From: Pavel Machek <pavel@ucw.cz>
To: Jacek Anaszewski <jacek.anaszewski@gmail.com>
Cc: Jean-Jacques Hiblot <jjhiblot@ti.com>,
devicetree@vger.kernel.org, linux-leds@vger.kernel.org,
robh@kernel.org, "Valkeinen, Tomi" <tomi.valkeinen@ti.com>
Subject: Re: devicetree bindings for a generic led-based backlight driver
Date: Sat, 6 Jul 2019 17:19:41 +0200 [thread overview]
Message-ID: <20190706151941.GB9856@amd> (raw)
In-Reply-To: <e7c5a500-4107-8895-d0fc-377c71cd3b34@gmail.com>
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Hi!
> >>> A few years ago (2015), Tomi Valkeinen posted a series implementing a
> >>> backlight driver on top of a LED device.
> >>>
> >>> https://patchwork.kernel.org/patch/7293991/
> >>> https://patchwork.kernel.org/patch/7294001/
> >>> https://patchwork.kernel.org/patch/7293981/
> >>>
> >>> The discussion stopped because he lacked the time to work on it.
> >>>
> >>> I will be taking over the task and, before heading in the wrong
> >>> direction, wanted a confirmation that the binding Tomi last proposed in
> >>> hist last email was indeed the preferred option.
> >>>
> >>> It will probably require some modifications in the LED core to create
> >>> the right kind of led-device (normal, flash or backlight) based on the
> >>> compatible option.
> >> I recall that discussion. I gave my ack for the LED changes but
> >> now we have more LED people that might want to look into that.
> >
> > Regarding the LED bindings as discussed by Tom and Rob in
> > https://patchwork.kernel.org/patch/7293991/, what do you think of using
> > a 'compatible' string to make a LED device also a backlight or a flash LED ?
>
> After going through the referenced discussion and refreshing my memory
> it looks to me the most reasonable way to go for backlight case.
>
> Nevertheless I'd not tamper at LED flash support - if it's not broken,
> don't fix it.
>
> Best regards,
> Jacek Anaszewski
>
> > Here is the example from Tomi at the end of the discussion:
> >
> > /* tlc59108 is an i2c device */
> > tlc59116@40 {
> > #address-cells = <1>;
> > #size-cells = <0>;
> > compatible = "ti,tlc59108";
> > reg = <0x40>;
> >
> > wan@0 {
> > label = "wrt1900ac:amber:wan";
> > reg = <0x0>;
> > };
> >
> > bl@2 {
> > label = "backlight";
> > reg = <0x2>;
> >
> > compatible = "led-backlight";
> > brightness-levels = <0 243 245 247 248 249 251 252 255>;
> > default-brightness-level = <8>;
> >
> > enable-gpios = <&pcf_lcd 13 GPIO_ACTIVE_LOW>;
So... this needs some kind of reference to display it belongs to,
right?
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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next prev parent reply other threads:[~2019-07-06 15:19 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-26 15:34 devicetree bindings for a generic led-based backlight driver Jean-Jacques Hiblot
2019-06-26 18:55 ` Jacek Anaszewski
2019-06-27 13:14 ` Jean-Jacques Hiblot
2019-06-27 20:19 ` Jacek Anaszewski
2019-07-06 15:19 ` Pavel Machek [this message]
2019-07-10 9:26 ` Jean-Jacques Hiblot
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