mirror of
https://github.com/hardkernel/linux.git
synced 2026-06-08 11:50:43 +09:00
ede033e1e8
This commit extends the flags that can be used in GPIO specifiers to indicate if a pull-up resistor or pull-down resistor should be enabled. While some pinctrl DT bindings already offer the capability of configuring pull-up/pull-down resistors at the pin level, a number of simple GPIO controllers don't have any pinmuxing capability, and therefore do not rely on the pinctrl DT bindings. Such simple GPIO controllers however sometimes allow to configure pull-up and pull-down resistors on a per-pin basis, and whether such resistors should be enabled or not is a highly board-specific HW characteristic. By using two additional bits of the GPIO flag specifier, we can easily allow the Device Tree to describe which GPIOs should have their pull-up or pull-down resistors enabled. Even though the two options are mutually exclusive, we still need two bits to encode at least three states: no pull-up/pull-down, pull-up, pull-down. Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com> Signed-off-by: Linus Walleij <linus.walleij@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.