[Bug 221065] ideapad_acpi: unexpected charge_types spam on Yoga Pro 7 14ASP9

[bugzilla-daemon@kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=221065

--- Comment #34 from Rong Zhang (i@rong.moe) ---
I also found some time looking into ucsi_acpi and the AML code of the ACPI
device (in SSDT17).

Two helper methods (\_SB.PCI0.LPC0.EC0.ECRD for reading,
\_SB.PCI0.LPC0.EC0.ECWT for writing) are repeatedly called a total of 25 (!)
times when handling a UCSI command. Their timeout for acquiring the ECMT mutex
is 1s. Therefore, it is not surprising that some of these calls will time out.

Considering this, it seems that ucsi_acpi will cause significant pressure on
the ECMT mutex, as each UCSI command acquires and releases it 25 times. Instead
of blacklisting ideapad-laptop, could you try to blacklist ucsi_acpi? Doing so
should reduce the pressure on the ECMT mutex a lot, so other ACPI methods may
be less likely to time out. Again, this won't completely "fix" the issue, and a
BIOS update is the only way to fix it.

Moreover, there is no way for us to determine if any call within them has
failed, so we can't trust the UCSI ACPI device anymore -- a quirk will also be
required to disable usci_acpi on 83DR.

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