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There's a bunch of overhead in spi-geni-qcom's prepare_message. Get rid of it. Before this change spi_geni_prepare_message() took around 14.5 us. After this change, spi_geni_prepare_message() takes about 1.75 us (as measured by ftrace). What's here: * We're always in FIFO mode, so no need to call it for every transfer. This avoids a whole ton of readl/writel calls. * We don't need to write a whole pile of config registers if the mode isn't changing. Cache the last mode and only do the work if needed. * For several registers we were trying to do read/modify/write, but there was no reason. The registers only have one thing in them, so just write them. Acked-by: Mark Brown <broonie@kernel.org> Reviewed-by: Akash Asthana <akashast@codeaurora.org> Signed-off-by: Douglas Anderson <dianders@chromium.org> Link: https://lore.kernel.org/r/20200701174506.3.I2b3d7aeb1ea622335482cce60c58d2f8381e61dd@changeid Signed-off-by: Bjorn Andersson <bjorn.andersson@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.