tree f7b04c2dad467cc072c774c7b7dbbd6d179f4eee
parent 5c0f6ee766d7c689e71a7df5e5fa87941affd75a
author Alex Williamson <alex.williamson@redhat.com> 1377704348 -0600
committer Daniel Vetter <daniel.vetter@ffwll.ch> 1378228679 +0200

i915: Update VGA arbiter support for newer devices

This is intended to add VGA arbiter support for Intel HD graphics on
Core processors.  The old GMCH registers no longer exist, so even
though it appears that i915 participates in VGA arbitration, it doesn't
work.  On Intel HD graphics we already attempt to disable VGA regions
of the device.  This makes registering as a VGA client unnecessary since
we don't intend to operate differently depending on how many VGA devices
are present.  We can disable VGA memory regions by clearing the memory
enable bit in the VGA MSR.  That only leaves VGA IO, which we update
the VGA arbiter to know that we don't participate in VGA memory
arbitration.  We also add a hook on unload to re-enable memory and
reinstate VGA memory arbitration.

v3: Use explicit LEGACY_IO | LEGACY_MEM when restoring rather than
    LEGACY_MASK, per Ville's comments.

v2: I915_READ/WRITE accessors don't work in i915_disable_vga, use inb/outb
    directly.  Also, on the driver unbind VGA enable path, acquire legacy
    IO to re-enable VGA memory.  Correct comment.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
[danvet: Add patch changelog. Also squash in a fixup to have a dummy
static inline for vga_set_legacy_decoding for CONFIG_VGA_ARB=n as
reported by the 0-day kernel build bot.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

fixup 2