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

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Message-ID: <db61f939-a4a2-05ec-e09c-03a95c81e922@redhat.com>
Date:   Mon, 24 Oct 2022 17:12:48 +0200
From:   Hans de Goede <hdegoede@...hat.com>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     Dmitry Osipenko <dmitry.osipenko@...labora.com>,
        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

Hi,

On 10/24/22 16:45, Rafael J. Wysocki wrote:
> 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>

Ok, I've merged this now and I'll send out fixes pull-req with this
to Linus before coming Friday.

Dmitry, Thank you for your patch, I've applied this patch to my
fixes branch:
https://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86.git/log/?h=fixes

Regards,

Hans




> 
> 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;
>>>  }
>>
>