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In some cases SPI child devices behind spi-mux require different settings like: max_speed_hz, mode and bits_per_word. Typically the slave device driver puts the settings in place and calls spi_setup() once during probe and assumes they stay in place for all following spi transfers. However spi-mux forwarded spi_setup() -call to SPI master driver only when slave driver calls spi_setup(). If second slave device was accessed meanwhile and that driver called spi_setup(), the settings did not change back to the first spi device. In case of wrong max_speed_hz this caused spi trasfers to fail. This commit adds spi_setup() call after mux is changed. This way the right device specific parameters are set to the master driver. The fix has been tested by using custom hardware and debugging spi master driver speed settings. Co-authored-by: Petri Tauriainen <petri.tauriainen@bittium.com> Signed-off-by: Heikki Keranen <heikki.keranen@bittium.com> Link: https://lore.kernel.org/r/20240422114150.84426-1-heikki.keranen@bittium.com Signed-off-by: Mark Brown <broonie@kernel.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 reStructuredText 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.