linux-kernel - Re: AUXdisplay for LED arrays, keyboards with per-key LEDs -- was Re: [PATCH v2 2/2] leds: add aw20xx driver

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Message-ID: <87h6v4x13q.fsf@intel.com>
Date:   Wed, 01 Mar 2023 11:38:49 +0200
From:   Jani Nikula <jani.nikula@...ux.intel.com>
To:     Pavel Machek <pavel@....cz>,
        Martin Kurbanov <mmkurbanov@...rdevices.ru>, ojeda@...nel.org
Cc:     devicetree@...r.kernel.org, Lee Jones <lee@...nel.org>,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        kernel@...rdevices.ru, linux-leds@...r.kernel.org,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        linux-input@...r.kernel.org
Subject: Re: AUXdisplay for LED arrays, keyboards with per-key LEDs -- was
 Re: [PATCH v2 2/2] leds: add aw20xx driver

On Tue, 28 Feb 2023, Pavel Machek <pavel@....cz> wrote:
> Hi!
>
>> > +config LEDS_AW200XX
>> > +	tristate "LED support for Awinic AW20036/AW20054/AW20072"
>> > +	depends on LEDS_CLASS
>> > +	depends on I2C
>> > +	help
>> > +	  This option enables support for the AW20036/AW20054/AW20072 LED driver.
>> > +	  It is a 3x12/6x9/6x12 matrix LED driver programmed via
>> > +	  an I2C interface, up to 36/54/72 LEDs or 12/18/24 RGBs,
>> > +	  3 pattern controllers for auto breathing or group dimming control.
>> 
>> I'm afraid this should be handled as a display, not as an array of
>> individual LEDs.
>
> You probably want to see
>
> AUXILIARY DISPLAY DRIVERS
> M:      Miguel Ojeda <ojeda@...nel.org>
> S:      Maintained
> F:      Documentation/devicetree/bindings/auxdisplay/
> F:      drivers/auxdisplay/
> F:      include/linux/cfag12864b.h
>
> And this brings another question...
>
> ...sooner or later we'll see LED displays with around 100 pixels in
> almost rectangular grid. Minority of the pixels will have funny
> shapes. How will we handle those? Pretend it is regular display with
> some pixels missing? How do we handle cellphone displays with rounded
> corners and holes for front camera?
>
> And yes, such crazy displays are being manufactured -- it is called
> keyboard with per-key backlight... 
>
> https://www.reddit.com/r/MechanicalKeyboards/comments/8dtvgo/keyboard_with_individually_programmable_leds/

But... is that a display or a HID?

Only half-joking, really. This somewhat reminds me of using input system
force feedback stuff for touch screen vibrations.

Cc: Dmitry & linux-input.


BR,
Jani.

-- 
Jani Nikula, Intel Open Source Graphics Center