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From:   Chris Chiu <chiu@endlessm.com>
Date:   Wed, 6 Jun 2018 10:50:05 +0800
Message-ID: <CAB4CAwfZtA8mf4MwJq1AA1wqwJB-HLXuiMmkzkow3NykRsHkSw@mail.gmail.com>
Subject: Re: [PATCH 1/2] platform/x86: asus-wmi: Call new led hw_changed API
 on kbd brightness change
To:     Hans de Goede <hdegoede@redhat.com>
Cc:     Benjamin Berg <benjamin@sipsolutions.net>,
        Bastien Nocera <hadess@hadess.net>,
        Darren Hart <dvhart@infradead.org>,
        Daniel Drake <drake@endlessm.com>,
        Corentin Chary <corentin.chary@gmail.com>,
        Andy Shevchenko <andy.shevchenko@gmail.com>,
        Linux Kernel <linux-kernel@vger.kernel.org>,
        Platform Driver <platform-driver-x86@vger.kernel.org>,
        acpi4asus-user <acpi4asus-user@lists.sourceforge.net>,
        Linux Upstreaming Team <linux@endlessm.com>
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On Tue, Jun 5, 2018 at 7:06 PM, Hans de Goede <hdegoede@redhat.com> wrote:
> Hi,
>
>
> On 05-06-18 12:46, Benjamin Berg wrote:
>>
>> Hey,
>>
>> On Tue, 2018-06-05 at 12:31 +0200, Hans de Goede wrote:
>>>
>>> On 05-06-18 12:14, Bastien Nocera wrote:
>>>>
>>>> On Tue, 2018-06-05 at 12:05 +0200, Hans de Goede wrote:
>>>>>
>>>>> On 05-06-18 11:58, Bastien Nocera wrote:
>>>>>>
>>>>>> [SNIP]
>>>>>
>>>>>
>>>>> Ok, so what are you suggestion, do you really want to hardcode
>>>>> the cycle behavior in the kernel as these 2 patches are doing,
>>>>> without any option to intervene from userspace?
>>>>>
>>>>> As mentioned before in the thread there are several example
>>>>> of the kernel deciding to handle key-presses itself, putting
>>>>> policy in the kernel and they have all ended poorly (think
>>>>> e.g. rfkill, acpi-video dealing with LC brightnesskey presses
>>>>> itself).
>>>>>
>>>>> I guess one thing we could do here is code out both solutions,
>>>>> have a module option which controls if we:
>>>>>
>>>>> 1) Handle this in the kernel as these patches do
>>>>> 2) Or send a new KEY_KBDILLUMCYCLE event
>>>>>
>>>>> Combined with a Kconfig option to select which is the default
>>>>> behavior. Then Endless can select 1 for now and then in
>>>>> Fedora (which defaults to Wayland now) we could default to
>>>>> 2. once all the code for handling 2 is in place.
>>>>>
>>>>> This is ugly (on the kernel side) but it might be the best
>>>>> compromise we can do.
>>>>
>>>>
>>>> I don't really mind which option is used, I'm listing the problems with
>>>> the different options. If you don't care about Xorg, then definitely go
>>>> for adding a new key. Otherwise, processing it in the kernel is the
>>>> least ugly, especially given that the key goes through the same driver
>>>> that controls the brightness anyway. There's no crazy cross driver
>>>> interaction as there was in the other cases you listed.
>>>
>>>
>>> Unfortunately not caring about Xorg is not really an option.
>>>
>>> Ok, new idea, how about we make g-s-d behavior upon detecting a
>>> KEY_KBDILLUMTOGGLE event configurable, if we're on a Mac do a
>>> toggle, otherwise do a cycle.
>>>
>>> Or we could do this through hwdb, then we could add a hwdb entry
>>> for this laptop setting the udev property to do a cycle instead of
>>> a toggle on receiving the keypress.
>>
>>
>> If we are adding hwdb entries anyway to control the userspace
>> interpretation of the TOGGLE key, then we could also add the new CYCLE
>> key and explicitly re-map it to TOGGLE. That requires slightly more
>> logic in hwdb, but it does mean that we could theoretically just drop
>> the workaround if we ever stop caring about Xorg.
>
>
> Hmm, interesting proposal, I say go for it :)
>
> Regards,
>
> Hans
>
>
>

So maybe the next stop is that I can follow Darren's suggestion to eliminate
the is_kbd_led_event() and send a v2 for review?