linux-kernel - Re: [PATCH 0/2] backlight: pwm_bl: prevent backlight flicker when switching PWM on

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Message-ID: <8682e9c4-518d-5dce-55c5-c221dddd5fd6@collabora.com>
Date:   Fri, 10 Nov 2017 12:22:15 +0100
From:   Enric Balletbo i Serra <enric.balletbo@...labora.com>
To:     Daniel Thompson <daniel.thompson@...aro.org>,
        Lothar Waßmann <LW@...O-electronics.de>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Jacek Anaszewski <jacek.anaszewski@...il.com>,
        Jingoo Han <jingoohan1@...il.com>,
        Lee Jones <lee.jones@...aro.org>,
        Mark Rutland <mark.rutland@....com>,
        Pavel Machek <pavel@....cz>,
        Richard Purdie <rpurdie@...ys.net>,
        Rob Herring <robh+dt@...nel.org>,
        Thierry Reding <thierry.reding@...il.com>,
        devicetree@...r.kernel.org, linux-fbdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-leds@...r.kernel.org,
        linux-pwm@...r.kernel.org
Subject: Re: [PATCH 0/2] backlight: pwm_bl: prevent backlight flicker when
 switching PWM on

Hi all,

On 08/11/17 11:48, Daniel Thompson wrote:
> On 26/10/17 13:49, Lothar Waßmann wrote:
>> These patches implement some measures to prevent backlight flicker
>> when the backlight is being switched on for a display with an active
>> low brightness control pin.
>> GIT: [PATCH 1/2] backlight: pwm_bl: Enable PWM before switching regulator
>> GIT: [PATCH 2/2] backlight: pwm_bl: add configurable delay between
> 
> Other than hoisting the pwm_enable() even earlier in the setup sequence this
> patchset seems to have a significant overlap with Enric's recent posting:
> 
>   https://lkml.org/lkml/2017/7/21/211
> 
> Any chance of a shared view on this, especially on the DT bindings?
> 

The DT binding were discussed some time ago for the patch series I sent, though
there isn't a final ack from DT maintainer.

Lothar, the series I sent have been reviewed and acked, can you test if the
series fixes the problem for you too?

Thanks,
 Enric

> 
> 
> Daniel.