Re: [PATCH] Fix AC keyboard backlight timeout on Dell XPS 13 9370.

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On Thursday 31 May 2018 14:35:45 Timur Kristóf wrote:
> On Thu, 2018-05-31 at 14:22 +0200, Pali Rohár wrote:
> > On Thursday 31 May 2018 15:05:39 Andy Shevchenko wrote:
> > > +Cc: Mario
> > > 
> > > On Thu, May 24, 2018 at 9:07 PM, Timur Kristóf <timur.kristof@gmail
> > > .com> wrote:
> > > > From: Timur Kristóf <venemo@xxxxxxxxxxxxxxxxx>
> > > > 
> > > > The 9370 doesn't expose the necessary KBD_LED_AC_TOKEN in the
> > > > BIOS, so the driver thinks it cannot adjust the AC keyboard
> > > > backlight timeout. This patch adds a quirk to fix this until
> > > > Dell adds the missing token to their BIOS.
> > > > 
> > > > For further discussion, see:
> > > > https://github.com/dell/libsmbios/issues/48
> > > > 
> > > 
> > > The change per se looks good to me, though I would hear back from
> > > Pali
> > > and / or Mario on the subject.
> > > Their formal Ack would be enough.
> > 
> > I do not know what is happening here. So Mario should comment if this
> > is
> > really a BIOS bug (and we need to workaround it by DMI whitelisting)
> > or
> > kernel has incorrect implementation (and different fix is needed).
> 
> Discussed with Mario here:
> https://github.com/dell/libsmbios/issues/48
> 
> The conclusion is that this is a BIOS bug. The machine is capable of
> changing the AC keyboard backlight timeout setting, it is just missing
> the token which indicates the capability.

Can you try to report this problem to Dell support (if possible)? Really
if Dell is interested in good Linux support (which looks like yes), then
Dell should know that has a bug in BIOS/firmware which is causing
problems on Linux.

For me it sounds stupid to adding hacks into kernel which just due to
firmware bugs about which vendor does not know.

As a short term fix for one laptop it is OK, but not if Dell starts
producing e.g. new generation of all laptops with same bug. Long term
fix is for sure in BIOS/firmware.

I already wrote this to above github issue.

-- 
Pali Rohár
pali.rohar@xxxxxxxxx



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