[SRU] Fix acpi backlight issue on some thinkpads

[AaronMa]

[Impact]
On some ThinkPads, the BIOS reported invalid acpi backlight implement .
Then backlight can't be changed because OS use acpi backlight by default.

[Fix]
Check acpi backlight mode, disable it if invalid.

[Test Case]
Verified on 3 models of thinkpad include Intel/NV/AMD GPU with positive results.

[Regression Potential]
Low
Most ThinkPads now use native backlight control by default.
Check the false acpi mode correctly.

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is missing log files that will aid in diagnosing the problem. While running an Ubuntu kernel (not a mainline or third-party kernel) please enter the following command in a terminal window:

apport-collect 1892010

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the Ubuntu Kernel Team.

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is awaiting verification that the kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-focal' to 'verification-done-focal'. If the problem still exists, change the tag 'verification-needed-focal' to 'verification-failed-focal'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

[AaronMa (mapengyu)]

Tested on 5.6.0-1023-oem, works as expected.

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux-oem-5.6 - 5.6.0-1023.23

---------------
linux-oem-5.6 (5.6.0-1023.23) focal; urgency=medium

  * focal/linux-oem-5.6: 5.6.0-1023.23 -proposed tracker (LP: #1892465)

  * CVE-2020-15852
    - x86/ioperm: Fix io bitmap invalidation on Xen PV

  * Fix non-working USB devices plugged during system sleep (LP: #1892678)
    - xhci: Do warm-reset when both CAS and XDEV_RESUME are set

  * ASPM not enabled on child devices behind VMD controller (LP: #1889384)
    - SAUCE: PCI/ASPM: Enable ASPM for links under VMD domain

  * Fix non-working Goodix touchpad after system sleep (LP: #1891998)
    - HID: i2c-hid: Always sleep 60ms after I2C_HID_PWR_ON commands

  * [SRU] Fix acpi backlight issue on some thinkpads (LP: #1892010)
    - platform/x86: thinkpad_acpi: not loading brightness_init when _BCL invalid

  * Packaging resync (LP: #1786013)
    - [Packaging] update helper scripts

 -- Timo Aaltonen <email address hidden> Tue, 25 Aug 2020 08:46:08 +0300

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux - 5.8.0-18.19

---------------
linux (5.8.0-18.19) groovy; urgency=medium

  * groovy/linux: 5.8.0-18.19 -proposed tracker (LP: #1893047)

  * Packaging resync (LP: #1786013)
    - update dkms package versions

  * Groovy update: v5.8.4 upstream stable release (LP: #1893048)
    - drm/vgem: Replace opencoded version of drm_gem_dumb_map_offset()
    - drm/panel-simple: Fix inverted V/H SYNC for Frida FRD350H54004 panel
    - drm/ast: Remove unused code paths for AST 1180
    - drm/ast: Initialize DRAM type before posting GPU
    - khugepaged: adjust VM_BUG_ON_MM() in __khugepaged_enter()
    - ALSA: hda: avoid reset of sdo_limit
    - ALSA: hda/realtek: Add quirk for Samsung Galaxy Flex Book
    - ALSA: hda/realtek: Add quirk for Samsung Galaxy Book Ion
    - can: j1939: transport: j1939_session_tx_dat(): fix use-after-free read in
      j1939_tp_txtimer()
    - can: j1939: socket: j1939_sk_bind(): make sure ml_priv is allocated
    - spi: Prevent adding devices below an unregistering controller
    - io_uring: find and cancel head link async work on files exit
    - mm/vunmap: add cond_resched() in vunmap_pmd_range
    - romfs: fix uninitialized memory leak in romfs_dev_read()
    - kernel/relay.c: fix memleak on destroy relay channel
    - uprobes: __replace_page() avoid BUG in munlock_vma_page()
    - squashfs: avoid bio_alloc() failure with 1Mbyte blocks
    - mm: include CMA pages in lowmem_reserve at boot
    - mm, page_alloc: fix core hung in free_pcppages_bulk()
    - ASoC: amd: renoir: restore two more registers during resume
    - RDMA/hfi1: Correct an interlock issue for TID RDMA WRITE request
    - opp: Enable resources again if they were disabled earlier
    - opp: Put opp table in dev_pm_opp_set_rate() for empty tables
    - opp: Put opp table in dev_pm_opp_set_rate() if _set_opp_bw() fails
    - ext4: do not block RWF_NOWAIT dio write on unallocated space
    - ext4: fix checking of directory entry validity for inline directories
    - jbd2: add the missing unlock_buffer() in the error path of
      jbd2_write_superblock()
    - scsi: zfcp: Fix use-after-free in request timeout handlers
    - selftests: kvm: Use a shorter encoding to clear RAX
    - s390/pci: fix zpci_bus_link_virtfn()
    - s390/pci: re-introduce zpci_remove_device()
    - s390/pci: fix PF/VF linking on hot plug
    - s390/pci: ignore stale configuration request event
    - mm/memory.c: skip spurious TLB flush for retried page fault
    - drm: amdgpu: Use the correct size when allocating memory
    - drm/amdgpu/display: use GFP_ATOMIC in dcn20_validate_bandwidth_internal
    - drm/amd/display: Fix incorrect backlight register offset for DCN
    - drm/amd/display: Fix EDID parsing after resume from suspend
    - drm/amd/display: Blank stream before destroying HDCP session
    - drm/amd/display: Fix DFPstate hang due to view port changed
    - drm/amd/display: fix pow() crashing when given base 0
    - drm/i915/pmu: Prefer drm_WARN_ON over WARN_ON
    - drm/i915: Provide the perf pmu.module
    - scsi: ufs: Add DELAY_BEFORE_LPM quirk for Micron devices
    - scsi: target: tcmu: Fix crash in tcmu_flush_dcache_range on ARM
  ...

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux - 5.4.0-48.52

---------------
linux (5.4.0-48.52) focal; urgency=medium

  * focal/linux: 5.4.0-48.52 -proposed tracker (LP: #1894654)

  * mm/slub kernel oops on focal kernel 5.4.0-45 (LP: #1895109)
    - SAUCE: Revert "mm/slub: fix a memory leak in sysfs_slab_add()"

  * Packaging resync (LP: #1786013)
    - update dkms package versions
    - update dkms package versions

  * Introduce the new NVIDIA 450-server and the 450 UDA series (LP: #1887674)
    - [packaging] add signed modules for nvidia 450 and 450-server

  * [UBUNTU 20.04] zPCI attach/detach issues with PF/VF linking support
    (LP: #1892849)
    - s390/pci: fix zpci_bus_link_virtfn()
    - s390/pci: re-introduce zpci_remove_device()
    - s390/pci: fix PF/VF linking on hot plug

  * [UBUNTU 20.04] kernel: s390/cpum_cf,perf: changeDFLT_CCERROR counter name
    (LP: #1891454)
    - s390/cpum_cf, perf: change DFLT_CCERROR counter name

  * [UBUNTU 20.04] zPCI: Enabling of a reserved PCI function regression
    introduced by multi-function support (LP: #1891437)
    - s390/pci: fix enabling a reserved PCI function

  * CVE-2020-12888
    - vfio/type1: Support faulting PFNMAP vmas
    - vfio-pci: Fault mmaps to enable vma tracking
    - vfio-pci: Invalidate mmaps and block MMIO access on disabled memory

  * [Hyper-V] VSS and File Copy daemons intermittently fails to start
    (LP: #1891224)
    - [Packaging] Bind hv_vss_daemon startup to hv_vss device
    - [Packaging] bind hv_fcopy_daemon startup to hv_fcopy device

  * alsa/hdmi: support nvidia mst hdmi/dp audio (LP: #1867704)
    - ALSA: hda - Rename snd_hda_pin_sense to snd_hda_jack_pin_sense
    - ALSA: hda - Add DP-MST jack support
    - ALSA: hda - Add DP-MST support for non-acomp codecs
    - ALSA: hda - Add DP-MST support for NVIDIA codecs
    - ALSA: hda: hdmi - fix regression in connect list handling
    - ALSA: hda: hdmi - fix kernel oops caused by invalid PCM idx
    - ALSA: hda: hdmi - preserve non-MST PCM routing for Intel platforms
    - ALSA: hda: hdmi - Keep old slot assignment behavior for Intel platforms
    - ALSA: hda - Fix DP-MST support for NVIDIA codecs

  * Focal update: v5.4.60 upstream stable release (LP: #1892899)
    - smb3: warn on confusing error scenario with sec=krb5
    - genirq/affinity: Make affinity setting if activated opt-in
    - genirq/PM: Always unlock IRQ descriptor in rearm_wake_irq()
    - PCI: hotplug: ACPI: Fix context refcounting in acpiphp_grab_context()
    - PCI: Add device even if driver attach failed
    - PCI: qcom: Define some PARF params needed for ipq8064 SoC
    - PCI: qcom: Add support for tx term offset for rev 2.1.0
    - btrfs: allow use of global block reserve for balance item deletion
    - btrfs: free anon block device right after subvolume deletion
    - btrfs: don't allocate anonymous block device for user invisible roots
    - btrfs: ref-verify: fix memory leak in add_block_entry
    - btrfs: stop incremening log_batch for the log root tree when syncing log
    - btrfs: remove no longer needed use of log_writers for the log root tree
    - btrfs: don't traverse into the seed devices in show_devname
    - btrfs: open device...