Re: ThinkPad L13 Gen 2 AMD (21AB): Caps Lock LED broken by ACPI GPIO 11 interrupt conflict

[Nikodem Sanecki]

I've tested your patch on my ThinkPad L13 Gen 2 AMD. The Caps Lock LED
works without the kernel parameter, including after cold boots and
suspend/resume. All other hardware I've tested works normally, with no
regressions observed.

Tested-by: Nikodem Sanecki nikodemsanecki@xxxxxxxxx

Thanks for the fix!

On Thu, Oct 15, 2026 at 10:05 PM Nikodem Sanecki
<nikodemsanecki@xxxxxxxxx> wrote:
>
> Hi Mario,
>
> I've created the Bugzilla report and attached the diagnostic evidence:
>
> https://bugzilla.kernel.org/show_bug.cgi?id=222137
>
> I'll test your patch on a separate kernel build without the GPIO11 boot parameter and follow up with the results.
>
> Thanks,
> Nikodem
>
> On Thu, Oct 15, 2026 at 9:26 PM Mario Limonciello <mario.limonciello@xxxxxxx> wrote:
> >
> >
> >
> > On 10/15/26 15:13, Nikodem Sanecki wrote:
> > > Thank you for looking into this.
> > >
> > > I've checked Lenovo's website. My installed BIOS is R1QET54W (1.40),
> > > which matches the latest advertised version. The version history on
> > > their website appears inconsistent, though.
> > >
> >
> > OK thanks.
> >
> > > I also have the sanitised ACPI excerpts and diagnostic logs ready.
> > > Given that a patch has now been submitted, would a kernel Bugzilla
> > > report with these artifacts still be useful?
> >
> > Yes; we should still have the artifacts somewhere.  We can close the bug
> > completed but add a Link: to the patch.
> > >
> > > Happy to help with any further testing.
> >
> > Can you please test the patch I CC'ed you on?
> >
> > https://lore.kernel.org/linux-gpio/20261015193924.4081906-1-mario.limonciello@xxxxxxx/
> >
> > >
> > > Thanks,
> > > Nikodem
> > >
> > > On Thu, Oct 15, 2026 at 8:25 PM Mark Pearson <mpearson-lenovo@xxxxxxxxx> wrote:
> > >>
> > >>
> > >> On Thu, Oct 15, 2026, at 2:48 PM, Mario Limonciello wrote:
> > >>> On 10/15/26 13:31, Andy Shevchenko wrote:
> > >>>> On Thu, Oct 15, 2026 at 09:25:10PM +0300, Andy Shevchenko wrote:
> > >>>>> +Cc: Dmitry (as it might be related to keyboard configuration), others for
> > >>>>> the previously reported same IRQ on the same GPIO controller but for some
> > >>>>> camera stuff.
> > >>>>>
> > >>>>> On Thu, Oct 15, 2026 at 03:13:02PM +0100, Nikodem Sanecki wrote:
> > >>>>>> Hello,
> > >>>>>>
> > >>>>>> I'm reporting a Caps Lock LED issue on my Lenovo ThinkPad L13 Gen 2 AMD
> > >>>>>> running Arch Linux. I found a workaround that completely fixes it, and I
> > >>>>>> hope the findings might help implement a permanent kernel fix.
> > >>>>>>
> > >>>>>> *A quick note:* This is my first time using Linux, and I'm a complete
> > >>>>>> beginner when it comes to kernel development. I used ChatGPT (GPT-6) to
> > >>>>>> guide the troubleshooting process, analyse my laptop's ACPI firmware, and
> > >>>>>> interpret the results. I personally ran the diagnostic commands and
> > >>>>>> verified the observed behaviour, but the technical explanation below is
> > >>>>>> AI-assisted. Please correct me if any of the analysis is inaccurate.
> > >>>>>> Problem
> > >>>>>>
> > >>>>>> Under Linux, the physical Caps Lock indicator LED never illuminates, even
> > >>>>>> though the Caps Lock key itself works normally.
> > >>>>>>
> > >>>>>> The LED works correctly under Windows and during certain stages of boot, so
> > >>>>>> the hardware itself is functional.
> > >>>>>>
> > >>>>>> After investigating, GPT-6 identified what appears to be a conflict
> > >>>>>> involving GPIO 11 on the AMD AMDI0030 controller.
> > >>>>>>
> > >>>>>> Booting Arch Linux with this kernel parameter completely fixes the problem:
> > >>>>>>
> > >>>>>> gpiolib_acpi.ignore_interrupt=AMDI0030:00@11
> > >>>>>>
> > >>>>>> The Caps Lock LED now works normally, and I haven't noticed any other
> > >>>>>> hardware issues.
> > >>>>>> System information
> > >>>>>>
> > >>>>>>      -
> > >>>>>>
> > >>>>>>      Device: Lenovo ThinkPad L13 Gen 2 AMD
> > >>>>>>      -
> > >>>>>>
> > >>>>>>      DMI product name: 21AB004LSP
> > >>>>>>      -
> > >>>>>>
> > >>>>>>      DMI product version/family: ThinkPad L13 Gen 2a
> > >>>>>>      -
> > >>>>>>
> > >>>>>>      DMI vendor: LENOVO
> > >>>>>>      -
> > >>>>>>
> > >>>>>>      DMI product SKU: LENOVO_MT_21AB_BU_Think_FM_ThinkPad L13 Gen 2a
> > >>>>>>      -
> > >>>>>>
> > >>>>>>      Kernel: 7.2.9-arch1-1
> > >>>>>>      -
> > >>>>>>
> > >>>>>>      Distribution: Arch Linux
> > >>>>>>      -
> > >>>>>>
> > >>>>>>      BIOS: R1QET54W (1.40)
> > >>>>>>      -
> > >>>>>>
> > >>>>>>      BIOS date: 2026-04-14
> > >>>>>>      -
> > >>>>>>
> > >>>>>>      DSDT OEM ID: LENOVO
> > >>>>>>      -
> > >>>>>>
> > >>>>>>      DSDT OEM Table ID: TP-R1Q
> > >>>>>>
> > >>>>>> Diagnostic findings
> > >>>>>>
> > >>>>>> The following is GPT-6's analysis of the diagnostic output and decompiled
> > >>>>>> ACPI tables.
> > >>>>>>
> > >>>>>> *1. Linux sends the correct keyboard LED commands*
> > >>>>>>
> > >>>>>> Using bpftrace, we observed that atkbd_set_leds() consistently returned 0.
> > >>>>>>
> > >>>>>> Tracing ps2_command() for command 0x10ED produced:
> > >>>>>>
> > >>>>>> SETLEDS: value=4, caps=1
> > >>>>>> SETLEDS: value=0, caps=0
> > >>>>>> SETLEDS: value=4, caps=1
> > >>>>>> SETLEDS: value=0, caps=0
> > >>>>>>
> > >>>>>> The driver reports success and sends the expected Caps Lock states, but the
> > >>>>>> physical indicator stays off.
> > >>>>>>
> > >>>>>> *2. The embedded controller tracks Caps Lock correctly*
> > >>>>>>
> > >>>>>> The DSDT defines the CPLS field at EC offset 0x0F, bit 7.
> > >>>>>>
> > >>>>>> Reading that byte through the read-only ec_sys interface showed it changing
> > >>>>>> from 0x00 to 0x80 when Caps Lock was toggled.
> > >>>>>>
> > >>>>>> Enabling dynamic debugging in drivers/acpi/ec.c confirmed that each Caps
> > >>>>>> Lock press triggered EC query 0x78, which was scheduled, started and
> > >>>>>> stopped successfully.
> > >>>>>>
> > >>>>>> *3. Lenovo's firmware controls GPIO 11*
> > >>>>>>
> > >>>>>> The DSDT contains:
> > >>>>>>
> > >>>>>> Method (_Q78, 0, NotSerialized)
> > >>>>>> {
> > >>>>>>       If (CPLS)
> > >>>>>>       {
> > >>>>>>           WFIO (0x0B, 0x00)
> > >>>>>>       }
> > >>>>>>       Else
> > >>>>>>       {
> > >>>>>>           WFIO (0x0B, 0x01)
> > >>>>>>       }
> > >>>>>> }
> > >>>>>>
> > >>>>>> The WFIO method writes bit 22 using WMEM(), targeting address 0xFED81500 +
> > >>>>>> (11 * 4) = 0xFED8152C.
> > >>>>>>
> > >>>>>> This appears to control the Caps Lock indicator using GPIO 11.
> > >>>>>>
> > >>>>>> *4. The same GPIO is declared as an ACPI interrupt*
> > >>>>>>
> > >>>>>> In SSDT12, _SB.GPIO._AEI declares GPIO 11 as an edge-triggered, active-low,
> > >>>>>> exclusive wake interrupt.
> > >>>>>>
> > >>>>>> Its _EVT handler includes:
> > >>>>>>
> > >>>>>> Case (0x0B)
> > >>>>>> {
> > >>>>>>       MSTP (0x3911)
> > >>>>>>       Notify (\_SB.PCI0.GPP1, 0x00) // Bus Check
> > >>>>
> > >>>> This looks like some GPIO related notification. I dunno what Windows driver does.
> > >>>> Mario?
> > >>>>
> > >>>
> > >>> Honestly - this sounds like a copy / paste BIOS bug that they copied the
> > >>> SSDT from one system and didn't change it.
> > >>>
> > >>> I would think quirking it makes sense if the BIOS isn't going to be fixed.
> > >>>
> > >>> Before we go much further can you check if this is the latest BIOS?
> > >>> Check Lenovo's website, in case it wasn't brought to LVFS.
> > >>>
> > >>> Also; Mark can you ask BIOS guys to look this over?
> > >>>
> > >>> It sure seems like GPIO 11 shouldn't be in _AEI.
> > >>>
> > >> Yep - created internal ticket LO-4711
> > >> Just a note though - the platform was not in the Linux program (and is rather old) - so my expectations of getting a fix is rather low I'm afraid
> > >>
> > >> I'd get the quirk ready, and if I don't get any feedback from the FW team by next week go ahead with that.
> > >>
> > >> Mark
> >