I've been using backlight(8) to set my backlight brightness, and it generally works very well, but I just noticed that if I plug in or unplug my laptop power adapter it will go to 100% brightness. The command output will show 100% brightless, but it appears to remember the previous value, as if I go back to, say, 50% with "backlight 50" it presumably already thinks it's there and will do nothing. If I choose another value, whether higher or lower, it will correctly set that new value, after which backlight(8) will report that value. So: # backlight 50 -> unplug and see backlight brighten # backlight brightness: 100 # backlight 50 -> nothing happens # backlight brightness 100 # backlight 40 -> backlight goes to 40% # backlight brightness: 40 # backlight 50 -> backlight goes to 50% this time # backlight brightness: 50
Sorry, forgot to add some relevant detail. FreeBSD 13, Thinkpad T420, drm-kmod-g20190710_1 and drm-fbsd13-kmod-5.4.92.g20210419 installed, i915kms loaded.
Ok I can reproduce on my laptop too, I'll see how I can fix that.
A commit in branch main references this bug: URL: https://cgit.FreeBSD.org/src/commit/?id=e26ef41f79902991c772b59927c721aa7fa5fc64 commit e26ef41f79902991c772b59927c721aa7fa5fc64 Author: Emmanuel Vadot <manu@FreeBSD.org> AuthorDate: 2022-05-25 14:48:10 +0000 Commit: Emmanuel Vadot <manu@FreeBSD.org> CommitDate: 2022-05-25 14:50:25 +0000 backlight: Update cached value when getting the brightness External events can cause the backlight level to change (AC adapter plug/unplug for example) so cache the value there too. PR: 257796 Sponsored by: Beckhoff Automation GmbH & Co. KG MFC after: 1 week sys/dev/backlight/backlight.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
Sorry for the delay I had totally forgotten about this :( Everything should be fixed now.
A commit in branch stable/13 references this bug: URL: https://cgit.FreeBSD.org/src/commit/?id=b203d3de6b1a7ab38f0a1e3d944a1c4887e31a9b commit b203d3de6b1a7ab38f0a1e3d944a1c4887e31a9b Author: Emmanuel Vadot <manu@FreeBSD.org> AuthorDate: 2022-05-25 14:48:10 +0000 Commit: Emmanuel Vadot <manu@FreeBSD.org> CommitDate: 2022-06-01 07:12:18 +0000 backlight: Update cached value when getting the brightness External events can cause the backlight level to change (AC adapter plug/unplug for example) so cache the value there too. PR: 257796 Sponsored by: Beckhoff Automation GmbH & Co. KG MFC after: 1 week (cherry picked from commit e26ef41f79902991c772b59927c721aa7fa5fc64) sys/dev/backlight/backlight.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)