linux-kernel - Re: "Setting old previous keyboard state failed" error on Dell E7270

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Date:   Thu, 17 Nov 2016 15:13:59 +0100
From:   Takashi Iwai <tiwai@...e.de>
To:     Pali Rohár <pali.rohar@...il.com>
Cc:     Matthew Garrett <mjg59@...f.ucam.org>,
        platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org,
        gabriele.mzt@...il.com
Subject: Re: "Setting old previous keyboard state failed" error on Dell E7270

On Thu, 17 Nov 2016 14:21:23 +0100,
Takashi Iwai wrote:
> 
> On Thu, 17 Nov 2016 13:19:16 +0100,
> Pali Rohár wrote:
> > 
> > On Thursday 17 November 2016 12:27:33 Takashi Iwai wrote:
> > > Hi,
> > > 
> > > I noticed that a new machine I got yesterday, Dell Latitude E7270,
> > > always shows the error at boot time:
> > > 	dell_laptop: Setting old previous keyboard state failed
> > > 
> > >  From what I read from the code, it seems non-fatal.  But is it a way
> > > to "fix" it?
> > > 
> > > Or shouldn't we simply lower the printk level?
> > > 
> > > 
> > > thanks,
> > > 
> > > Takashi
> > 
> > Hi! Month ago I got private email about same problem reported by user. 
> > Looks like that Dell changed SMBIOS interface for keyboards and have not 
> > notified about it... User wrote that will do some research and write 
> > info to mailing list.
> > 
> > So in this case it is not non-fatal warning, but warning which telling 
> > us: "you are doing some operation which we do not know what is doing 
> > now...".
> > 
> > Masking this warning is not a good idea. There are only two good 
> > options:
> > 
> > 1) Fix the code so it will work with that changed SMBIOS interface
> > 
> > 2) Disable that code on problematic machines.
> > 
> > Anyway, keyboard backlight control in kernel is implemented from program 
> > smbios-keyboard-ctl provided and supported by Dell. I do not see any 
> > update to that program in upstream git repository.
> > 
> > http://github.com/dell/libsmbios/blob/master/src/bin/smbios-keyboard-ctl
> 
> I'll give it a try shortly later.

Tried the latest git version now, and it didn't work.
At setting the mode via smbios-keyboard-ctl --set-mode, it always
return an error like:

  Set Trigger Failed. Failed to write config
	 Error Return Code : cbRES1: 0x-2 cbRES2: 0xA000000 cbRES3: 0x0 

The error code is same no matter which mode is to set.

> > So there are two options what could happen:
> > 
> > 1) smbios-keyboard-ctl is working and kernel code not -- in this case 
> > bug in kernel, please provide debug logs from both smbios-keyboard-ctl 
> > and kernel and I could try to look at it
> > 
> > 2) smbios-keyboard-ctl is not working too -- in this case please report 
> > bug to that libsmbios project and Dell needs to fix it

So the latter case.
I'm going to ping smbios maintainer.


thanks,

Takashi