Re: Brightness 100% when connect or disconnect charger

It's working!
I just added

      return 0;

below if_def_linux so it will always return 0 and when I plug and
unplug my charger it never goes to 100

Thank You
Dr. Amr Osman


Thank You
Dr. Amr Osman




On Fri, Nov 10, 2023 at 1:10 PM Emmanuel Vadot <manu@bidouilliste.com> wrote:
>
> On Thu, 9 Nov 2023 09:19:31 +0100
> Emmanuel Vadot <manu@bidouilliste.com> wrote:
>
> > On Wed, 8 Nov 2023 21:57:21 +0200
> > "Dr. Amr Osman" <dr3mro@gmail.com> wrote:
> >
> > > Hello,
> > > I have installed freeBSD 14rc4 on Lenovo Thinkpad x270 and xfce desktop and
> > > when I
> > > 1) connect the charger
> > > 2) disconnect the charger
> > > 3) resume from suspend
> > > The LCD brightness is 100% which is really disturbing specially when I am
> > > in dark room
> >
> >  I don't have the issue on my Thinkpad X390 with suspend/resume but I
> > do have it with the charger.
> >  I'm pretty sure that it's a hardware thing and we can't do anything
> > about it without having some framework for sensors that can handle
> > power supply connection/disconnection and events.
> >
> > > hw.acpi.video.lcd0.economy: 20
> > > hw.acpi.video.lcd0.fullpower: 30
> > > I have loaded acpi_video and acpi_ibm
> > > and if I tried to adjust brightness it goes suddenly from 100 to 20 if I
> > > press fn +f5/f6
> >
> >  You shouldn't need to load acpi_video on modern laptop, backlight(9)
> > and backlight(8) is enought (if you have drm loaded).
> >
> > > What can I do to fix this issue?
>
>  So I had a better look at I was only ~50% right :)
>  There is some harware thing that happens, when some external events
> happens (docking, plugging charger, suspend/resume etc ...) the
> gpu firmware (or the IP not sure about which) generates some interrupts
> and the i915 driver get some messages via some mailbox. We seem to get
> a set backlight message for those events, it's happening
> https://github.com/freebsd/drm-kmod/blob/dce1b3ba0d1ff8ccbbbec09d74480a3a0de346e4/drivers/gpu/drm/i915/display/intel_opregion.c#L420
>  There is a few things that I still don't understand :
>  - Why do we get a message to set the backlight at 100% for any of
> those events ?
> - Linux checks the backlight type and if it's "native" they discard
> this call. Still unsure what "native" really means, looking at some
> code it seems that if acpi_video is used it's not considered as a
> native backlight unless there is a quirk for the computer or if in the
> ACPI table it's says that it's a windows 8 laptop or some chromebook.
> - Modifying the above function to always returns 0 (so faking that we
> have a "native" backlight) obviously don't change the backlight value,
> but I'm unsure if this is the correct hack or if there will be some
> problems with it.
>
>  So it will be interesting for people who have this problem to know if
> modifying the code to always do a return 0; at the beginning fixes
> everything. I'd also like to know if the keyboard keys to modify the
> backlight still works correctly after this (mine don't do a thing and
> never did, one day I should have a look at how to use them).
>
>  Cheers,
>
> --
> Emmanuel Vadot <manu@bidouilliste.com> <manu@freebsd.org>