47319c4b81
commit cc5f7e2fcbe396f2f461cd67c872af771a334bca upstream. On the SII9022, the IOVCC and CVCC12 supplies must reach the correct voltage before the reset sequence is initiated. On most boards, this assumption is true at boot-up, so initialization succeeds. However, when we try to initialize the chip with incorrect supply voltages, it will not respond to I2C requests. sii902x_probe() fails with -ENXIO. To resolve this, look for the "iovcc" and "cvcc12" regulators, and make sure they are enabled before starting the reset sequence. If these supplies are not available in devicetree, then they will default to dummy-regulator. In that case everything will work like before. This was observed on a STM32MP157C-DK2 booting in u-boot falcon mode. On this board, the supplies would be set by the second stage bootloader, which does not run in falcon mode. Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com> Signed-off-by: Sam Ravnborg <sam@ravnborg.org> [Fix checkpatch warnings] Link: https://patchwork.freedesktop.org/patch/msgid/20201020221501.260025-2-mr.nuke.me@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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.