tree 302ece15c574dc061b1dea4e67125c7b01342154
parent e81f3d81e282a156b47c1c2c09a1976e34073060
author Andy Lutomirski <luto@amacapital.net> 1368489520 +0000
committer Dave Airlie <airlied@redhat.com> 1369969372 +1000

Add arch_phys_wc_{add, del} to manipulate WC MTRRs if needed

Several drivers currently use mtrr_add through various #ifdef guards
and/or drm wrappers.  The vast majority of them want to add WC MTRRs
on x86 systems and don't actually need the MTRR if PAT (i.e.
ioremap_wc, etc) are working.

arch_phys_wc_add and arch_phys_wc_del are new functions, available
on all architectures and configurations, that add WC MTRRs on x86 if
needed (and handle errors) and do nothing at all otherwise.  They're
also easier to use than mtrr_add and mtrr_del, so the call sites can
be simplified.

As an added benefit, this will avoid wasting MTRRs and possibly
warning pointlessly on PAT-supporting systems.

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>