[RFC/PATCH v2 0/8] Clean up write-combining MTRR addition

[Andy Lutomirski <luto@amacapital.net>]

A fair number of drivers (mostly graphics) add write-combining MTRRs.
Most ignore errors and most add the MTRR even on PAT systems which don't
need to use MTRRs.

This series adds new functions arch_phys_wc_{add,del} that, on PAT-less
x86 systems with MTRRs, add MTRRs and report errors, and that do nothing
otherwise.  (Other architectures, if any, with a similar mechanism could
implement them.)

I've only tested the radeon driver, since I don't have test hardware
easily available for the other drivers.

Benefits include:
 - Simpler code
 - No more complaints about MTRR conflict warnings on PAT systems
 - Eventual unexporting of the MTRR API?

This series eliminates about half of the mtrr_add calls in drivers/.

Changes from v1:
 - Helpers renamed
 - Lots of bugs fixed

The series is also at:
https://git.kernel.org/cgit/linux/kernel/git/luto/linux.git/log/?h=mtrr_cleanup/rfc_v2

Andy Lutomirski (8):
  Add arch_phys_wc_{add,del} to manipulate WC MTRRs if needed
  drm (ast,cirrus,mgag200,nouveau,savage,vmwgfx): Remove
    drm_mtrr_{add,del}
  drm: Update drm_addmap and drm_mmap to use PAT WC instead of MTRRs
  drm,agpgart: Use pgprot_writecombine for AGP maps and make the MTRR
    optional
  i915: Use arch_phys_wc_{add,del}
  radeon: Switch to arch_phys_wc_add and add a missing ..._del
  uvesafb: Clean up MTRR code
  drm: Remove mtrr_add and mtrr_del fallback hack for non-MTRR systems

 Documentation/fb/uvesafb.txt           | 16 +++-----
 arch/x86/include/asm/io.h              |  7 ++++
 arch/x86/include/asm/mtrr.h            |  5 ++-
 arch/x86/kernel/cpu/mtrr/main.c        | 48 +++++++++++++++++++++++
 drivers/char/agp/frontend.c            |  8 ++--
 drivers/gpu/drm/ast/ast_ttm.c          | 13 ++-----
 drivers/gpu/drm/cirrus/cirrus_ttm.c    | 15 ++------
 drivers/gpu/drm/drm_bufs.c             | 17 +++++----
 drivers/gpu/drm/drm_pci.c              |  8 ++--
 drivers/gpu/drm/drm_stub.c             | 10 +----
 drivers/gpu/drm/drm_vm.c               | 22 +++++------
 drivers/gpu/drm/i915/i915_dma.c        | 44 +++------------------
 drivers/gpu/drm/mgag200/mgag200_ttm.c  | 14 ++-----
 drivers/gpu/drm/nouveau/nouveau_ttm.c  | 13 ++-----
 drivers/gpu/drm/radeon/radeon_object.c |  5 ++-
 drivers/gpu/drm/savage/savage_bci.c    | 43 ++++++++-------------
 drivers/gpu/drm/savage/savage_drv.h    |  5 +--
 drivers/gpu/drm/vmwgfx/vmwgfx_drv.c    | 10 ++---
 drivers/video/uvesafb.c                | 70 +++++++++-------------------------
 include/drm/drmP.h                     | 34 +----------------
 include/drm/drm_os_linux.h             | 16 --------
 include/linux/io.h                     | 25 ++++++++++++
 include/video/uvesafb.h                |  1 +
 23 files changed, 181 insertions(+), 268 deletions(-)

-- 
1.8.1.4