531860e12d
Profiling has shown that ida_alloc_range() accounts for about 10% of the time spent in spi_sync() when using the AXI SPI Engine controller. This call is used to create a unique id for each SPI message to match to an IRQ when the message is complete. Since the core SPI code serializes messages in a message queue, we can only have one message in flight at a time, namely host->cur_msg. This means that we can use a fixed value instead of a unique id for each message since there can never be more than one message pending at a time. This patch removes the use of ida for the sync id and replaces it with a constant value. This simplifies the driver and improves performance. Reviewed-by: Nuno Sa <nuno.sa@analog.com> Signed-off-by: David Lechner <dlechner@baylibre.com> Link: https://lore.kernel.org/r/20240207-axi-spi-engine-round-2-1-v2-1-40c0b4e85352@baylibre.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.