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635bdb7a3e
While the Hardware User Manual does not document the maximum time needed
for modifying bits in the MSIOF Control Register, experiments on R-Car
Gen2/Gen3 and SH-Mobile AG5 revealed the following typical modification
times for the various bits:
- CTR.TXE and CTR.RXE: no delay,
- CTR.TSCKE: less than 10 ns,
- CTR.TFSE: up to a few hundred ns (depending on SPI transfer clock,
i.e. less for faster transfers).
There are no reasons to believe these figures are different for
SH-MobileR2 SoCs (SH7723/SH7724).
Hence the minimum busy-looping delay of 10 µs is excessive.
Reduce the delay per loop iteration from 10 to 1 us, and the maximum
delay from 1000 to 100 µs.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
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 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.