7dba2adb06
In the AXI SPI Engine driver, compiling the message is an expensive operation. Previously, it was done per message transfer in the prepare_message hook. This patch moves the message compile to the optimize_message hook so that it is only done once per message in cases where the peripheral driver calls spi_optimize_message(). This can be a significant performance improvement for some peripherals. For example, the ad7380 driver saw a 13% improvement in throughput when using the AXI SPI Engine driver with this patch. Since we now need two message states, one for the optimization stage that doesn't change for the lifetime of the message and one that is reset on each transfer for managing the current transfer state, the old msg->state is split into msg->opt_state and spi_engine->msg_state. The latter is included in the driver struct now since there is only one current message at a time that can ever use it and it is in a hot path so avoiding allocating a new one on each message transfer saves a few cpu cycles and lets us get rid of the prepare_message callback. Signed-off-by: David Lechner <dlechner@baylibre.com> Link: https://msgid.link/r/20240219-mainline-spi-precook-message-v2-4-4a762c6701b9@baylibre.com Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.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 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.