---
- branch: MAIN
  date: Thu Dec 30 14:40:06 UTC 2021
  files:
  - new: '1.21'
    old: '1.20'
    path: src/sys/dev/acpi/acpi_display.c
    pathrev: src/sys/dev/acpi/acpi_display.c@1.21
    type: modified
  id: 20211230T144006Z.bff5354f382248869995dc001b29b133a72bc223
  log: |
    acpiout(4): Work around firmware that doesn't like some brightnesses.

    Instead of just asking for cur - 5 or cur + 5, repeatedly ask for
    that increment, check whether we actually made progress in that
    direction, and if not keep going with another increment, until we hit
    the bounds of brightness levels.

    I can't find anything in the ACPI spec about this, but my laptop
    seems to have trouble with certain levels: 15, 75, 85, 95.  It goes
    in all other increments of 5 from 5 to 100, just not those ones --
    acts as if the change just never happened, so with the old logic the
    brightness up/down would get stuck unable to move in either
    direction.

    This should have no impact on machines where the first increment
    actually takes.
  module: src
  subject: 'CVS commit: src/sys/dev/acpi'
  unixtime: '1640875206'
  user: riastradh