From: "Ondřej Jirman" <megous@megous.com>
To: Maxime Ripard <maxime.ripard@bootlin.com>
Cc: mark.rutland@arm.com, Yangtao Li <tiny.windzz@gmail.com>,
catalin.marinas@arm.com, will.deacon@arm.com,
bjorn.andersson@linaro.org, marc.w.gonzalez@free.fr,
mchehab+samsung@kernel.org, paulmck@linux.ibm.com,
stefan.wahren@i2se.com, daniel.lezcano@linaro.org, wens@csie.org,
jagan@amarulasolutions.com, andy.gross@linaro.org,
rui.zhang@intel.com, devicetree@vger.kernel.org,
linux-pm@vger.kernel.org, edubezval@gmail.com, olof@lixom.net,
robh+dt@kernel.org, Jonathan.Cameron@huawei.com,
linux-arm-kernel@lists.infradead.org, gregkh@linuxfoundation.org,
linux-kernel@vger.kernel.org, enric.balletbo@collabora.com,
davem@davemloft.net
Subject: Re: [PATCH 2/3] thermal: sun50i: add thermal driver for h6
Date: Thu, 16 May 2019 19:36:49 +0200 [thread overview]
Message-ID: <20190516173649.5s2s32ol43kbbhzg@core.my.home> (raw)
In-Reply-To: <20190516150252.hf4u3bloo37chy6q@flea>
Hello Maxime,
On Thu, May 16, 2019 at 05:02:52PM +0200, Maxime Ripard wrote:
> Hi,
>
> On Sun, May 12, 2019 at 11:41:28PM +0200, Ondřej Jirman wrote:
> > > > +static int tsens_get_temp(void *data, int *temp)
> > > > +{
> > > > + struct tsensor *s = data;
> > > > + struct tsens_device *tmdev = s->tmdev;
> > > > + int val;
> > > > +
> > > > + regmap_read(tmdev->regmap, tmdev->chip->temp_data_base +
> > > > + 0x4 * s->id, &val);
> > > > +
> > > > + if (unlikely(val == 0))
> > > > + return -EBUSY;
> > >
> > > I'm not sure why a val equals to 0 would be associated with EBUSY?
> >
> > Thermal zone driver can (will) call get_temp before we got the
> > first interrupt and the thermal data. In that case val will be 0.
> >
> > Resulting in:
> >
> > (val + offset) * scale = (-2794) * -67 = 187198
> >
> > 187°C and immediate shutdown during boot - based on cirtical
> > temperature being reached.
> >
> > Busy here means, get_temp does not yet have data. Thermal zone
> > driver just reports any error to dmesg output.
>
> Ah, that makes sense.
>
> I guess if we're switching to an interrupt-based driver, then we can
> just use a waitqueue, or is get_temp supposed to be atomic?
I'm not entirely sure, because I might have inadverently used a combination of
interrupt and polling when testing this. It may be that if we set polling-delay
to 0 in dts, that tz core will not try to call get_temp prematurely at all, and
will simply wait for temperature update from the interrupt.
I guess this needs to be tested/checked in tz code.
regards,
o.
> 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
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next prev parent reply other threads:[~2019-05-16 17:37 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 [this message]
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
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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