Add DCPD backlight support for HP CML system

[Kai-Heng Feng]

[Impact]
PWM backlight doesn't work on an upcoming HP CML system.

[Fix]
Use DPCD to control backlight instead of PWM.

[Test]
With this patch applied, changing backlight sysfs can change the brightness.

[Regression Potential]
Low. This is specific to panel ID, which is unique.

[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 1871589

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.

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux - 5.4.0-24.28

---------------
linux (5.4.0-24.28) focal; urgency=medium

  * focal/linux: 5.4.0-24.28 -proposed tracker (LP: #1871939)

  * getitimer returns it_value=0 erroneously (LP: #1349028)
    - [Config] CONTEXT_TRACKING_FORCE policy should be unset

  * 12d1:1038 Dual-Role OTG device on non-HNP port - unable to enumerate USB
    device on port 1 (LP: #1047527)
    - [Config] USB_OTG_FSM policy not needed

  * Add DCPD backlight support for HP CML system (LP: #1871589)
    - SAUCE: drm/i915: Force DPCD backlight mode for HP CML 2020 system

  * Backlight brightness cannot be adjusted using keys (LP: #1860303)
    - SAUCE drm/i915: Force DPCD backlight mode for HP Spectre x360 Convertible
      13t-aw100

  * CVE-2020-11494
    - slcan: Don't transmit uninitialized stack data in padding

  * Ubuntu Kernel Support for OpenPOWER NV Secure & Trusted Boot (LP: #1866909)
    - powerpc: Detect the secure boot mode of the system
    - powerpc/ima: Add support to initialize ima policy rules
    - powerpc: Detect the trusted boot state of the system
    - powerpc/ima: Define trusted boot policy
    - ima: Make process_buffer_measurement() generic
    - certs: Add wrapper function to check blacklisted binary hash
    - ima: Check against blacklisted hashes for files with modsig
    - powerpc/ima: Update ima arch policy to check for blacklist
    - powerpc/ima: Indicate kernel modules appended signatures are enforced
    - powerpc/powernv: Add OPAL API interface to access secure variable
    - powerpc: expose secure variables to userspace via sysfs
    - x86/efi: move common keyring handler functions to new file
    - powerpc: Load firmware trusted keys/hashes into kernel keyring
    - x86/efi: remove unused variables

  * [roce-0227]sync mainline kernel 5.6rc3 roce patchset into ubuntu HWE kernel
    branch (LP: #1864950)
    - RDMA/hns: Cleanups of magic numbers
    - RDMA/hns: Optimize eqe buffer allocation flow
    - RDMA/hns: Add the workqueue framework for flush cqe handler
    - RDMA/hns: Delayed flush cqe process with workqueue
    - RDMA/hns: fix spelling mistake: "attatch" -> "attach"
    - RDMA/hns: Initialize all fields of doorbells to zero
    - RDMA/hns: Treat revision HIP08_A as a special case
    - RDMA/hns: Use flush framework for the case in aeq
    - RDMA/hns: Stop doorbell update while qp state error
    - RDMA/hns: Optimize qp destroy flow
    - RDMA/hns: Optimize qp context create and destroy flow
    - RDMA/hns: Optimize qp number assign flow
    - RDMA/hns: Optimize qp buffer allocation flow
    - RDMA/hns: Optimize qp param setup flow
    - RDMA/hns: Optimize kernel qp wrid allocation flow
    - RDMA/hns: Optimize qp doorbell allocation flow
    - RDMA/hns: Check if depth of qp is 0 before configure

  * [hns3-0316]sync mainline kernel 5.6rc4 hns3 patchset into ubuntu HWE kernel
    branch (LP: #1867586)
    - net: hns3: modify an unsuitable print when setting unknown duplex to fibre
    - net: hns3: add enabled TC numbers and DWRR weight info in debugfs
    - net: hns3: add support for dump MAC ID and loopback status in debugfs
    - net: hns3: add missing help info for QS shaper...

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux-oem-5.6 - 5.6.0-1010.10

---------------
linux-oem-5.6 (5.6.0-1010.10) focal; urgency=medium

  * focal/linux-oem-5.6: 5.6.0-1010.10 -proposed tracker (LP: #1876025)

  * built-using constraints preventing uploads (LP: #1875601)
    - temporarily drop Built-Using data

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

  * Focal update: v5.6.8 upstream stable release (LP: #1875938)
    - mm: check that mm is still valid in madvise()
    - tools/testing/nvdimm: Fix compilation failure without
      CONFIG_DEV_DAX_PMEM_COMPAT
    - watchdog: reset last_hw_keepalive time at start
    - scsi: lpfc: Fix kasan slab-out-of-bounds error in lpfc_unreg_login
    - xfs: correctly acount for reclaimable slabs
    - scsi: lpfc: Fix crash after handling a pci error
    - scsi: lpfc: Fix crash in target side cable pulls hitting WAIT_FOR_UNREG
    - scsi: libfc: If PRLI rejected, move rport to PLOGI state
    - ceph: return ceph_mdsc_do_request() errors from __get_parent()
    - ceph: don't skip updating wanted caps when cap is stale
    - pwm: imx27: Fix clock handling in pwm_imx27_apply()
    - pwm: rcar: Fix late Runtime PM enablement
    - nvme-tcp: fix possible crash in write_zeroes processing
    - ASoC: qcom: q6asm-dai: Add SNDRV_PCM_INFO_BATCH flag
    - scsi: iscsi: Report unbind session event when the target has been removed
    - tools/test/nvdimm: Fix out of tree build
    - ASoC: Intel: atom: Take the drv->lock mutex before calling
      sst_send_slot_map()
    - nvme: fix deadlock caused by ANA update wrong locking
    - drm/amd/display: Update stream adjust in dc_stream_adjust_vmin_vmax
    - dma-direct: fix data truncation in dma_direct_get_required_mask()
    - kernel/gcov/fs.c: gcov_seq_next() should increase position index
    - selftests: kmod: fix handling test numbers above 9
    - ipc/util.c: sysvipc_find_ipc() should increase position index
    - kconfig: qconf: Fix a few alignment issues
    - lib/raid6/test: fix build on distros whose /bin/sh is not bash
    - block: fix busy device checking in blk_drop_partitions
    - s390/cio: generate delayed uevent for vfio-ccw subchannels
    - s390/cio: avoid duplicated 'ADD' uevents
    - loop: Better discard support for block devices
    - Revert "powerpc/64: irq_work avoid interrupt when called with hardware irqs
      enabled"
    - powerpc/pseries: Fix MCE handling on pseries
    - nvme: fix compat address handling in several ioctls
    - pwm: renesas-tpu: Fix late Runtime PM enablement
    - pwm: bcm2835: Dynamically allocate base
    - scsi: lpfc: Fix erroneous cpu limit of 128 on I/O statistics
    - scsi: lpfc: Fix lockdep error - register non-static key
    - perf/core: Disable page faults when getting phys address
    - drm/amd/display: Calculate scaling ratios on every medium/full update
    - ASoC: Intel: bytcr_rt5640: Add quirk for MPMAN MPWIN895CL tablet
    - ALSA: usb-audio: Add Pioneer DJ DJM-250MK2 quirk
    - block: fix busy device checking in blk_drop_partitions again
    - cxgb4: fix adapter crash due to wrong MC size
    - cxgb4: fix large delays in PTP synchronization
    - ipv4: Update fib_select_default to ...