[Bug 220246] New: Dell Latitude 5400: Mic Mute key stopped to work in v6.15

[Bug 220246] New: Dell Latitude 5400: Mic Mute key stopped to work in v6.15

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https://bugzilla.kernel.org/show_bug.cgi?id=220246

            Bug ID: 220246
           Summary: Dell Latitude 5400: Mic Mute key stopped to work in
                    v6.15
           Product: Drivers
           Version: 2.5
          Hardware: All
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P3
         Component: Platform_x86
          Assignee: drivers_platform_x86@kernel-bugs.osdl.org
          Reporter: dimich.dmb@gmail.com
        Regression: No

Mic Mute key (Fn+F4) stopped to emit input events. 
Before v6.15 pressing Fn+F4 caused `libinput debug-events` to print:

-event8   KEYBOARD_KEY                 +21.508s KEY_MICMUTE (248) pressed
 event8   KEYBOARD_KEY                 +21.508s KEY_MICMUTE (248) released

In v6.15 `libinput debug-events` gives no output when the key is pressed.

Meanwhile, heighbour "media" keys, such as volume up/down, backlight control
etc work fine.

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[Bug 220246] Dell Latitude 5400: Mic Mute key stopped to work in v6.15

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Dmytro Bagrii (dimich.dmb@gmail.com) changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Regression|No                          |Yes

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[Bug 220246] Dell Latitude 5400: Mic Mute key stopped to work in v6.15

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Kurt Borja (kuurtb@gmail.com) changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |kuurtb@gmail.com

--- Comment #1 from Kurt Borja (kuurtb@gmail.com) ---
Hi Dmytro,

(In reply to Dmytro Bagrii from comment #0)
> Mic Mute key (Fn+F4) stopped to emit input events. 
> Before v6.15 pressing Fn+F4 caused `libinput debug-events` to print:
> 
> -event8   KEYBOARD_KEY                 +21.508s KEY_MICMUTE (248) pressed
>  event8   KEYBOARD_KEY                 +21.508s KEY_MICMUTE (248) released

Can you please check which device owns this input event?

It may change from boot to boot so call debug-events again, press the mic mute
key, check the event number and get it's parent's name with

$ libinput list-devices

Additionally, please attach the output of this command before and after the
regression.

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[Bug 220246] Dell Latitude 5400: Mic Mute key stopped to work in v6.15

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--- Comment #2 from Dmytro Bagrii (dimich.dmb@gmail.com) ---
Created attachment 308285
  --> https://bugzilla.kernel.org/attachment.cgi?id=308285&action=edit
Output of `libinput list-devices`

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[Bug 220246] Dell Latitude 5400: Mic Mute key stopped to work in v6.15

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--- Comment #3 from Dmytro Bagrii (dimich.dmb@gmail.com) ---
Hi Kurt,

Please find `libinput list-devices` output attached:
https://bugzilla.kernel.org/attachment.cgi?id=308285

The output is absolutely identical before and after regression.

Source of KEY_MICMUTE before regression is event8, i.e.

Device:                  Dell WMI hotkeys
Kernel:                  /dev/input/event8
Id:                      host:0000:0000
Group:                   8
Seat:                    seat0, default
Capabilities:            keyboard 
Tap-to-click:            n/a
Tap-and-drag:            n/a
Tap button map:          n/a
Tap drag lock:           n/a
Left-handed:             n/a
Nat.scrolling:           n/a
Middle emulation:        n/a
Calibration:             n/a
Scroll methods:          none
Scroll button:           n/a
Scroll button lock:      n/a
Click methods:           none
Clickfinger button map:  n/a
Disable-w-typing:        n/a
Disable-w-trackpointing: n/a
Accel profiles:          n/a
Rotation:                0.0
Area rectangle:          n/a

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[Bug 220246] Dell Latitude 5400: Mic Mute key stopped to work in v6.15

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--- Comment #4 from Kurt Borja (kuurtb@gmail.com) ---
Please, boot into Linux v6.15 and enable dynamic debug for the dell_wmi module:

$ echo 'module dell_wmi +p' | sudo tee /proc/dynamic_debug/control

Follow kernel logs with:

$ dmesg --follow

and then press your mic mute key. After that attach those logs here.

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[Bug 220246] Dell Latitude 5400: Mic Mute key stopped to work in v6.15

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--- Comment #5 from Dmytro Bagrii (dimich.dmb@gmail.com) ---
Created attachment 308287
  --> https://bugzilla.kernel.org/attachment.cgi?id=308287&action=edit
dmesg in 6.15

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[Bug 220246] Dell Latitude 5400: Mic Mute key stopped to work in v6.15

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--- Comment #6 from Dmytro Bagrii (dimich.dmb@gmail.com) ---
Full dmesg output attached:
https://bugzilla.kernel.org/attachment.cgi?id=308287

dmesg output after single Mic Mute key press in 6.15:

dell_wmi: Received WMI event (00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00)

Compare to 6.14.10:

dell_wmi: Received WMI event (02 00 10 00 50 01 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00)
dell_wmi: Process buffer (02 00 10 00 50 01)
dell_wmi: Key with type 0x0010 and code 0x0150 pressed

Also I noted difference in loaded modules. `lsmod | grep dell` In 6.15:

dell_pc                12288  0
platform_profile       16384  1 dell_pc
dell_rbtn              20480  0
dell_laptop            45056  0
dell_smm_hwmon         28672  0
dell_wmi               28672  1 dell_laptop
dell_smbios            36864  3 dell_wmi,dell_pc,dell_laptop
dell_wmi_sysman        61440  0
firmware_attributes_class    12288  1 dell_wmi_sysman
dcdbas                 20480  1 dell_smbios
dell_wmi_descriptor    20480  2 dell_wmi,dell_smbios
dell_lis3lv02d         16384  0
dell_smo8800           16384  0
rfkill                 45056  9 iwlmvm,bluetooth,dell_laptop,dell_rbtn,cfg80211
sparse_keymap          12288  2 intel_hid,dell_wmi
video                  81920  3 dell_wmi,dell_laptop,i915
wmi                    32768  7
dell_wmi_sysman,video,dell_wmi,wmi_bmof,dell_smm_hwmon,dell_smbios,dell_wmi_descriptor

Compare to 6.14.10:

dell_pc                12288  0
platform_profile       16384  1 dell_pc
dell_rbtn              20480  0
dell_laptop            45056  0
dell_smm_hwmon         28672  0
dell_wmi               28672  1 dell_laptop
dell_smbios            36864  3 dell_wmi,dell_pc,dell_laptop
dcdbas                 20480  1 dell_smbios
dell_wmi_sysman        61440  0
dell_lis3lv02d         16384  0
firmware_attributes_class    12288  1 dell_wmi_sysman
dell_wmi_descriptor    20480  2 dell_wmi,dell_smbios
rfkill                 40960  9 iwlmvm,bluetooth,dell_laptop,dell_rbtn,cfg80211
dell_smo8800           16384  0
sparse_keymap          12288  2 intel_hid,dell_wmi
video                  81920  3 dell_wmi,dell_laptop,i915
i8042                  57344  1 dell_laptop
wmi                    32768  7
dell_wmi_sysman,video,dell_wmi,wmi_bmof,dell_smm_hwmon,dell_smbios,dell_wmi_descriptor

Note in "good" case i8042 is loaded and used by dell_laptop module, in "bad"
case it isn't.
I modprobed i8042 in 6.15 just in case. Expectedly, it had no effect.

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[Bug 220246] Dell Latitude 5400: Mic Mute key stopped to work in v6.15

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--- Comment #7 from Dmytro Bagrii (dimich.dmb@gmail.com) ---
UPD: i8042 driver is present in both cases, but in 6.15 it is linked
statically, not as a module. Not sure if this could have an impact.

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[Bug 220246] Dell Latitude 5400: Mic Mute key stopped to work in v6.15

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--- Comment #8 from Dmytro Bagrii (dimich.dmb@gmail.com) ---
Attemt to insert dell_wmi_aio in 6.15 gives:

$ sudo modprobe dell-wmi-aio
modprobe: ERROR: could not insert 'dell_wmi_aio': No such device or address

and in dmesg:

[  601.475130] dell_wmi_aio: No known WMI GUID found

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[Bug 220246] Dell Latitude 5400: Mic Mute key stopped to work in v6.15

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--- Comment #9 from Kurt Borja (kuurtb@gmail.com) ---
On Wed Jun 18, 2025 at 4:42 PM -03, bugzilla-daemon wrote:
> https://bugzilla.kernel.org/show_bug.cgi?id=220246
>
> --- Comment #6 from Dmytro Bagrii (dimich.dmb@gmail.com) ---
> Full dmesg output attached:
> https://bugzilla.kernel.org/attachment.cgi?id=308287
>
> dmesg output after single Mic Mute key press in 6.15:
>
> dell_wmi: Received WMI event (00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00)

Yep, this is the problem. Can you please bisect the WMI core commits
from this cycle? This should do the trick:

$ git bisect start v6.15 v6.14 -- drivers/platform/x86/wmi.c

You are using Arch so you can use

$ make localmodconfig
$ make -j$(nproc) pacman-pkg

to compile.

Maybe (Cc+) Armin Wolf can give us some insight too.

>
> Compare to 6.14.10:
>
> dell_wmi: Received WMI event (02 00 10 00 50 01 00 00 00 00 00 00 00 00 00 00
> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00)
> dell_wmi: Process buffer (02 00 10 00 50 01)
> dell_wmi: Key with type 0x0010 and code 0x0150 pressed

@Armin JFYI:

I have this exact event in my system (Alienware x15 r1) but I can't
reproduce the bug. The WMI event is received just fine.

I also tried upstream v6.15 and v6.16 and this event still works fine.

>
> Also I noted difference in loaded modules. `lsmod | grep dell` In 6.15:
>
> dell_pc                12288  0
> platform_profile       16384  1 dell_pc
> dell_rbtn              20480  0
> dell_laptop            45056  0
> dell_smm_hwmon         28672  0
> dell_wmi               28672  1 dell_laptop
> dell_smbios            36864  3 dell_wmi,dell_pc,dell_laptop
> dell_wmi_sysman        61440  0
> firmware_attributes_class    12288  1 dell_wmi_sysman
> dcdbas                 20480  1 dell_smbios
> dell_wmi_descriptor    20480  2 dell_wmi,dell_smbios
> dell_lis3lv02d         16384  0
> dell_smo8800           16384  0
> rfkill                 45056  9
> iwlmvm,bluetooth,dell_laptop,dell_rbtn,cfg80211
> sparse_keymap          12288  2 intel_hid,dell_wmi
> video                  81920  3 dell_wmi,dell_laptop,i915
> wmi                    32768  7
>
> dell_wmi_sysman,video,dell_wmi,wmi_bmof,dell_smm_hwmon,dell_smbios,dell_wmi_descriptor
>
> Compare to 6.14.10:
>
> dell_pc                12288  0
> platform_profile       16384  1 dell_pc
> dell_rbtn              20480  0
> dell_laptop            45056  0
> dell_smm_hwmon         28672  0
> dell_wmi               28672  1 dell_laptop
> dell_smbios            36864  3 dell_wmi,dell_pc,dell_laptop
> dcdbas                 20480  1 dell_smbios
> dell_wmi_sysman        61440  0
> dell_lis3lv02d         16384  0
> firmware_attributes_class    12288  1 dell_wmi_sysman
> dell_wmi_descriptor    20480  2 dell_wmi,dell_smbios
> rfkill                 40960  9
> iwlmvm,bluetooth,dell_laptop,dell_rbtn,cfg80211
> dell_smo8800           16384  0
> sparse_keymap          12288  2 intel_hid,dell_wmi
> video                  81920  3 dell_wmi,dell_laptop,i915
> i8042                  57344  1 dell_laptop
> wmi                    32768  7
>
> dell_wmi_sysman,video,dell_wmi,wmi_bmof,dell_smm_hwmon,dell_smbios,dell_wmi_descriptor
>
> Note in "good" case i8042 is loaded and used by dell_laptop module, in "bad"
> case it isn't.
> I modprobed i8042 in 6.15 just in case. Expectedly, it had no effect.

Yes, as you already mentioned the i8042 module is unrelated to this bug.

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[Bug 220246] Dell Latitude 5400: Mic Mute key stopped to work in v6.15

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--- Comment #10 from Armin Wolf (W_Armin@gmx.de) ---
Could you please share the output of "acpidump"?

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--- Comment #11 from Dmytro Bagrii (dimich.dmb@gmail.com) ---
Created attachment 308288
  --> https://bugzilla.kernel.org/attachment.cgi?id=308288&action=edit
acpidump

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[Bug 220246] Dell Latitude 5400: Mic Mute key stopped to work in v6.15

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--- Comment #12 from Dmytro Bagrii (dimich.dmb@gmail.com) ---
(In reply to Armin Wolf from comment #10)
> Could you please share the output of "acpidump"?

Attached: https://bugzilla.kernel.org/attachment.cgi?id=308288

Now preparing sources for bisecting.

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--- Comment #13 from Armin Wolf (W_Armin@gmx.de) ---
I think i found the bug myself: it seems that commit 656f0961d126
("platform/x86: wmi: Rework WCxx/WExx ACPI method handling") breaks the WMI
event delivery on your device.

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--- Comment #14 from Armin Wolf (W_Armin@gmx.de) ---
It seems that the WMI event used by the dell-wmi driver is not marked as
expensive, but still requires us to call the enable/disable methods. Since we
only call those methods on devices marked as expensive the WMI event never gets
enabled.

Does the WMI event work under Windows?

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--- Comment #15 from Dmytro Bagrii (dimich.dmb@gmail.com) ---
(In reply to Armin Wolf from comment #14)
> Does the WMI event work under Windows?

Sorry, can't test this. I have no Windows installed.

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[Bug 220246] Dell Latitude 5400: Mic Mute key stopped to work in v6.15

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--- Comment #16 from Armin Wolf (W_Armin@gmx.de) ---
Alright, according the the example code provided my Microsoft it seems that we
are supposed to call the enable methods of WMI events even when they are not
registered as expensive.

I will prepare a patch to fix this, can you test it on your device?

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--- Comment #17 from Dmytro Bagrii (dimich.dmb@gmail.com) ---
(In reply to Armin Wolf from comment #16)
> I will prepare a patch to fix this, can you test it on your device?

Sure. Hopefully tomorrow I will have a chance to do it.

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[Bug 220246] Dell Latitude 5400: Mic Mute key stopped to work in v6.15

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--- Comment #18 from Armin Wolf (W_Armin@gmx.de) ---
Created attachment 308290
  --> https://bugzilla.kernel.org/attachment.cgi?id=308290&action=edit
Prototype patch

This patch should fix the problem. Could you please test it and report back if
the hotkey event works again?

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[Bug 220246] Dell Latitude 5400: Mic Mute key stopped to work in v6.15

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--- Comment #19 from Dmytro Bagrii (dimich.dmb@gmail.com) ---
(In reply to Armin Wolf from comment #18)

> This patch should fix the problem. Could you please test it and report back
> if the hotkey event works again?

Yes, the key works again in 6.15.1 with patch applied.
Thank you!

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--- Comment #20 from Armin Wolf (W_Armin@gmx.de) ---
Nice, i will send the patch upstream then. With a bit of luck it will soon be
picked up by the stable kernels.

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grzegorzssuwaj@gmail.com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |grzegorzssuwaj@gmail.com

--- Comment #21 from grzegorzssuwaj@gmail.com ---
I'd like to confirm that I can also reproduce this on my Dell Precision 3550
with kernel 6.15.3-arch1-1 and your patch also fixed the issue for me. 
Big thanks from me as well!

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--- Comment #22 from Armin Wolf (W_Armin@gmx.de) ---
The patch has been accepted upstream and should appear in the stable kernels in
a short time.

You might now eant to close this bug report.

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Dmytro Bagrii (dimich.dmb@gmail.com) changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |CODE_FIX

--- Comment #23 from Dmytro Bagrii (dimich.dmb@gmail.com) ---
The fix appeared in mainline. Closing the ticket.
Thank you.

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Dmytro Bagrii (dimich.dmb@gmail.com) changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |CLOSED

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