reading about the additional flickerfree boot in combination with smooth boot for my laptop got me excited (device is an intel 3rd gen card & i915 driver, kernel 4.19).
for this i created a /etc/modprobe/i915.conf
options i915 fastboot=1
well it did not make much of a difference after a reboot, so i had quick a look at my syslog:
kernel [Firmware Bug]: ACPI(DGFX) defines _DOD but not _DOS
kernel [drm:intel_set_cpu_fifo_underrun_reporting [i915]] ERROR uncleared fifo underrun on pipe A
kernel [drm:intel_cpu_fifo_underrun_irq_handler [i915]] ERROR CPU pipe A FIFO underrun
kernel [drm:intel_set_pch_fifo_underrun_reporting [i915]] ERROR uncleared pch fifo underrun on pch transcoder A
kernel [drm:cpt_irq_handler [i915]] ERROR PCH transcoder A FIFO underrun
kernel radeon 0000:01:00.0: failed VCE resume (-110).
for now i have deleted /etc/modprobe/i915.conf and all is back to normal - except for the vce resume error in syslog, which seems to be an unresolved kernel bug with my (second) radeon card.
is there anything i can do to activate flickerfree boot, too?