linux-kernel - RE: [PATCH] platform/x86: dell-laptop: fix phantom kbd backlight on Inspiron 10xx

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Date:   Mon, 23 Sep 2019 13:24:40 +0000
From:   <Mario.Limonciello@...l.com>
To:     <pali.rohar@...il.com>, <pacien.trangirard@...ien.net>
CC:     <mjg59@...f.ucam.org>, <dvhart@...radead.org>,
        <andy@...radead.org>, <platform-driver-x86@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] platform/x86: dell-laptop: fix phantom kbd backlight on
 Inspiron 10xx

> -----Original Message-----
> From: Pali Rohár <pali.rohar@...il.com>
> Sent: Sunday, September 22, 2019 8:43 AM
> To: Pacien TRAN-GIRARD
> Cc: Matthew Garrett; Darren Hart; Andy Shevchenko; platform-driver-
> x86@...r.kernel.org; linux-kernel@...r.kernel.org; Limonciello, Mario
> Subject: Re: [PATCH] platform/x86: dell-laptop: fix phantom kbd backlight on
> Inspiron 10xx
> 
> On Wednesday 18 September 2019 17:29:15 Pacien TRAN-GIRARD wrote:
> > Quoting Pali Rohár (2019-09-12 09:33:58)
> > > On Thursday 12 September 2019 01:14:48 Pacien TRAN-GIRARD wrote:
> > > > This patch registers a quirk disabling keyboard backlight support
> > > > for the Dell Inspiron 1012 and 1018.
> > > >
> > > > Those models wrongly report supporting the KBD_LED_OFF_TOKEN and
> > > > KBD_LED_ON_TOKEN SMBIOS tokens, exposing keyboard brightness
> > > > controls through sysfs which freeze the system when used.
> > > >
> > > > The associated SMBIOS calls never return and cause the system to
> > > > hang, notably at boot when systemd-backlight tries to restore
> > > > previous brightness settings.
> > >
> > > Hi! This sounds like a firmware bug. Have you already reported it to Dell?
> >
> > Yes, the issue has been reported to Dell's technical support, which
> > didn't provide a satisfying answer.
> 
> There were already some firmware problems with keyboard backlight and Mario
> posted this comment about Linux support:
> https://github.com/dell/libsmbios/issues/48#issuecomment-391328501
> 
> Can you try to use libsmbios tools and if they do not work too, report problem
> also there?
> 
> > I'm not familiar with Dell's policy, but I doubt that they would issue
> > a BIOS update for discontinued models from 2010.
> 
> We need to wait what Mario wrote about this particular problem.
> 

I agree an Inspiron is unlikely to be updated 9 years later.  I think the right thing
to do in this instance is to blacklist this particular platform in kernel driver.

> > >
> > > > Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=107651
> > > > Signed-off-by: Pacien TRAN-GIRARD <pacien.trangirard@...ien.net>
> > >
> > > --
> > > Pali Rohr
> > > pali.rohar@...il.com
> >
> > --
> > Pacien TRAN-GIRARD <pacien.trangirard@...ien.net>
> 
> --
> Pali Rohár
> pali.rohar@...il.com