9ba7701852
[ Upstream commit de9850b5c606b754dd7861678d6e2874b96b04f8 ]
Setting up many of the registers for a new SPI transfer involves
unconditionally disabling the SPI controller, writing the register
value and re-enabling the controller. This is being done for registers
even when the value is unchanged and is also done for registers that
don't require the controller to be disabled for the change to take
effect. Make an effort to detect changes to the register values, and
only disables the controller if the new register value is different
and disabling the controller is required. This stops the controller
being repeated disabled and the bus going tristate before every
transfer.
Fixes: 9ac8d17694b6 ("spi: add support for microchip fpga spi controllers")
Signed-off-by: Steve Wilkins <steve.wilkins@raymarine.com>
Co-developed-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://patch.msgid.link/20240715-depict-twirl-7e592eeabaad@wendy
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@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.