99165b93da
In roc-rk3328-cc board, the signal voltage of sdmmc is supplied by the vcc_sdio regulator, which is a mux between 1.8V and 3.3V, controlled by a special output only gpio pin labeled "gpiomut_pmuio_iout", corresponding bit 1 of the syscon GRF_SOC_CON10. This special pin can now be reference as <&grf_gpio 0>, thanks to the gpio-syscon driver, which makes writing regulator-gpio possible. If the signal voltage changes, the io domain needs to change correspondingly. To use this feature, the following options are required in kernel config: - CONFIG_GPIO_SYSCON=y - CONFIG_POWER_AVS=y - CONFIG_ROCKCHIP_IODOMAIN=y Signed-off-by: Levin Du <djw@t-chip.com.cn> Signed-off-by: Heiko Stuebner <heiko@sntech.de>
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.
See Documentation/00-INDEX for a list of what is contained in each file.
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.