Date: Sun, 5 Mar 2023 20:19:56 -0600 From: Kyle Evans <kevans@freebsd.org> To: FreeBSD Hackers <freebsd-hackers@freebsd.org> Subject: acpi_cmbat with charge-limited battery Message-ID: <CACNAnaG=vk0jnk4zhvmuW7cRTMFdCuiMJp7mBOMx_rKy7umuoQ@mail.gmail.com>
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Hello! I've dealt with this mainly over the weekend, but my solution was to just disable acpi_cmbat entirely, which is maybe not the best solution but I can't tell if this should be considered a firmware bug or if it's something we could find a way to workaround in the kernel. Basically, I've set the firmware on my frame.work laptop to limit the battery charge to 80%. When it hits 80% while plugged in, things get a little funky- I assume it's because the firmware's trying to carefully maintain the limit, but I end up getting (at least) one acpi notification per second, alternating between BST_CHANGE/BIX_CHANGE, which in turn drives up CPU usage as we tap it out to devd and upowerd picks it up. upowerd ends up pegging a core consistently. Should we be rate-limiting these devd notifications? Is this even reasonable behavior for the firmware? I'm not really sure how other OS behave here, but I haven't really seen any complaints from other framework'ers. Thanks, Kyle Evans
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