linux-kernel - Re: [PATCH 1/2] backlight: lp855x: Initialize PWM state on first brightness change

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Message-ID: <20230717083825.GA3448956@aspen.lan>
Date:   Mon, 17 Jul 2023 09:38:25 +0100
From:   Daniel Thompson <daniel.thompson@...aro.org>
To:     Artur Weber <aweber.kernel@...il.com>
Cc:     Lee Jones <lee@...nel.org>, Jingoo Han <jingoohan1@...il.com>,
        Helge Deller <deller@....de>,
        Thierry Reding <thierry.reding@...il.com>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>, dri-devel@...ts.freedesktop.org,
        linux-fbdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-pwm@...r.kernel.org, ~postmarketos/upstreaming@...ts.sr.ht
Subject: Re: [PATCH 1/2] backlight: lp855x: Initialize PWM state on first
 brightness change

On Fri, Jul 14, 2023 at 02:14:39PM +0200, Artur Weber wrote:
> As pointed out by Uwe Kleine-König[1], the changes introduced in
> commit c1ff7da03e16 ("video: backlight: lp855x: Get PWM for PWM mode
> during probe") caused the PWM state set up by the bootloader to be
> re-set when the driver is probed. This differs from the behavior from
> before that patch, where the PWM state would be initialized on the
> first brightness change.
>
> Fix this by moving the PWM state initialization into the PWM control
> function. Add a new variable, needs_pwm_init, to the device info struct
> to allow us to check whether we need the initialization, or whether it
> has already been done.
>
> [1] https://lore.kernel.org/lkml/20230614083953.e4kkweddjz7wztby@pengutronix.de/
>
> Fixes: c1ff7da03e16 ("video: backlight: lp855x: Get PWM for PWM mode during probe")
> Signed-off-by: Artur Weber <aweber.kernel@...il.com>

Reviewed-by: Daniel Thompson <daniel.thompson@...aro.org>