Re: [PATCH v3 3/9] drm: Update drm_addmap and drm_mmap to use PAT WC instead of MTRRs

On Tue, May 14, 2013 at 9:58 AM, Andy Lutomirski luto@amacapital.net wrote:

Previously, DRM_FRAME_BUFFER mappings, as well as DRM_REGISTERS mappings with DRM_WRITE_COMBINING set, resulted in an unconditional MTRR being added but the actual mappings being created as UC-.

Now these mappings have the MTRR added only if needed, but they will be mapped with pgprot_writecombine.

The non-WC DRM_REGISTERS case now uses pgprot_noncached instead of hardcoding the bit twiddling.

The DRM_AGP case is unchanged for now.

Just FYI this breaks on powerpc build, I've fixed it up and pushed the fixed version to drm-next-staging, I'll push that to drm-next in a couple of days, once kbuild robot hits it.

Dave.