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8a08e50cee
Since commit4b050ba7a6("MIPS: pgtable.h: Implement the pgprot_writecombine function for MIPS") and commitc4687b15a8("MIPS: Fix definition of pgprot_writecombine()") write-combine vma mapping is available to be used by kernel subsystems for MIPS. In particular the uncached accelerated attribute is requested to be set by ioremap_wc() method and by generic PCI memory pages/ranges mapping methods. The same is done by the drm_io_prot()/ttm_io_prot() functions in case if write-combine flag is set for vma's passed for mapping. But for some reason the pgprot_writecombine() method calling is ifdefed to be a platform-specific with MIPS system being marked as lacking of one. At the very least it doesn't reflect the current MIPS platform implementation. So in order to improve the DRM subsystem performance on MIPS with UCA mapping enabled, we need to have pgprot_writecombine() called for buffers, which need store operations being combined. In case if particular MIPS chip doesn't support the UCA attribute, the mapping will fall back to noncached. Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Paul Burton <paul.burton@mips.com> Cc: James Hogan <jhogan@kernel.org> Acked-by: Christian König <christian.koenig@amd.com> Reviewed-by: Paul Burton <paul.burton@mips.com> Signed-off-by: Vadim V. Vlasov <vadim.vlasov@t-platforms.ru> Signed-off-by: Serge Semin <fancer.lancer@gmail.com> Signed-off-by: Sean Paul <seanpaul@chromium.org> Link: https://patchwork.freedesktop.org/patch/msgid/20190423123122.32573-1-fancer.lancer@gmail.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.