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Currently the imx_sc driver is reimplementing part of the thermal zone parsing from the thermal OF tree code to get the sensor id associated with a thermal zone sensor. The driver platform specific code should know what sensor is present and not rely on the thermal zone description to do a discovery. Well that is arguable but all the other drivers have a per platform data telling what sensor id to use. The imx_sc thermal driver is the only one using a different approach. Not invalid but forcing to keep a specific function 'thermal_zone_of_get_sensor_id()' to get the sensor id for a specific thermal zone as the self-explanatory function tells and having device tree code inside the driver. The thermal OF code had a rework and remains now self-encapsulated with a register/unregister functions and their 'devm' variants, except for the function mentioned above. After investigating, it appears the imx_sc sensor is defined in arch/arm64/boot/dts/freescale/imx8qxp.dtsi: which defines the cpu-thermal zone with the id: IMX_SC_R_SYSTEM This dtsi is included by: - imx8qxp-ai_ml.dts - imx8qxp-colibri.dtsi - imx8qxp-mek.dts The two first ones do not define more thermal zones The third one adds the pmic-thermal0 zone with id: IMX_SC_R_PMIC_0 The thermal OF code returns -ENODEV if the thermal zone registration with a specific id fails because the description is not available in the DT for such a sensor id. In this case we continue with the other ids without bailing out with an error. So we can build for the 'fsl,imx-sc-thermal' a compatible data, an array of sensor ids containing IMX_SC_R_SYSTEM and IMX_SC_R_PMIC_0. The latter won't be found but that will not result in an error but a normal case where we continue the initialization with other ids. Just to clarify, it is what the thermal framework does and what the other drivers are expecting: when a registration fails with -ENODEV this is not an error but a case where the description is not found in the device tree, that be can the entire thermal zones description or a specific thermal zone with an unknown id. There is one small functional change but without impact. When there is no 'thermal-zones' description the probe function was returning '-ENODEV', now it returns zero. When a thermal zone fails to register with an error different from '-ENODEV', the error is detected and returned. Change the code accordingly and remove the OF code from the driver. Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org> Link: https://lore.kernel.org/r/20220818082316.2717095-1-daniel.lezcano@linaro.org
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.