PCI/VGA: Fix typos

Fix typos, rewrap to fill 78 columns, convert to conventional multi-line
style.

[bhelgaas: squash and add more fixes]
Link: https://lore.kernel.org/r/20230808223412.1743176-7-sui.jingfeng@linux.dev
Link: https://lore.kernel.org/r/20230808223412.1743176-9-sui.jingfeng@linux.dev
Link: https://lore.kernel.org/r/20230808223412.1743176-10-sui.jingfeng@linux.dev
Link: https://lore.kernel.org/r/20230808223412.1743176-11-sui.jingfeng@linux.dev
Signed-off-by: Sui Jingfeng <suijingfeng@loongson.cn>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

PCI/VGA: Replace full MIT license text with SPDX identifier

Per Documentation/process/license-rules.rst, the SPDX MIT identifier is
equivalent to including the entire MIT license text from
LICENSES/preferred/MIT.

Replace the MIT license text with the equivalent SPDX identifier.

Link: https://lore.kernel.org/r/20230808223412.1743176-12-sui.jingfeng@linux.dev
Signed-off-by: Sui Jingfeng <suijingfeng@loongson.cn>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>

vgaarb: don't pass a cookie to vga_client_register

The VGA arbitration is entirely based on pci_dev structures, so just pass
that back to the set_vga_decode callback.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20210716061634.2446357-8-hch@lst.de
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Christian König <christian.koenig@amd.com>

vgaarb: remove the unused irq_set_state argument to vga_client_register

All callers pass NULL as the irq_set_state argument, so remove it and
the ->irq_set_state member in struct vga_device.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20210716061634.2446357-7-hch@lst.de
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Christian König <christian.koenig@amd.com>

vgaarb: provide a vga_client_unregister wrapper

Add a trivial wrapper for the unregister case that sets all fields to
NULL.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20210716061634.2446357-6-hch@lst.de
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Christian König <christian.koenig@amd.com>

vgaarb: cleanup vgaarb.h

Merge the different CONFIG_VGA_ARB ifdef blocks, remove superflous
externs, and regularize the stubs for !CONFIG_VGA_ARB.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20210716061634.2446357-5-hch@lst.de
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Christian König <christian.koenig@amd.com>

vgaarb: move the kerneldoc for vga_set_legacy_decoding to vgaarb.c

Kerneldoc comments should be at the implementation side, not in the
header just declaring the prototype.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20210716061634.2446357-4-hch@lst.de
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Christian König <christian.koenig@amd.com>

vgaarb: remove vga_conflicts

vga_conflicts only has a single caller and none of the arch overrides
mentioned in the comment. Just remove it and the thus dead check in the
caller.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20210716061634.2446357-3-hch@lst.de
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Christian König <christian.koenig@amd.com>

vgaarb: remove VGA_DEFAULT_DEVICE

The define is entirely unused.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20210716061634.2446357-2-hch@lst.de
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Christian König <christian.koenig@amd.com>

vgaarb: avoid -Wempty-body warnings

Building with W=1 shows a few warnings for an empty macro:

drivers/gpu/drm/qxl/qxl_drv.c: In function 'qxl_pci_probe':
drivers/gpu/drm/qxl/qxl_drv.c:131:50: error: suggest braces around empty body in an 'if' statement [-Werror=empty-body]
131 | vga_put(pdev, VGA_RSRC_LEGACY_IO);
| ^
drivers/gpu/drm/qxl/qxl_drv.c: In function 'qxl_pci_remove':
drivers/gpu/drm/qxl/qxl_drv.c:159:50: error: suggest braces around empty body in an 'if' statement [-Werror=empty-body]
159 | vga_put(pdev, VGA_RSRC_LEGACY_IO);

Change this to an inline function to make it more robust and avoid
the warning.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210322105307.1291840-2-arnd@kernel.org

vgaarb: Remove unneeded semicolons

Remove superfluous semicolons after function definitions.

Signed-off-by: Yue Zou <zouyue3@huawei.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210118010356.214491-1-zouyue3@huawei.com

vgaarb: mark vga_tryget static

This symbols isn't used anywhere outside of vgaarb.c.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20200801061713.307434-1-hch@lst.de

drm: move i915_kick_out_vgacon to vgaarb

Also rename it to vga_remove_vgacon and add kerneldoc text.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20190301092502.30948-2-kraxel@redhat.com

vgaarbiter: rst-ifiy and polish kerneldoc

Move the documentation into Documentation/gpu, link it up and pull in
the kernel doc.

No actual text changes except that I did polish the kerneldoc a bit,
especially for vga_client_register().

v2: Remove some rst from vga-switcheroo.rst that I don't understand,
but which seems to be the reason why the new vgaarbiter.rst sometimes
drops out of the sidebar index.

v3: Drop one level of headings and clarify the vgaarb one a bit.

v4: Fix some typos (Sean).

Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Cc: Sean Paul <seanpaul@chromium.org>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1471034937-651-20-git-send-email-daniel.vetter@ffwll.ch

vgaarb: Stub vga_set_legacy_decoding()

vga_set_legacy_decoding() is defined in drivers/gpu/vga/vgaarb.c,
which is only compiled with CONFIG_VGA_ARB. A caller would
therefore get an undefined symbol if the VGA arbiter is not
enabled.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Acked-by: Dave Airlie <airlied@redhat.com>

vgaarb: Drop obsolete #ifndef

Commit 20cde694027e ("x86, ia64: Move EFI_FB vga_default_device()
initialization to pci_vga_fixup()") moved boot video device detection from
efifb to x86 and ia64 pci/fixup.c.

Remove the left-over #ifndef check that will always match since the
corresponding arch-specific define is gone with above patch.

Signed-off-by: Bruno Prémont <bonbons@linux-vserver.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: Matthew Garrett <matthew.garrett@nebula.com>

Revert "i915: Update VGA arbiter support for newer devices"

This reverts commit 81b5c7bc8de3e6f63419139c2fc91bf81dea8a7d.

Adding drm/i915 into the vga arbiter chain means that X (in a piece of
well-meant paranoia) will do a get/put on the vga decoding around
_every_ accel call down into the ddx. Which results in some nice
performance disasters [1]. This really breaks userspace, by disabling
DRI for everyone, and stops OpenGL from working, this isn't limited
to just the i915 but both the integrated and discrete GPUs on
multi-gpu systems, in other words this causes untold worlds of pain,

Ville tried to come up with a Great Hack to fiddle the required VGA
I/O ops behind everyone's back using stop_machine, but that didn't
really work out [2]. Given that we're fairly late in the -rc stage for
such games let's just revert this all.

One thing we might want to keep is to delay the disabling of the vga
decoding until the fbdev emulation and the fbcon screen is set up. If
we kill vga mem decoding beforehand fbcon can end up with a white
square in the top-left corner it tried to save from the vga memory for
a seamless transition. And we have bug reports on older platforms
which seem to match these symptoms.

But again that's something to play around with in -next.

References: [1] http://lists.x.org/archives/xorg-devel/2013-September/037763.html
References: [2] http://www.spinics.net/lists/intel-gfx/msg34062.html
Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@redhat.com>

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

Fix misspellings of "whether" in comments.

"Whether" is misspelled in various comments across the tree; this
fixes them. No code changes.

Signed-off-by: Adam Buchbinder <adam.buchbinder@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

vgaarb: Provide dummy default device functions

Add some stub functions for the case where CONFIG_VGA_ARB is disabled.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

vgaarb: Provide dummy default device functions

Add some stub functions for the case where CONFIG_VGA_ARB is disabled.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

vgaarb: Add support for setting the default video device (v2)

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: Matthew Garrett <mjg@redhat.com>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Acked-by: benh@kernel.crashing.org
Cc: airlied@redhat.com
Signed-off-by: Dave Airlie <airlied@redhat.com>

vgaarb.h: fix build warnings

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: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>

Fix common misspellings

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>

vgaarb: Wrap vga_(get|put) in CONFIG_VGA_ARB

Fix link failure without the vga arbitrator.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>

vgaarb: drop vga.h include

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

built on powerpc + x86, reported on m68k.

Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>

include/linux/vgaarb.h: add missing part of include guard

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: Doug Goldstein <cardoe@gentoo.org>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>

vgaarb: use MIT license

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

vgaarb: make client interface config invariant.

Fixes build when VGA_ARB is off.

Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Dave Airlie <airlied@redhat.com>

PCI: fix VGA arbiter header file

Remove reference to vgaarb.c and replace it with a comment about the
arbiter itself.

Reported-by: Tiago Vignatti <tiago.vignatti@nokia.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

PCI/vgaarb: cleanup some warnings + cleanup some comments.

Fix some warnings reported in linux-next + also cleanup some
comment errors noticed by Pekka Paalanen.

Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

PCI/GPU: implement VGA arbitration on Linux

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: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Tiago Vignatti <tiago.vignatti@nokia.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>