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

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Date:   Thu, 17 Nov 2016 14:21:23 +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 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.

> 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

OK.


thanks,

Takashi