Re: [PATCH 0/2] platform/x86: ideapad-laptop: Fix unexpected charge_types on probe

[Derek J. Clark]

On October 18, 2026 7:19:33 AM PDT, Rong Zhang <i@xxxxxxxx> wrote:
>Hi Derek,
>
>Thanks for you information.
>
>On Sat, 2026-10-17 at 22:30 -0700, Derek J. Clark wrote:
>> On October 17, 2026 4:16:17 PM PDT, Rong Zhang <i@xxxxxxxx> wrote:
>> > It was reported [1] that some unfortunate combinations of BIOS and
>> > Lenovo utilities (e.g., Legion Go 2 + Legion Space) may enable Rapid
>> > Charge and Conservation Mode at the same time, which is very out of
>> > sepc.
>> > 
>> > If both are enabled during a previous Windows boot, ideapad-laptop will
>> > see both bits set and correctly shout "unexpected charge_types".
>> > 
>> > A planned BIOS update will address this. Before that, if unexpected
>> > charge_types are encountered on probe, enforce [Long_Life] to prevent
>> > the device from operating in an out-of-spec state. On check or fix
>> > failure, skip registering the battery hook and the conservation_mode
>> > attribute.
>> > 
>> > Note: the switches never enable themselves autonomously, so there is no
>> > need to fix it during runtime.
>> > 
>> 
>> Hi Rong,
>> 
>> Note that this isn't strictly true. A known bug in multiple Lenovo devices is that querying the EC too quickly can cause it to reset into an invalid state. I.e. some games run under wine for check the state of the AC adapter multiple times a second. In such a case they can reset and then report both modes on. 
>> 
>
>Could you confirm if it's a completely different issue compared to
>https://msgid.link/58586fa666f09c209f9d7fe8c692a8bdda6d4410.camel@xxxxxxxx
>(i.e., an ACPI mutex ABBA deadlock cause the GBMD method to return
>garbage data)?
>

I believe it is. The invalid state survives a power cycle and is preceded by a process hanging for a few seconds before the EC resets. It can be reproduced repeatedly by a simple bash loop that reads the state multiple times a second.

- Derek 
>> I don't believe the device re-enumerates in this case. This is documented in the driver [1].
>
>The comments and the relevant fix was added in a patch of mine. They are
>about yet another different issue, in which querying the EC with an
>interval < 50 *us* causes the EC to shut down the platform.
>
>Then the user must press the power button to power on the platform again.
>It's a cold boot. All kernel drivers are loaded from scratch, so the
>probe-time fix here takes effects.
>
>That being said, as far as I can recall, running into the issue doesn't
>set both modes to enabled. Besides, userspace checking the state of the
>AC adapter multiple times a second must have an interval much larger than
>50 us, so I don't think the issue you described is the same as the issue
>described in the comments either.
>
>> 
>> Lenovo ha mentioned to me a BIOS fix for this issue will be coming for the Go S and Go 2 at some point as well, but this isn't exclusive to Go models. It may be prudent to fix any time an invalid state is detected.
>
>I am OK with the fix-whenever-seen approach, but in this manner it'd be
>better to wait until
>https://msgid.link/20261018122348.679126-1-aliamemis@xxxxxxxxxxx is
>applied to solve the ABBA deadlock issue, so that false positives during
>runtime are reduced.
>
>Thanks,
>Rong
>
>> 
>> Thanks,
>> - Derek
>> 
>> [1] https://github.com/torvalds/linux/blob/32c52ec87d6245ee2d12ed5dd509e40062939b50/drivers/platform/x86/lenovo/ideapad-laptop.c#L286-L296
>> 
>> > Fixes: 90430ea98f55 ("platform/x86: ideapad-laptop: Add charge_types:Fast (Rapid Charge)")
>> > Closes: https://github.com/ValveSoftware/SteamOS/issues/2876 [1]
>> > Signed-off-by: Rong Zhang <i@xxxxxxxx>
>> > ---
>> > Rong Zhang (2):
>> >      platform/x86: ideapad-laptop: Factor out charge_types methods for internal use
>> >      platform/x86: ideapad-laptop: Fix unexpected charge_types on probe
>> > 
>> > drivers/platform/x86/lenovo/ideapad-laptop.c | 113 ++++++++++++++++++++-------
>> > 1 file changed, 84 insertions(+), 29 deletions(-)
>> > ---
>> > base-commit: 58161ead29e50d70a317ea26b472e0c7508e69da
>> > change-id: ef28eda4-ideapad-fix-charge-types-067d46d08945
>> > 
>> > Thanks,
>> > Rong
>> >