Hans de Goede 607fbac0fc platform/x86: x86-android-tablets: Add backlight ctrl for Lenovo Yoga Tab 3 Pro YT3-X90F
The YT3 uses an TI LP8557 LED backlight controller, the LP8557's PWM input
is connected to a PWM output coming from the LCD panel's controller.

The Android kernel has a hack in the i915 driver to write the non-standard
DSI reg 0x51 with the desired level to set the duty-cycle of the LCD's PWM.

To avoid having to have a similar hack in the mainline kernel program
instantiate an i2c-client for the LP8557 with platform-data to have
the LP8557 to directly set the level (ignoring its PWM input), this allows
backlight brightness control through a backlight device registered by
the lp855x_bl driver.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20230301092331.7038-13-hdegoede@redhat.com
2023-03-07 12:08:31 +01:00
2023-03-05 10:49:37 -08:00
2022-09-28 09:02:20 +02:00
2023-03-05 14:52:03 -08:00

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.
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