probe if you want, my point is
> that the hooks that you have are exact equivalents to the one provided
> by runtime_pm already, so there's no need to define them in the first
> place.
>
> 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
next prev parent reply other threads:[~2019-05-21 10:27 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-12 8:26 [PATCH 0/3] add thermal driver for h6 Yangtao Li
2019-05-12 8:26 ` [PATCH 1/3] arm64: defconfig: add allwinner sid support Yangtao Li
2019-05-12 13:25 ` Maxime Ripard
2019-05-12 8:26 ` [PATCH 2/3] thermal: sun50i: add thermal driver for h6 Yangtao Li
2019-05-12 13:39 ` Maxime Ripard
2019-05-12 21:41 ` Ondřej Jirman
2019-05-16 15:02 ` Maxime Ripard
2019-05-16 17:36 ` Ondřej Jirman
2019-05-16 18:10 ` Frank Lee
2019-05-17 7:31 ` Maxime Ripard
2019-05-17 17:19 ` Frank Lee
2019-05-21 7:41 ` Maxime Ripard
2019-05-16 17:51 ` Frank Lee
2019-05-16 21:11 ` Ondřej Jirman
2019-05-17 7:36 ` Maxime Ripard
2019-05-17 17:27 ` Frank Lee
2019-05-21 8:05 ` Maxime Ripard
2019-05-21 10:27 ` Ondřej Jirman [this message]
2019-05-21 14:27 ` Maxime Ripard
2019-05-21 17:33 ` Ondřej Jirman
2019-05-17 19:21 ` Vasily Khoruzhick
2019-05-21 7:47 ` Maxime Ripard
2019-05-12 22:16 ` Ondřej Jirman
2019-05-16 18:06 ` Frank Lee
2019-05-16 18:29 ` Ondřej Jirman
2019-05-17 16:34 ` Frank Lee
2019-05-19 14:22 ` Ondřej Jirman
2019-05-20 10:59 ` Maxime Ripard
2019-05-25 18:48 ` Frank Lee
2019-05-25 18:51 ` Frank Lee
2019-05-25 19:53 ` Vasily Khoruzhick
2019-05-26 1:24 ` Ondřej Jirman
2019-05-12 22:39 ` Ondřej Jirman
2019-05-13 10:01 ` Maxime Ripard
2019-05-16 18:08 ` Frank Lee
2019-05-12 8:26 ` [PATCH 3/3] dt-bindings: thermal: add binding document for h6 thermal controller Yangtao Li
2019-05-12 13:41 ` Maxime Ripard
2019-05-16 18:13 ` Frank Lee
2019-05-17 7:38 ` Maxime Ripard
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