Backlight with 4.12: working

Nicolas Huillard nicolas at huillard.net
Sun Jul 9 18:52:01 CEST 2017


Le dimanche 09 juillet 2017 à 14:42 +0200, Wessel Dankers a écrit :
> On 2017‒07‒09 12:10:02+0200, Nicolas Huillard wrote:
> > I finally compiled my own 4.12 kernel, which "works for me".
> > I'll try to separate subjects in order to make the archive more
> > searchable (maybe we can have a definitive status page for the TCM, as
> > it seems that things are settling down cleanly now).
> >
> > Working backlight control :
> > * activate the following kernel config :
> > CONFIG_PWM_LPSS=y
> > CONFIG_PWM_LPSS_PLATFORM=y
> > * actually compile-in those (don't create modules, ie. "=y" instead of
> > "=m"), to be sure that the i915 driver finds the LPSS PWM driver when it
> > initializes, as there is no dependency on those two items
> > * see https://bugs.freedesktop.org/show_bug.cgi?id=96571 for details
> 
> For a different method, see my e-mail dated May 27, repeated here for
> convenience:
> 
> ---
> 
> One more thing: to get working brightness controls I had to add
> pwm_lpss_platform to /etc/initramfs-tools/modules to force a module loading
> order (otherwise I'd get “failed to own the pwm chip” from the i915 drm
> driver).
> 
> 	https://bugs.freedesktop.org/show_bug.cgi?id=96571
> 
> ---

I started from this very email, and noticed that I didn't have this
module in my kernel. I thus read the bug thread, and instead of creating
a module and bothering with adding it to the initramfs, I just compiled
it in the kernel, because we will need to continue to compile kernels at
least until someone finds a solution re. the ELAN0800 keyboard/trackpad
support.

Thanks for your work, which is very valuable, along with the work from
Paul and others.

-- 
Nicolas Huillard



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