My HP laptop has (had) this issue, where the _BQC method (Brightness Query Current level) is missing and our ACPI code throws up its hands and doesn't bother trying to adjust the brightness. I patched my DSDT to add a _BQC method to fix mine, but later I asked the acpica mailing list if a missing _BQC was valid and what we should do about it. They said it was valid and I should maintain the value locally in the OS.
I attached a patch to bug 207086 which maintains the brightness level in a static variable, initially set to 0. If _BQC call fails, from then on the code maintains LCD brightness in the static variable. A possible problem with the code is if there are multiple displays with backlight control, but _BQC doesn't have any concept of multiple displays, so it's a non-problem. Other than that, I probably violated FreeBSD coding standards in several places. I can stick the patch up on Phabricator if desired. References: - Patch - https://bugs.freebsd.org/bugzilla/attachment.cgi?id=187601&action=diff - FreeBSD bug #207086 - https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=207086 - ACPICA mailing list _BQC thread - https://lists.acpica.org/pipermail/devel/2017-January/001074.html _______________________________________________ freebsd-acpi@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-acpi To unsubscribe, send any mail to "freebsd-acpi-unsubscr...@freebsd.org"
