linux-kernel - Re: [RESEND PATCH v5 1/5] pwm-backlight: enable/disable the PWM before/after LCD enable toggle.

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Message-ID: <20180319165829.GB22770@ulmo>
Date:   Mon, 19 Mar 2018 17:58:29 +0100
From:   Thierry Reding <thierry.reding@...il.com>
To:     Enric Balletbo i Serra <enric.balletbo@...labora.com>
Cc:     Lee Jones <lee.jones@...aro.org>,
        Daniel Thompson <daniel.thompson@...aro.org>,
        Jingoo Han <jingoohan1@...il.com>,
        Rob Herring <robh+dt@...nel.org>, Pavel Machek <pavel@....cz>,
        Heiko Stuebner <heiko@...ech.de>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Richard Purdie <rpurdie@...ys.net>,
        Jacek Anaszewski <jacek.anaszewski@...il.com>,
        linux-pwm@...r.kernel.org, linux-fbdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, groeck@...omium.org,
        linux-rockchip@...ts.infradead.org, kernel@...labora.com
Subject: Re: [RESEND PATCH v5 1/5] pwm-backlight: enable/disable the PWM
 before/after LCD enable toggle.

On Fri, Feb 16, 2018 at 06:40:30PM +0100, Enric Balletbo i Serra wrote:
> Before this patch the enable signal was set before the PWM signal and
> vice-versa on power off. This sequence is wrong, at least, it is on
> the different panels datasheets that I checked, so I inverted the sequence
> to follow the specs.
> 
> For reference the following panels have the mentioned sequence:
>   - N133HSE-EA1 (Innolux)
>   - N116BGE (Innolux)
>   - N156BGE-L21 (Innolux)
>   - B101EAN0 (Auo)
>   - B101AW03 (Auo)
>   - LTN101NT05 (Samsung)
>   - CLAA101WA01A (Chunghwa)
> 
> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@...labora.com>
> Acked-by: Daniel Thompson <daniel.thompson@...aro.org>
> Acked-by: Jingoo Han <jingoohan1@...il.com>
> ---
> Changes since v4:
>  - Rebase on top of mainline.
>  - Add the acks from Daniel Thompson and Jingoo Han.
> Changes since v3:
>  - List the part numbers for the panel checked (Daniel Thompson)
> Changes since v2:
>  - Add this as a separate patch (Thierry Reding)
> Changes since v1:
>  - None
> 
>  drivers/video/backlight/pwm_bl.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)

I'm surprised that panels even care about this. Do you see actual
breakage if these are the other way around?

Anyway, this seems to me as legit as the other way around, so:

Acked-by: Thierry Reding <thierry.reding@...il.com>

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