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Eric Anholt authored
In the absence of PAT, PAGE_KERNEL_WC ends up mapping to a memory type that
gets UC behavior even in the presence of a WC MTRR covering the area in
question.  By swapping to PAGE_KERNEL_UC_MINUS, we can get the actual
behavior the caller wanted (WC if you can manage it, UC otherwise).

This recovers the 40% performance improvement of using WC in the DRM
to upload vertex data.

Signed-off-by: default avatarEric Anholt <eric@anholt.net>
Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
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