Comment # 2 on bug 1179905 from Reinhard Max

Thanks, Takashi for the quick response, and yes, it is i915.

# hwinfo --gfxcard
20: PCI 02.0: 0300 VGA compatible controller (VGA)              
  [Created at pci.386]
  Unique ID: _Znp.sD6karQZ3z3
  SysFS ID: /devices/pci0000:00/0000:00:02.0
  SysFS BusID: 0000:00:02.0
  Hardware Class: graphics card
  Device Name: "Onboard IGD"
  Model: "Intel Skylake GT2 [HD Graphics 520]"
  Vendor: pci 0x8086 "Intel Corporation"
  Device: pci 0x1916 "Skylake GT2 [HD Graphics 520]"
  SubVendor: pci 0x1028 "Dell"
  SubDevice: pci 0x06dd 
  Revision: 0x07
  Driver: "i915"
  Driver Modules: "i915"
  Memory Range: 0xe0000000-0xe0ffffff (rw,non-prefetchable)
  Memory Range: 0xd0000000-0xdfffffff (ro,non-prefetchable)
  I/O Ports: 0xf000-0xf03f (rw)
  Memory Range: 0x000c0000-0x000dffff (rw,non-prefetchable,disabled)
  IRQ: 127 (147708 events)
  I/O Ports: 0x3c0-0x3df (rw)
  Module Alias: "pci:v00008086d00001916sv00001028sd000006DDbc03sc00i00"
  Driver Info #0:
    Driver Status: i915 is active
    Driver Activation Cmd: "modprobe i915"
  Config Status: cfg=new, avail=yes, need=no, active=unknown

Primary display adapter: #20

-------------------------------------------------------------------

[    3.892359] fb0: switching to inteldrmfb from VESA VGA
[    3.963879] Console: switching to colour dummy device 80x25
[    3.963913] i915 0000:00:02.0: vgaarb: deactivate vga console
[    3.965694] [drm] Supports vblank timestamp caching Rev 2 (21.10.2013).
[    3.965696] [drm] Driver supports precise vblank timestamp query.
[    3.966430] i915 0000:00:02.0: vgaarb: changed VGA decodes:
olddecodes=io+mem,decodes=io+mem:owns=io+mem
[    3.967850] [drm] Finished loading DMC firmware i915/skl_dmc_ver1_27.bin
(v1.27)
[    3.979238] PM: Image not found (code -22)
[    3.981707] [drm] Initialized i915 1.6.0 20190822 for 0000:00:02.0 on minor
0
[    3.984428] ACPI: Video Device [GFX0] (multi-head: yes  rom: no  post: no)
[    3.985626] input: Video Bus as
/devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/LNXVIDEO:00/input/input3
[    3.993552] fbcon: i915drmfb (fb0) is primary device
[    3.995507] Console: switching to colour frame buffer device 240x67
[    4.015529] i915 0000:00:02.0: fb0: i915drmfb frame buffer device

I will try your suggested options (one after the other?) at my earliest
convenience.