linux-kernel - Re: [PATCH v3 4/5] arm64: dts: sun50i-a64-pinephone: Enable LCD support on PinePhone

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Date:   Fri, 29 May 2020 18:27:28 +0200
From:   Pavel Machek <pavel@....cz>
To:     Ondrej Jirman <megous@...ous.com>
Cc:     linux-sunxi@...glegroups.com,
        Thierry Reding <thierry.reding@...il.com>,
        Sam Ravnborg <sam@...nborg.org>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Rob Herring <robh+dt@...nel.org>,
        Maxime Ripard <mripard@...nel.org>,
        Chen-Yu Tsai <wens@...e.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Icenowy Zheng <icenowy@...c.io>,
        dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        Samuel Holland <samuel@...lland.org>,
        Martijn Braam <martijn@...xit.nl>, Luca Weiss <luca@...tu.xyz>,
        Bhushan Shah <bshah@....org>
Subject: Re: [PATCH v3 4/5] arm64: dts: sun50i-a64-pinephone: Enable LCD
 support on PinePhone

Hi!

> PinePhone uses PWM backlight and a XBD599 LCD panel over DSI for
> display.
> 
> Backlight levels curve was optimized by Martijn Braam using a
> lux meter.

If it was possible to preserve lux values for individual settings in
the comment somewhere... that would be nice :-).

One day, it would be nice to have brightness settings in lux, so I
could easily set matching levels on multiple devices, for example...

Best regards,

								Pavel

> +
> +&backlight {
> +	power-supply = <&reg_ldo_io0>;
> +	/*
> +	 * PWM backlight circuit on this PinePhone revision was changed since
> +	 * 1.0, and the lowest PWM duty cycle that doesn't lead to backlight
> +	 * being off is around 20%. Duty cycle for the lowest brightness level
> +	 * also varries quite a bit between individual boards, so the lowest
> +	 * value here was chosen as a safe default.
> +	 */
> +	brightness-levels = <
> +		774  793  814  842
> +		882  935  1003 1088
> +		1192 1316 1462 1633
> +		1830 2054 2309 2596
> +		2916 3271 3664 4096>;
> +	num-interpolated-steps = <50>;
> +	default-brightness-level = <400>;

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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