mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2026-05-05 21:44:23 -04:00
01862d01cb
Both the Lenovo Yoga Tablet 2 830 and 1050 models use an TI LP8557 LED backlight controller. On the 1050 the LP8557's PWM input is connected to the PMIC's PWM output and everything works fine with the defaults programmed into the LP8557 by the BIOS. But on the 830 the LP8557's PWM input is connected to a PWM output coming from the LCD panel's controller. The Android code has a hack in the i915 driver to write the non-standard DSI reg 0x9f with the desired backlight level to set the duty-cycle of the LCD's PWM output. To avoid having to have a similar hack in the mainline kernel the LP8557 entry in lenovo_yoga_tab2_830_1050_i2c_clients instead just programs the LP8557 to directly set the level, ignoring the PWM input. So far we have only been instantiating the LP8557 i2c_client for direct backlight control on the 830 model. But we want hide/disable the intel_backlight interface on the 830 model to avoid having 2 backlight interfaces for the same LCD panel. And the 830 and 1050 share the same DMI strings. So this will hide the intel_backlight interface on the 1050 model too. To avoid this causing problems make the backlight handling consistent between the 2 models and always directly use the LP8557. This also simplifies the code. Signed-off-by: Hans de Goede <hdegoede@redhat.com> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com> Link: https://lore.kernel.org/r/20230401150737.597417-1-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 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.