Pull arm64 fixes from Catalin Marinas:

 - Fix kernel build with the integrated LLVM assembler which doesn't see
   the -Wa,-march option.

 - Fix "make vdso_install" when COMPAT_VDSO is disabled.

 - Make KVM more robust if the AT S1E1R instruction triggers an
   exception (architecture corner cases).

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  KVM: arm64: Set HCR_EL2.PTW to prevent AT taking synchronous exception
  KVM: arm64: Survive synchronous exceptions caused by AT instructions
  KVM: arm64: Add kvm_extable for vaxorcism code
  arm64: vdso32: make vdso32 install conditional
  arm64: use a common .arch preamble for inline assembly

I keep getting sparse warnings in crypto such as:

  CHECK   drivers/crypto/ccree/cc_hash.c
   drivers/crypto/ccree/cc_hash.c:49:9: warning: cast truncates bits from constant value (47b5481dbefa4fa4 becomes befa4fa4)
   drivers/crypto/ccree/cc_hash.c:49:26: warning: cast truncates bits from constant value (db0c2e0d64f98fa7 becomes 64f98fa7)
   [.. many more ..]

This patch removes the warning by adding a mask to keep sparse
happy.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull writeback fixes from Jan Kara:
 "Fixes for writeback code occasionally skipping writeback of some
  inodes or livelocking sync(2)"

* tag 'writeback_for_v5.9-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
  writeback: Drop I_DIRTY_TIME_EXPIRE
  writeback: Fix sync livelock due to b_dirty_time processing
  writeback: Avoid skipping inode writeback
  writeback: Protect inode->i_io_list with inode->i_lock

Pull gfs2 fix from Andreas Gruenbacher:
 "Fix a memory leak on filesystem withdraw.

  We didn't detect this bug because we have slab merging on by default
  (CONFIG_SLAB_MERGE_DEFAULT). Adding 'slub_nomerge' to the kernel
  command line exposed the problem"

* tag 'gfs2-v5.9-rc2-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2:
  gfs2: add some much needed cleanup for log flushes that fail

Pull ceph fixes from Ilya Dryomov:
 "We have an inode number handling change, prompted by s390x which is a
  64-bit architecture with a 32-bit ino_t, a patch to disallow leases to
  avoid potential data integrity issues when CephFS is re-exported via
  NFS or CIFS and a fix for the bulk of W=1 compilation warnings"

* tag 'ceph-for-5.9-rc3' of git://github.com/ceph/ceph-client:
  ceph: don't allow setlease on cephfs
  ceph: fix inode number handling on arches with 32-bit ino_t
  libceph: add __maybe_unused to DEFINE_CEPH_FEATURE

Pull MFD fixes from Lee Jones:

 - fix double free

 - handle devicetree disabled devices gracefully

* tag 'mfd-fixes-5.9' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/mfd:
  mfd: mfd-core: Ensure disabled devices are ignored without error
  mfd: core: Fix double-free in mfd_remove_devices_fn()

Pull drm fixes from Dave Airlie:
 "As expected a bit of an rc3 uptick, amdgpu and msm are the main ones,
  one msm patch was from the merge window, but had dependencies and we
  dropped it until the other tree had landed. Otherwise it's a couple of
  fixes for core, and etnaviv, and single i915, exynos, omap fixes.

  I'm still tracking the Sandybridge gpu relocations issue, if we don't
  see much movement I might just queue up the reverts. I'll talk to
  Daniel next week once he's back from holidays.

  core:
   - Take modeset bkl for legacy drivers

  dp_mst:
   - Allow null crtc in dp_mst

  i915:
   - Fix command parser desc matching with masks

  amdgpu:
   - Misc display fixes
   - Backlight fixes
   - MPO fix for DCN1
   - Fixes for Sienna Cichlid
   - Fixes for Navy Flounder
   - Vega SW CTF fixes
   - SMU fix for Raven
   - Fix a possible overflow in INFO ioctl
   - Gfx10 clockgating fix

  msm:
   - opp/bw scaling patch followup
   - frequency restoring fux
   - vblank in atomic commit fix
   - dpu modesetting fixes
   - fencing fix

  etnaviv:
   - scheduler interaction fix
   - gpu init regression fix

  exynos:
   - Just drop __iommu annotation to fix sparse warning

  omap:
   - locking state fix"

* tag 'drm-fixes-2020-08-28' of git://anongit.freedesktop.org/drm/drm: (41 commits)
  drm/amd/display: Fix memleak in amdgpu_dm_mode_config_init
  drm/amdgpu: disable runtime pm for navy_flounder
  drm/amd/display: Retry AUX write when fail occurs
  drm/amdgpu: Fix buffer overflow in INFO ioctl
  drm/amd/powerplay: Fix hardmins not being sent to SMU for RV
  drm/amdgpu: use MODE1 reset for navy_flounder by default
  drm/amd/pm: correct the thermal alert temperature limit settings
  drm/amdgpu: add asd fw check before loading asd
  drm/amd/display: Keep current gain when ABM disable immediately
  drm/amd/display: Fix passive dongle mistaken as active dongle in EDID emulation
  drm/amd/display: Revert HDCP disable sequence change
  drm/amd/display: Send DISPLAY_OFF after power down on boot
  drm/amdgpu/gfx10: refine mgcg setting
  drm/amd/pm: correct Vega20 swctf limit setting
  drm/amd/pm: correct Vega12 swctf limit setting
  drm/amd/pm: correct Vega10 swctf limit setting
  drm/amd/pm: set VCN pg per instances
  drm/amd/pm: enable run_btc callback for sienna_cichlid
  drivers: gpu: amd: Initialize amdgpu_dm_backlight_caps object to 0 in amdgpu_dm_update_backlight_caps
  drm/amd/display: Reject overlay plane configurations in multi-display scenarios
  ...

AT instructions do a translation table walk and return the result, or
the fault in PAR_EL1. KVM uses these to find the IPA when the value is
not provided by the CPU in HPFAR_EL1.

If a translation table walk causes an external abort it is taken as an
exception, even if it was due to an AT instruction. (DDI0487F.a's D5.2.11
"Synchronous faults generated by address translation instructions")

While we previously made KVM resilient to exceptions taken due to AT
instructions, the device access causes mismatched attributes, and may
occur speculatively. Prevent this, by forbidding a walk through memory
described as device at stage2. Now such AT instructions will report a
stage2 fault.

Such a fault will cause KVM to restart the guest. If the AT instructions
always walk the page tables, but guest execution uses the translation cached
in the TLB, the guest can't make forward progress until the TLB entry is
evicted. This isn't a problem, as since commit 5dcd0fdb ("KVM: arm64:
Defer guest entry when an asynchronous exception is pending"), KVM will
return to the host to process IRQs allowing the rest of the system to keep
running.

Cc: stable@vger.kernel.org # <v5.3: 5dcd0fdb ("KVM: arm64: Defer guest entry when an asynchronous exception is pending")
Signed-off-by: James Morse <james.morse@arm.com>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

KVM doesn't expect any synchronous exceptions when executing, any such
exception leads to a panic(). AT instructions access the guest page
tables, and can cause a synchronous external abort to be taken.

The arm-arm is unclear on what should happen if the guest has configured
the hardware update of the access-flag, and a memory type in TCR_EL1 that
does not support atomic operations. B2.2.6 "Possible implementation
restrictions on using atomic instructions" from DDI0487F.a lists
synchronous external abort as a possible behaviour of atomic instructions
that target memory that isn't writeback cacheable, but the page table
walker may behave differently.

Make KVM robust to synchronous exceptions caused by AT instructions.
Add a get_user() style helper for AT instructions that returns -EFAULT
if an exception was generated.

While KVM's version of the exception table mixes synchronous and
asynchronous exceptions, only one of these can occur at each location.

Re-enter the guest when the AT instructions take an exception on the
assumption the guest will take the same exception. This isn't guaranteed
to make forward progress, as the AT instructions may always walk the page
tables, but guest execution may use the translation cached in the TLB.

This isn't a problem, as since commit 5dcd0fdb ("KVM: arm64: Defer guest
entry when an asynchronous exception is pending"), KVM will return to the
host to process IRQs allowing the rest of the system to keep running.

Cc: stable@vger.kernel.org # <v5.3: 5dcd0fdb ("KVM: arm64: Defer guest entry when an asynchronous exception is pending")
Signed-off-by: James Morse <james.morse@arm.com>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

KVM has a one instruction window where it will allow an SError exception
to be consumed by the hypervisor without treating it as a hypervisor bug.
This is used to consume asynchronous external abort that were caused by
the guest.

As we are about to add another location that survives unexpected exceptions,
generalise this code to make it behave like the host's extable.

KVM's version has to be mapped to EL2 to be accessible on nVHE systems.

The SError vaxorcism code is a one instruction window, so has two entries
in the extable. Because the KVM code is copied for VHE and nVHE, we end up
with four entries, half of which correspond with code that isn't mapped.
Signed-off-by: James Morse <james.morse@arm.com>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

vdso32 should only be installed if CONFIG_COMPAT_VDSO is enabled,
since it's not even supposed to be compiled otherwise, and arm64
builds without a 32bit crosscompiler will fail.

Fixes: 8d75785a ("ARM64: vdso32: Install vdso32 from vdso_install")
Signed-off-by: Frank van der Linden <fllinden@amazon.com>
Cc: stable@vger.kernel.org [5.4+]
Link: https://lore.kernel.org/r/20200827234012.19757-1-fllinden@amazon.comSigned-off-by: Catalin Marinas <catalin.marinas@arm.com>

Commit 7c78f67e ("arm64: enable tlbi range instructions") breaks
LLVM's integrated assembler, because -Wa,-march is only passed to
external assemblers and therefore, the new instructions are not enabled
when IAS is used.

This change adds a common architecture version preamble, which can be
used in inline assembly blocks that contain instructions that require
a newer architecture version, and uses it to fix __TLBI_0 and __TLBI_1
with ARM64_TLB_RANGE.

Fixes: 7c78f67e ("arm64: enable tlbi range instructions")
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Link: https://github.com/ClangBuiltLinux/linux/issues/1106
Link: https://lore.kernel.org/r/20200827203608.1225689-1-samitolvanen@google.comSigned-off-by: Catalin Marinas <catalin.marinas@arm.com>

Commit e49aa9a9bd22 ("mfd: core: Make a best effort attempt to match
devices with the correct of_nodes") changed the semantics for disabled
devices in mfd_add_device().  Instead of silently ignoring a disabled
child device, an error was returned.  On receipt of the error
mfd_add_devices() the precedes to remove *all* child devices and
returns an all-failed error to the caller, which will inevitably fail
the parent device as well.

This patch reverts back to the old semantics and ignores child devices
which are disabled in Device Tree.

Fixes: e49aa9a9bd22 ("mfd: core: Make a best effort attempt to match devices with the correct of_nodes")
Reported-by: Icenowy Zheng <icenowy@aosc.io>
Tested-by: Icenowy Zheng <icenowy@aosc.io>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

Merge tag 'drm-intel-fixes-2020-08-27' of git://anongit.freedesktop.org/drm/drm-intel into drm-fixes

drm/i915 fixes for v5.9-rc3:
- Fix command parser desc matching with masks
Signed-off-by: Dave Airlie <airlied@redhat.com>
From: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/87imd45ufw.fsf@intel.com

Fixes for v5.9-rc2:
- Take modeset bkl for legacy drivers.
- Allow null crtc in dp_mst.
- Omap locking state fix.
Signed-off-by: Dave Airlie <airlied@redhat.com>

From: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/7af1e52a-27de-8edc-d0b2-e23b01e8bc96@linux.intel.com

Merge tag 'amd-drm-fixes-5.9-2020-08-26' of git://people.freedesktop.org/~agd5f/linux into drm-fixes

amd-drm-fixes-5.9-2020-08-26:

amdgpu:
- Misc display fixes
- Backlight fixes
- MPO fix for DCN1
- Fixes for Sienna Cichlid
- Fixes for Navy Flounder
- Vega SW CTF fixes
- SMU fix for Raven
- Fix a possible overflow in INFO ioctl
- Gfx10 clockgating fix
Signed-off-by: Dave Airlie <airlied@redhat.com>
From: Alex Deucher <alexdeucher@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200826200801.17735-1-alexander.deucher@amd.com

Some fixes for v5.9 plus the one opp/bandwidth scaling patch ("drm:
msm: a6xx: use dev_pm_opp_set_bw to scale DDR") which was not included
in the initial pull due to dependency on patch landing thru OPP tree
Signed-off-by: Dave Airlie <airlied@redhat.com>
From: Rob Clark <robdclark@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/ <CAF6AEGt45A4ObyhEdC5Ga4f4cAf-NBSVRECu7df3Gh6-X4G3tQ@mail.gmail.com

Two fixes:
One fixes a bad interaction with the DRM scheduler, leading to some dma
fences not getting signalled after hitting the job timeout. The other
one fixes a GPU init regression, as apparently one old core doesn't
likes us reading some of the identification registers.
Signed-off-by: Dave Airlie <airlied@redhat.com>
From: Lucas Stach <l.stach@pengutronix.de>
Link: https://patchwork.freedesktop.org/patch/msgid/aceebfe3af636346f5252bdf727cdd988bdcbdf2.camel@pengutronix.de

Merge tag 'exynos-drm-fixes-v5.9-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/daeinki/drm-exynos into drm-fixes

One fixup
- Just drop __iommu annotation to fix sparse warning.
Signed-off-by: Dave Airlie <airlied@redhat.com>

From: Inki Dae <daeinki@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200826071520.3140-1-daeinki@gmail.com

When amdgpu_display_modeset_create_props() fails, state and
state->context should be freed to prevent memleak. It's the
same when amdgpu_dm_audio_init() fails.
Signed-off-by: Dinghao Liu <dinghao.liu@zju.edu.cn>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

Disable runtime pm for navy_flounder temporarily.
Signed-off-by: Jiansong Chen <Jiansong.Chen@amd.com>
Reviewed-by: Tao Zhou <tao.zhou1@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

[Why]
In dm_dp_aux_transfer() now, we forget to handle AUX_WR fail cases. We
suppose every write wil get done successfully and hence some AUX
commands might not sent out indeed.

[How]
Check if AUX_WR success. If not, retry it.
Signed-off-by: Wayne Lin <Wayne.Lin@amd.com>
Reviewed-by: Hersen Wu <hersenxs.wu@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

The values for "se_num" and "sh_num" come from the user in the ioctl.
They can be in the 0-255 range but if they're more than
AMDGPU_GFX_MAX_SE (4) or AMDGPU_GFX_MAX_SH_PER_SE (2) then it results in
an out of bounds read.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

[Why]
DC uses these to raise the voltage as needed for higher dispclk/dppclk
and to ensure that we have enough bandwidth to drive the displays.

There's a bug preventing these from actuially sending messages since
it's checking the actual clock (which is 0) instead of the incoming
clock (which shouldn't be 0) when deciding to send the hardmin.

[How]
Check the clocks != 0 instead of the actual clocks.

Fixes: 9ed9203c ("drm/amd/powerplay: rv dal-pplib interface refactor powerplay part")
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Evan Quan <evan.quan@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

Switch default gpu reset method to MODE1 for navy_flounder.
Signed-off-by: Jiansong Chen <Jiansong.Chen@amd.com>
Reviewed-by: Tao Zhou <tao.zhou1@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

Do the maths in celsius degree. This can fix the issues caused
by the changes below:

drm/amd/pm: correct Vega20 swctf limit setting
drm/amd/pm: correct Vega12 swctf limit setting
drm/amd/pm: correct Vega10 swctf limit setting
Signed-off-by: Evan Quan <evan.quan@amd.com>
Reviewed-by: Kenneth Feng <kenneth.feng@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

asd is not ready for some ASICs in early stage, and psp->asd_fw is more generic than ASIC name in the check.
Signed-off-by: Tao Zhou <tao.zhou1@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Reviewed-by: Jiansong Chen <Jiansong.Chen@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

[Why]
When system enters s3/s0i3, backlight PWM would set user level.

[How]
ABM disable function add keep current gain to avoid it.
Signed-off-by: Brandon Syu <Brandon.Syu@amd.com>
Reviewed-by: Josip Pavic <Josip.Pavic@amd.com>
Acked-by: Eryk Brol <eryk.brol@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

[Why]
dongle_type is set during dongle connection but for passive dongles,
dongle_type is not set. If user starts with an active dongle and
then switches to a passive dongle, it will still report as an active
dongle. Trying to emulate the wrong connecter type results in display
not lighting up.

[How]
Set dpcd_caps.dongle_type for passive dongles in detect_dp().
Signed-off-by: Samson Tam <Samson.Tam@amd.com>
Reviewed-by: Joshua Aberback <Joshua.Aberback@amd.com>
Acked-by: Eryk Brol <eryk.brol@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

[Why]
Revert HDCP disable sequence change that blanks stream before
disabling HDCP. PSP and HW teams are currently investigating the
root cause of why HDCP cannot be disabled before stream blank,
which is expected to work without issues.
Signed-off-by: Jaehyun Chung <jaehyun.chung@amd.com>
Reviewed-by: Wenjing Liu <Wenjing.Liu@amd.com>
Acked-by: Eryk Brol <eryk.brol@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

[WHY]
update_clocks might not be called on headless adapters. This means
DISPLAY_OFF may not be sent in headless cases.

[HOW]
If hardware is powered down on boot because it is headless (mode set
does not happen on that adapter) also send DISPLAY_OFF notification.
Signed-off-by: Sung Lee <sung.lee@amd.com>
Reviewed-by: Yongqiang Sun <yongqiang.sun@amd.com>
Acked-by: Eryk Brol <eryk.brol@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1. enable ENABLE_CGTS_LEGACY to fix specviewperf11 random hang.
2. remove obsolete RLC_CGTT_SCLK_OVERRIDE workaround.
Signed-off-by: Jiansong Chen <Jiansong.Chen@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

Correct the Vega20 thermal swctf limit.
Signed-off-by: Evan Quan <evan.quan@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

Correct the Vega12 thermal swctf limit.
Signed-off-by: Evan Quan <evan.quan@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

Correct the Vega10 thermal swctf limit.

Bug: https://gitlab.freedesktop.org/drm/amd/-/issues/1267Signed-off-by: Evan Quan <evan.quan@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

When deciding whether to set pg for vcn1, instances
number is more generic than chip name.
Signed-off-by: Jiansong Chen <Jiansong.Chen@amd.com>
Reviewed-by: Tao Zhou <tao.zhou1@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

DC BTC support for sienna_cichlid is added, it provides
the DC tolerance and aging measurements.
Signed-off-by: Jiansong Chen <Jiansong.Chen@amd.com>
Reviewed-by: Kenneth Feng <kenneth.feng@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers: gpu: amd: Initialize amdgpu_dm_backlight_caps object to 0 in amdgpu_dm_update_backlight_caps

In `amdgpu_dm_update_backlight_caps()`, there is a local
`amdgpu_dm_backlight_caps` object that is filled in by
`amdgpu_acpi_get_backlight_caps()`. However, this object is
uninitialized before the call and hence the subsequent check for
aux_support can fail since it is not initialized by
`amdgpu_acpi_get_backlight_caps()` as well. This change initializes
this local `amdgpu_dm_backlight_caps` object to 0.
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Furquan Shaikh <furquan@google.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

[Why]
These aren't stable on some platform configurations when driving
multiple displays, especially on higher resolution.

In particular the delay in asserting p-state and validating from
x86 outweights any power or performance benefit from the hardware
composition.

Under some configurations this will manifest itself as extreme stutter
or unresponsiveness especially when combined with cursor movement.

[How]
Disable these for now. Exposing overlays to userspace doesn't guarantee
that they'll be able to use them in any and all configurations and it's
part of the DRM contract to have userspace gracefully handle validation
failures when they occur.

Valdiation occurs as part of DC and this in particular affects RV, so
disable this in dcn10_global_validation.
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Reviewed-by: Hersen Wu <hersenxs.wu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

Documentation for sysfs backlight level interface requires that
values in both 'brightness' and 'actual_brightness' files are
interpreted to be in range from 0 to the value given in the
'max_brightness' file.

With amdgpu, max_brightness gives 255, and values written by the user
into 'brightness' are internally rescaled to a wider range. However,
reading from 'actual_brightness' gives the raw register value without
inverse rescaling. This causes issues for various userspace tools such
as PowerTop and systemd that expect the value to be in the correct
range.

Introduce a helper to retrieve internal backlight range. Use it to
reimplement 'convert_brightness' as 'convert_brightness_from_user' and
introduce 'convert_brightness_to_user'.

Bug: https://bugzilla.kernel.org/show_bug.cgi?id=203905
Bug: https://gitlab.freedesktop.org/drm/amd/-/issues/1242
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alexander Monakov <amonakov@ispras.ru>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org