Re: ThinkPad T480s & LED_MUTE, LED_MICMUTE

[Pali RohÃr]

On Saturday 16 June 2018 09:05:41 Takashi Iwai wrote:
> On Fri, 15 Jun 2018 21:09:59 +0200,
> Pali RohÃr wrote:
> > 
> > On Friday 15 June 2018 14:51:47 Takashi Iwai wrote:
> > > On Fri, 08 Jun 2018 13:10:57 +0200,
> > > Pali RohÃr wrote:
> > > > 
> > > > Hi! With up-to-date thinkpad_acpi.ko driver on ThinkPad T480s I'm seeing
> > > > a strange behavior of LEDs which are integrated into mic mute (Fn+F4)
> > > > and mute (Fn+F1) keys.
> > > > 
> > > > When thinkpad_acpi.ko is not loaded, then mute key is working fine. When
> > > > pressed, it correctly generates KEY_MUTE on AT Translated Set 2 keyboard
> > > > input device and also turn on/of mute led. But when micmute key is
> > > > pressed then, nothing happen. No key event is reported and also led is
> > > > not turned on/off.
> > > > 
> > > > On the other hand, when thinkpad_acpi.ko is loaded, then both buttons
> > > > mute and micmute correctly generates input events; mute via AT keyboard
> > > > and micmute via ThinkPad Extra Buttons. But led is not changed. When
> > > > thinkpad_acpi.ko is loaded it turn off both leds (mute and micmute) and
> > > > leds after pressing any of those buttons, leds are not turned on again.
> > > > 
> > > > When thinkpad_acpi.ko is unloaded, then pressing mute button again start
> > > > switching led on/off.
> > > > 
> > > > So it seems that some init sequence of thinkpad_acpi.ko breaks mute led.
> > > > And fini sequence of thinkpad_acpi.ko makes mute led working again.
> > > 
> > > Usually the mute LED on Thinkpad is triggered from HD-audio driver
> > > (sound/pci/hda/thinkpad_helper.c), and it's a soft-bound via
> > > symbol_request(tpacpi_led_set).  I thought thinkpad_acpi is
> > > auto-loaded when the module gets bound.
> > > 
> > > A possible explanation would be that TPT480s has neither IBM0068,
> > > LEN0068 nor LEN0268 ACPI HIDs, hence the driver is not auto-loaded.
> > 
> > I have Debian Stretch kernel (4.9) which does not have LEN0268 alias for
> > thinkpad_acpi.ko. So thinkpad_acpi.ko is not loaded automatically. But I
> > have put thinkpad_acpi into /etc/modules and it is now automatically
> > loaded at boot.
> 
> That's odd.  It's exposed via
>   MODULE_DEVICE_TABLE(acpi, ibm_htk_device_ids);
> 
> It's been already in 4.9.  At this point, something is fishy.

$ /sbin/modinfo thinkpad_acpi | grep alias
alias:          dmi:bvnIBM:bvrI[MU]ET??WW*
alias:          tpacpi
alias:          acpi*:LEN0068:*
alias:          acpi*:IBM0068:*

No there is no LEN0268 on 4.9.

> > I also compiled upstream version of thinkpad_acpi.ko, loaded it in
> > Stretch kernel, but it behaves in same way.
> >
> > Maybe... there could be a problem that thinkpad_acpi.ko must be already
> > loaded when sound subsystem is doing initialization? If yes, this could
> > explain it as /etc/modules is loaded at later stage and manually loading
> > of new version of thinkpad_acpi.ko at runtime does not help when sound
> > subsystem is already running.
> 
> Not really.  The HD-audio driver tries to bind with tpacpi_led_set()
> via symbol_request().  i.e. if it's not present, it tries to load a
> module.
> 
> Check whether hda_fixup_thinkpad_acpi() is called and the symbol gets
> loaded or not.
> 
> But, I don't think it's worth to debug such an old kernel primarily.

It is default one used by the last released Debian stable version.

> Could you test the latest Linus tree or 4.17.x at least as a test
> basis?

Ok, will do that later.

> > > (In HD-audio driver side, the ACPI ID is checked and the mute LED
> > >  control is applied only to these three IDs, too.)
> > > Meanwhile, when you load thinkpad_acpi, it does still recognize some
> > > device and initialize it.  By the initialization, it goes out of BIOS
> > > control, and the OS control is expected...   This is my wild guess.
> > > 
> > > 
> > > BTW, the reason we have no LED class for these is that we don't want
> > > to confuse users by providing multiple ways to access to the single
> > > stuff.  We've had already the mute LED control from the audio driver
> > > since long time ago, we don't want to drop and enforce the user-space
> > > solution (that is anyway flakier than in kernel in most cases).
> > 
> > If possible... I would prefer swapped LED behavior: turn led on when
> > microphone is turned on AND turn led off when microphone is turned off.
> > Because current behavior is to have turned led off when microphone is
> > on which seems a bit strange. Also microphone is in majority of time not
> > used and when is not used it is (or should be) turned off. On the other
> > hand e.g. CAPSLOCK led is turned on when CAPSLOCK is enabled (and not
> > opposite) -- which matches uses, it is not used in majority of time.
> 
> Currently the mixer control to change such LED behavior is provided
> only for Dell laptops.  It'd be trivial to port to Thinkpad, though.
> I can provide a patch once after you test with the recent kernels.
> 
> 
> thanks,
> 
> Takashi

-- 
Pali RohÃr
pali.rohar@xxxxxxxxx

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