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SubjectRe: [PATCH v3 1/2] dt: bindings: lm3692x: Add bindings for lm3692x LED driver
Pavel and Jacek

On 11/17/2017 10:30 AM, Jingoo Han wrote:
> On Friday, November 17, 2017 6:21 AM, Pavel Machek wrote:
>> Hi!
>>>>> If that does not yet exist... you want to create glue layer to be
>> able
>>>>> to use LED as a display backlight. (It may already exist, no idea).
>>>>> ...
>>>>> Actually or maybe a LED trigger. Just set LED's trigger to "this is
>>>>> display backlight".
>>>> There is one already:
>>>> drivers/leds/trigger/ledtrig-backlight.c
>>>> It adds a LED class device to the fb_notifier_list
>>>> (drivers/video/fbdev/core/fb_notify.c)
>>>> using fb_register_client(). The same is used in
>>>> backlight_device_register (drivers/video/backlight/backlight.c).
>>>> Actually why do you want to have this driver in the LED subsystem,
>>>> if it is advertised as "designed for LCD display backlighting"?
>>> Well this is also advertised as a driver for Smart phone and tablet
>> devices. And having worked with the Android lighting
>>> solutions this is the preferred subsystem for Android. The Android OS
>> manages the led brightness based on ALS values and in
>>> turn calls into the driver to control the brightness register through
>> the vendor provided lighting HAL.
>> Well.. if it can control other LEDs than just backlight, I believe it
>> can stay in the LED subsystem.
> I also agree with your opinion.

I will make the necessary changes for v4.

Just a heads up I won't be posting v4 until after the US holiday so you
don't think I abandoned everything.


> Best regards,
> Jingoo Han
>>> I am going to look at the backlight source to figure out how to get the
>> same functionality using the backlight subsystem.
>>> Otherwise I will plug in this driver to the backlight subsystem through
>> the notifier.
>> The backlight trigger should be ok.
>> Best regards,
> Pavel
>> --
>> (english)
>> (cesky, pictures)

Dan Murphy

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