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Previously using dma_alloc_wc() API we created cache coherent (mapped as write-back) mappings. Because we disable MMU600 snooping it was required to do costly page walk and cache flushes after each page table modification. With write-combined buffers it's possible to do a single write memory barrier to flush write-combined buffer to memory which simplifies the driver and significantly reduce time of map/unmap operations. Mapping time of 255 MB is reduced from 2.5 ms to 500 us. Signed-off-by: Karol Wachowski <karol.wachowski@linux.intel.com> Reviewed-by: Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com> Reviewed-by: Jeffrey Hugo <quic_jhugo@quicinc.com> Signed-off-by: Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20231028155936.1183342-7-stanislaw.gruszka@linux.intel.com
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.