linux-kernel - Re: [PATCH v2] ACPI: video: Fix missing native backlight on Chromebooks

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Message-ID: <CAJZ5v0irmk3aAK9t3UYcus+SXDL+AaT88LPXfyJU2PrXbkgfMg@mail.gmail.com>
Date:   Mon, 24 Oct 2022 16:45:09 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Hans de Goede <hdegoede@...hat.com>
Cc:     Dmitry Osipenko <dmitry.osipenko@...labora.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Len Brown <lenb@...nel.org>,
        Akihiko Odaki <akihiko.odaki@...nix.com>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Sean Paul <seanpaul@...omium.org>, kernel@...labora.com,
        linux-acpi@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] ACPI: video: Fix missing native backlight on Chromebooks

On Mon, Oct 24, 2022 at 4:32 PM Hans de Goede <hdegoede@...hat.com> wrote:
>
> Hi,
>
> On 10/24/22 16:12, Dmitry Osipenko wrote:
> > Chromebooks don't have backlight in ACPI table, they suppose to use
> > native backlight in this case. Check presence of the CrOS embedded
> > controller ACPI device and prefer the native backlight if EC found.
> >
> > Suggested-by: Hans de Goede <hdegoede@...hat.com>
> > Fixes: 2600bfa3df99 ("ACPI: video: Add acpi_video_backlight_use_native() helper")
> > Signed-off-by: Dmitry Osipenko <dmitry.osipenko@...labora.com>
> > ---
> >
> > Changelog:
> >
> > v2: - Added explanatory comment to the code and added check for the
> >       native backlight presence, like was requested by Hans de Goede.
>
> Thanks this version looks good to me:
>
> Reviewed-by: Hans de Goede <hdegoede@...hat.com>
>
> Rafael, can you pick this up and send it in a fixes pull-req
> for 6.1 to Linus? Or shall I pick this one up and include it
> in my next pull-req?

It would be better if you could pick this up IMV, so please free to add

Acled-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

to it.

Thanks!

> >
> >  drivers/acpi/video_detect.c | 12 ++++++++++++
> >  1 file changed, 12 insertions(+)
> >
> > diff --git a/drivers/acpi/video_detect.c b/drivers/acpi/video_detect.c
> > index 0d9064a9804c..9cd8797d12bb 100644
> > --- a/drivers/acpi/video_detect.c
> > +++ b/drivers/acpi/video_detect.c
> > @@ -668,6 +668,11 @@ static const struct dmi_system_id video_detect_dmi_table[] = {
> >       { },
> >  };
> >
> > +static bool google_cros_ec_present(void)
> > +{
> > +     return acpi_dev_found("GOOG0004");
> > +}
> > +
> >  /*
> >   * Determine which type of backlight interface to use on this system,
> >   * First check cmdline, then dmi quirks, then do autodetect.
> > @@ -730,6 +735,13 @@ static enum acpi_backlight_type __acpi_video_get_backlight_type(bool native)
> >                       return acpi_backlight_video;
> >       }
> >
> > +     /*
> > +      * Chromebooks that don't have backlight handle in ACPI table
> > +      * are supposed to use native backlight if it's available.
> > +      */
> > +     if (google_cros_ec_present() && native_available)
> > +             return acpi_backlight_native;
> > +
> >       /* No ACPI video (old hw), use vendor specific fw methods. */
> >       return acpi_backlight_vendor;
> >  }
>