Re: [PATCH] platform/x86: tpacpi: Mark charging LEDs as safe

[Josh Triplett <josh@joshtriplett.org>]

On Sat, Nov 07, 2026 at 07:45:12PM +0800, Rong Zhang wrote:
> Hi Josh,
> 
> On Fri, 2026-11-06 at 15:48 -0800, Josh Triplett wrote:
> > On Sat, Nov 07, 2026 at 04:48:44AM +0800, Rong Zhang wrote:
> > > The term "unsafe LED" exists because LEDs are write-only for software and
> > > fire-and-forget for the EC. By taking the control of an unsafe LED, e.g.,
> > > attaching an LED trigger, any warning signal from the EC can no longer be
> > > displayed by the LED.
> > > 
> > > When it comes to battery LEDs, they are definitely unsafe to override.
> > > After all, batteries are dangerous things when they malfuction. Thus, I
> > > don't think it's suitable to enable it for all users.
> > 
> > Choosing to not report "charging" vs "full" vs "not charging" via LEDs
> > (as opposed to on-screen indicators) is not in itself dangerous. If the
> > EC has something like "battery is damaged/overheating/exploding" to
> > report, it had better do that by some more effective means than blinking
> > an LED, or the message is going to be lost.
> 
> This is not in contradiction to the fact that blinking an LED is crucial.

Something can simultaneously be crucial and completely ineffective. As
mentioned elsewhere in the thread, "immediate shutdown" would be an
improvement. Bonus if a message appears on the screen for a few seconds
so the user has some idea what's going on, but whether the OS handles
that or not, the shutdown would be an improvement.

> > I can't comment on what *every* ThinkPad EC would do, but at least on
> > this X1 Carbon Gen 11, 
>
> That's the whole issue. The patch unlocks charging LEDs on all models,
> while your ThinkPad can't speak on behalf of other models.

If that is the primary concern, would you accept a DMI-identity-based
allowlist?

- Josh