As a general principal, it is best to do as little as possible in an interrupt handler. This patch reworks the AXI SPI Engine driver to move timer_delete_sync() and spi_finalize_current_message() out of the interrupt handler. Instead, spi_finalize_current_message() is moved to the transfer_one_message function (similar to nearly all other SPI controllers). A completion is now used to wait for the sync interrupt that indicates that the message is complete. The watchdog timer is no longer needed since we can use the wait_for_completion_timeout() function to wait for the message to complete with the same effect. As a bonus, these changes also improve throughput of the SPI controller. For example, this was tested on a ZynqMP with a 80MHz SCLK reading 4 byte samples from an ADC. The max measured throughput increased from 26k to 28k samples per second. 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-v2-2-40c0b4e85352@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.
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