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From:   Jean-Baptiste Maneyrol <JManeyrol@invensense.com>
To:     Dmitry Osipenko <digetx@gmail.com>,
        Linus Walleij <linus.walleij@linaro.org>,
        Jonathan Cameron <jic23@kernel.org>,
        Lars-Peter Clausen <lars@metafoo.de>,
        Andy Shevchenko <andy.shevchenko@gmail.com>,
        Maxim Schwalm <maxim.schwalm@gmail.com>,
        Svyatoslav Ryhel <clamor95@gmail.com>
CC:     "linux-iio@vger.kernel.org" <linux-iio@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3] iio: gyro: mpu3050: Fix reported temperature value
Thread-Topic: [PATCH v3] iio: gyro: mpu3050: Fix reported temperature value
Thread-Index: AQHXN+XK9vVdDaBpkE6NR7jI8nyNw6rB2HVZ
Date:   Fri, 23 Apr 2021 10:14:13 +0000
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Hello,=0A=
=0A=
thanks for this work.=0A=
=0A=
Temperature value should obviously be 16 bits signed, thanks for the fix. B=
y looking at our internal datasheets, I can confirm the values for MPU-30x0=
 family (div by 280 and 23000 offset LSB).=0A=
=0A=
I'm sorry I don't have access to these more than 1 decade old chips, so I c=
annot test on my side. But there is no reason it wouldn't be OK.=0A=
=0A=
Acked-by: Jean-Baptiste Maneyrol <jmaneyrol@invensense.com>=0A=
=0A=
Thanks,=0A=
JB=0A=
=0A=
From: Dmitry Osipenko <digetx@gmail.com>=0A=
Sent: Friday, April 23, 2021 04:09=0A=
To: Linus Walleij <linus.walleij@linaro.org>; Jonathan Cameron <jic23@kerne=
l.org>; Lars-Peter Clausen <lars@metafoo.de>; Andy Shevchenko <andy.shevche=
nko@gmail.com>; Maxim Schwalm <maxim.schwalm@gmail.com>; Svyatoslav Ryhel <=
clamor95@gmail.com>=0A=
Cc: linux-iio@vger.kernel.org <linux-iio@vger.kernel.org>; linux-kernel@vge=
r.kernel.org <linux-kernel@vger.kernel.org>=0A=
Subject: [PATCH v3] iio: gyro: mpu3050: Fix reported temperature value =0A=
=A0=0A=
=A0CAUTION: This email originated from outside of the organization. Please =
make sure the sender is who they say they are and do not click links or ope=
n attachments unless you recognize the sender and know the content is safe.=
=0A=
=0A=
The raw temperature value is a 16-bit signed integer. The sign casting=0A=
is missing in the code, which results in a wrong temperature reported=0A=
by userspace tools, fix it.=0A=
=0A=
Cc: stable@vger.kernel.org=0A=
Fixes: 3904b28efb2c ("iio: gyro: Add driver for the MPU-3050 gyroscope")=0A=
Datasheet: https://urldefense.com/v3/__https://www.cdiweb.com/datasheets/in=
vensense/mpu-3000a.pdf__;!!As-oOPDlYaQ!RejqeP2WMYRtGXwerukURT11pBrLee8OdIBx=
dEPzcNdqyuOVrDeorUdlv7_pvdRarvk$ =0A=
Tested-by: Maxim Schwalm <maxim.schwalm@gmail.com> # Asus TF700T=0A=
Tested-by: Svyatoslav Ryhel <clamor95@gmail.com> # Asus TF201=0A=
Reported-by: Svyatoslav Ryhel <clamor95@gmail.com>=0A=
Reviewed-by: Andy Shevchenko <Andy.Shevchenko@gmail.com>=0A=
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>=0A=
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>=0A=
---=0A=
=0A=
v3: - Improved comment in the code, saying that the temperature range=0A=
=A0=A0=A0=A0=A0 corresponds to the "best fit straight line" range where tem=
perature=0A=
=A0=A0=A0=A0=A0 is reported reliably, i.e. in accordance to the linear equa=
tion.=0A=
=0A=
v2: - Replaced "signed 16bit integer" wording with "16-bit signed integer",=
=0A=
=A0=A0=A0=A0=A0 replaced "Link" tag with the "Datasheet" and added "Fixes" =
tag as was=0A=
=A0=A0=A0=A0=A0 suggested by Andy Shevchenko.=0A=
=0A=
=A0=A0=A0 - Added r-b from Andy Shevchenko and Linus Walleij.=0A=
=0A=
=A0drivers/iio/gyro/mpu3050-core.c | 13 +++++++++++--=0A=
=A01 file changed, 11 insertions(+), 2 deletions(-)=0A=
=0A=
diff --git a/drivers/iio/gyro/mpu3050-core.c b/drivers/iio/gyro/mpu3050-cor=
e.c=0A=
index ac90be03332a..f17a93519535 100644=0A=
--- a/drivers/iio/gyro/mpu3050-core.c=0A=
+++ b/drivers/iio/gyro/mpu3050-core.c=0A=
@@ -272,7 +272,16 @@ static int mpu3050_read_raw(struct iio_dev *indio_dev,=
=0A=
=A0=A0=A0=A0=A0=A0=A0=A0 case IIO_CHAN_INFO_OFFSET:=0A=
=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 switch (chan->type) {=0A=
=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 case IIO_TEMP:=0A=
-=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 /* The =
temperature scaling is (x+23000)/280 Celsius */=0A=
+=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 /*=0A=
+=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 * Th=
e temperature scaling is (x+23000)/280 Celsius=0A=
+=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 * fo=
r the "best fit straight line" temperature range=0A=
+=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 * of=
 -30C..85C.=A0 The 23000 includes room temperature=0A=
+=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 * of=
fset of +35C, 280 is the precision scale and x is=0A=
+=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 * th=
e 16-bit signed integer reported by hardware.=0A=
+=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 *=0A=
+=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 * Te=
mperature value itself represents temperature of=0A=
+=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 * th=
e sensor die.=0A=
+=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 */=
=0A=
=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 *v=
al =3D 23000;=0A=
=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 re=
turn IIO_VAL_INT;=0A=
=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 default:=0A=
@@ -329,7 +338,7 @@ static int mpu3050_read_raw(struct iio_dev *indio_dev,=
=0A=
=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=
=A0=A0=A0=A0=A0=A0=A0 goto out_read_raw_unlock;=0A=
=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 }=
=0A=
=A0=0A=
-=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 *val =
=3D be16_to_cpu(raw_val);=0A=
+=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 *val =
=3D (s16)be16_to_cpu(raw_val);=0A=
=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 re=
t =3D IIO_VAL_INT;=0A=
=A0=0A=
=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 go=
to out_read_raw_unlock;=0A=
-- =0A=
2.30.2=0A=