drm: Permit video-buffers writecombine mapping for MIPS
Since commit 4b050ba7 ("MIPS: pgtable.h: Implement the pgprot_writecombine function for MIPS") and commit c4687b15 ("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
Showing
Please register or sign in to comment