linux-kernel - Re: [PATCH v3 4/4] backlight: pwm_bl: Set scale type for brightness curves specified in the DT

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Date:   Mon, 2 Sep 2019 10:42:11 +0100
From:   Lee Jones <lee.jones@...aro.org>
To:     Matthias Kaehlcke <mka@...omium.org>
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Daniel Thompson <daniel.thompson@...aro.org>,
        Jingoo Han <jingoohan1@...il.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        linux-pwm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-fbdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Enric Balletbo i Serra <enric.balletbo@...labora.com>,
        Douglas Anderson <dianders@...omium.org>,
        Brian Norris <briannorris@...omium.org>,
        Pavel Machek <pavel@....cz>,
        Jacek Anaszewski <jacek.anaszewski@...il.com>
Subject: Re: [PATCH v3 4/4] backlight: pwm_bl: Set scale type for brightness
 curves specified in the DT

On Tue, 09 Jul 2019, Matthias Kaehlcke wrote:

> Check if a brightness curve specified in the device tree is linear or
> not and set the corresponding property accordingly. This makes the
> scale type available to userspace via the 'scale' sysfs attribute.
> 
> To determine if a curve is linear it is compared to a interpolated linear
> curve between min and max brightness. The curve is considered linear if
> no value deviates more than +/-5% of ${brightness_range} from their
> interpolated value.
> 
> Signed-off-by: Matthias Kaehlcke <mka@...omium.org>
> Acked-by: Daniel Thompson <daniel.thompson@...aro.org>
> ---
> Changes in v3:
> - none
> 
> Changes in v2:
> - use 128 (power of two) instead of 100 as factor for the slope
> - add comment about max quantization error
> - added Daniel's 'Acked-by' tag
> ---
>  drivers/video/backlight/pwm_bl.c | 30 ++++++++++++++++++++++++++++++
>  1 file changed, 30 insertions(+)

Applied, thanks.

-- 
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
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