Date:   Mon, 18 Jun 2018 12:36:31 +0200
From:   Takashi Iwai <tiwai@...e.de>
To:     Pali Rohár <pali.rohar@...il.com>
Cc:     Henrique de Moraes Holschuh <ibm-acpi@....eng.br>,
        ibm-acpi-devel@...ts.sourceforge.net,
        platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: ThinkPad T480s & LED_MUTE, LED_MICMUTE

On Mon, 18 Jun 2018 12:28:06 +0200,
Pali Rohár wrote:
> 
> On Saturday 16 June 2018 18:02:14 Takashi Iwai wrote:
> > On Sat, 16 Jun 2018 17:43:09 +0200,
> > Pali Rohár wrote:
> > > 
> > > On Saturday 16 June 2018 09:05:41 Takashi Iwai wrote:
> > > > On Fri, 15 Jun 2018 21:09:59 +0200,
> > > > Pali Rohár wrote:
> > > > > 
> > > > > On Friday 15 June 2018 14:51:47 Takashi Iwai wrote:
> > > > > > On Fri, 08 Jun 2018 13:10:57 +0200,
> > > > > > Pali Rohár 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.
> > 
> > OK, that's the cause.  It's really old.
> > 
> > The commit a3c42a467a25 ("platform/x86: thinkpad_acpi: Adding new
> > hotkey ID for Lenovo thinkpad") has to be backported.
> 
> This commit just autoloads thinkpad_acpi driver, right? So manual
> modprobe (for now) is OK too?

Well, the manual modprobe is superfluous if it's properly bound with
HD-audio driver.  The HD-audio driver calls symbol_request(), so it
should do modprobe by itself.

> > Also, in the HD-audio side, the commit 2ecb704a1290 ("ALSA: hda - add
> > a new condition to check if it is thinkpad") is needed, too.
> 
> This commit was introduced in 4.9 and Debian kernel has it. I looked
> into Debian source code and there is check for LEN0268 in file
> sound/pci/hda/thinkpad_helper.c

Then check whether the function gets really called.


> > > > > 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.
> > 
> > Heh, that explains :)
> > 
> > And there was a recent regression in HD-audio that was addressed in
> > 4.9.104.  If you're using some earlier 4.9.x, you might hit the
> > problem regarding HD-audio thinkpad_acpi binding.
> 
> Debian has currently 4.9.88.
> 
> > (But I guess it doesn't work in anyway without the backport of the
> >  commit above.)
> 
> Which change/regression it is? As 2ecb704a1290 is already part of 4.9 I
> think this is a problem why it is not working...

It's 71bff398b0d4 that is in 4.9.104.

But you should really try the latest upstream kernel before spending
too much time (not only yours but also others).


Takashi


> > > > Could you test the latest Linus tree or 4.17.x at least as a test
> > > > basis?
> > > 
> > > Ok, will do that later.
> > 
> > If my analysis above is correct, everything should work with the
> > recent upstream kernel as is.
> > 
> > Once after you confirm it, I can cook a patch to add the mixer enum to
> > change LED behavior as you wanted.
> > 
> > 
> > Takashi
> 
> -- 
> Pali Rohár
> pali.rohar@...il.com
> 

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