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: NAlex Williamson <alex.williamson@redhat.com>
Reviewed-by: NVille 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: NDaniel Vetter <daniel.vetter@ffwll.ch>

fixup 2

"Whether" is misspelled in various comments across the tree; this
fixes them. No code changes.
Signed-off-by: NAdam Buchbinder <adam.buchbinder@gmail.com>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

Add some stub functions for the case where CONFIG_VGA_ARB is disabled.
Signed-off-by: NMatthew Garrett <mjg@redhat.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Add some stub functions for the case where CONFIG_VGA_ARB is disabled.
Signed-off-by: NMatthew Garrett <mjg@redhat.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

The default VGA device is a somewhat fluid concept on platforms with
multiple GPUs. Add support for setting it so switching code can update
things appropriately, and make sure that the sysfs code returns the right
device if it's changed.

v2: Updated to fix builds when __ARCH_HAS_VGA_DEFAULT_DEVICE is false.
Signed-off-by: NMatthew Garrett <mjg@redhat.com>
Acked-by: NH. Peter Anvin <hpa@zytor.com>
Acked-by: benh@kernel.crashing.org
Cc: airlied@redhat.com
Signed-off-by: NDave Airlie <airlied@redhat.com>

Fix build warnings by providing a struct stub since no fields of
the struct are used:

include/linux/vgaarb.h:66:9: warning: 'struct pci_dev' declared inside parameter list
include/linux/vgaarb.h:66:9: warning: its scope is only this definition or declaration, which is probably not what you want
include/linux/vgaarb.h:99:34: warning: 'struct pci_dev' declared inside parameter list
include/linux/vgaarb.h:109:6: warning: 'struct pci_dev' declared inside parameter list
include/linux/vgaarb.h:121:8: warning: 'struct pci_dev' declared inside parameter list
include/linux/vgaarb.h:140:37: warning: 'struct pci_dev' declared inside parameter list
Signed-off-by: NRandy Dunlap <rdunlap@xenotime.net>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Fixes generated by 'codespell' and manually reviewed.
Signed-off-by: NLucas De Marchi <lucas.demarchi@profusion.mobi>

Fix link failure without the vga arbitrator.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NDave Airlie <airlied@redhat.com>

We don't actually need this include on any platform.

built on powerpc + x86, reported on m68k.
Reported-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: NDave Airlie <airlied@redhat.com>

vgaarb.h was missing the #define of the #ifndef at the top for the guard
to prevent multiple #include's from causing re-define errors
Signed-off-by: NDoug Goldstein <cardoe@gentoo.org>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Signed-off-by: NTiago Vignatti <tiago.vignatti@nokia.com>
Cc: Henry Zhao <Henry.Zhao@Sun.COM>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Fixes build when VGA_ARB is off.
Reported-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Remove reference to vgaarb.c and replace it with a comment about the
arbiter itself.
Reported-by: NTiago Vignatti <tiago.vignatti@nokia.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

Fix some warnings reported in linux-next + also cleanup some
comment errors noticed by Pekka Paalanen.
Signed-off-by: NDave Airlie <airlied@redhat.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

Background:
Graphic devices are accessed through ranges in I/O or memory space. While most
modern devices allow relocation of such ranges, some "Legacy" VGA devices
implemented on PCI will typically have the same "hard-decoded" addresses as
they did on ISA. For more details see "PCI Bus Binding to IEEE Std 1275-1994
Standard for Boot (Initialization Configuration) Firmware Revision 2.1"
Section 7, Legacy Devices.

The Resource Access Control (RAC) module inside the X server currently does
the task of arbitration when more than one legacy device co-exists on the same
machine. But the problem happens when these devices are trying to be accessed
by different userspace clients (e.g. two server in parallel). Their address
assignments conflict. Therefore an arbitration scheme _outside_ of the X
server is needed to control the sharing of these resources. This document
introduces the operation of the VGA arbiter implemented for Linux kernel.
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NTiago Vignatti <tiago.vignatti@nokia.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>