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The Xiaomi [Mi]Pad 2 has 3 menu / home / back capacitive touch-buttons on its bottom bezel. These are backlit by LEDs attached to a TPS61158 LED controller which is controlled by the "pwm_soc_lpss_2" PWM output. Create a LED class device for this, using the new input-events trigger as default trigger so that the buttons automatically light up on any input activity. Note alternatively a "leds_pwm" platform device could be created together with the necessary fwnode_s_ and a fwnode link to the PWM controller. There are 2 downsides to this approach: 1. The code would still need to pwm_get() the PWM controller to get/attach a fwnode for the PWM controller fwnode link and setting up the necessary fwnodes is non-trivial. So this would likely require more code then simply registering the LED class device directly. 2. Currently the leds_pwm driver and its devicetree bindings do not support limiting the maximum dutycycle to less then 100% which is required in this case (the leds_pwm driver can probably be extended to allow this). Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Signed-off-by: Hans de Goede <hdegoede@redhat.com> Link: https://lore.kernel.org/r/20240509141207.63570-2-hdegoede@redhat.com
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 reStructuredText 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.