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| author | Jakob Hauser <jahau@rocketmail.com> | 2022-09-04 23:49:35 +0200 |
|---|---|---|
| committer | Bjorn Andersson <andersson@kernel.org> | 2022-09-06 09:55:31 -0500 |
| commit | 3ae82f22ed7a746a8a9e89ea840401c46deddbb3 (patch) | |
| tree | 7e6e08d3fcbfe152b01c3dd5ec0c43c872a463b9 /security | |
| parent | 7dac7991408f77b0b33ee5e6b729baa683889277 (diff) | |
| download | linux-3ae82f22ed7a746a8a9e89ea840401c46deddbb3.tar.bz2 | |
arm64: dts: qcom: msm8916-samsung-serranove: Add magnetometer
Add magnetometer Yamaha YAS537 to the DeviceTree of samsung-serranove.
The YAS537 variant was recently added to the Yamaha YAS magnetometers
driver [1].
In the DeviceTree of samsung-serranove for the Android kernel, there is
unfortunately no information on interrupts or pinctrl [2].
In the Android kernel driver for magnetometer Yamaha YAS537, there is a
device-specific matrix to correct an ellipsoid shape of the measure values
into a sphere shape [3]. This could be converted and applied to a mount-matrix.
However, the current state of the mainline Yamaha YAS537 driver needs
post-process calibration in userspace anyway, as it lacks a formula to center
the measure values around zero. The correction of the ellipsoid into a sphere
can be done in the post-process calibration as well.
A mount-matrix is needed nonetheless. When putting samsung-serranove flat on
a table in portrait orientation heading north, the Yamaha YAS537 magnetometer
axes natively point X+ to north, Y+ to east and Z+ into the ground, which
corresponds to a common way to define the Earth's magnetic field coordinate
system [4]. According to the IIO definition, it should be Y+ to north, X+ to
east and Z+ upwards [5], which corresponds to a common device coordinate system
and eases sensor fusing.
[1] https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/drivers/iio/magnetometer/yamaha-yas530.c?id=65f79b501030678393eae0ae03d60a8151fbef55
[2] https://github.com/msm8916-mainline/android_kernel_qcom_msm8916/blob/GT-I9195I/arch/arm/boot/dts/samsung/msm8916/msm8916-sec-serranovelte-eur-r03.dtsi#L318-L321
[3] https://github.com/msm8916-mainline/android_kernel_qcom_msm8916/blob/GT-I9195I/drivers/iio/magnetometer/yas_mag_drv-yas537.c#L105-L106
[4] https://en.wikipedia.org/wiki/Earth%27s_magnetic_field#Characteristics
[5] https://github.com/torvalds/linux/blob/v5.19/Documentation/devicetree/bindings/iio/mount-matrix.txt#L93-L126
Cc: Stephan Gerhold <stephan@gerhold.net>
Signed-off-by: Jakob Hauser <jahau@rocketmail.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20220904214935.31032-1-jahau@rocketmail.com
Diffstat (limited to 'security')
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