linux-kernel - Re: [PATCH 2/2] backlight: pwm_bl: Check the pwm state for initial backlight power state

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Message-ID: <20161026121329.GR8574@dell>
Date:   Wed, 26 Oct 2016 13:13:29 +0100
From:   Lee Jones <lee.jones@...aro.org>
To:     Peter Ujfalusi <peter.ujfalusi@...com>
Cc:     thierry.reding@...il.com, jingoohan1@...il.com,
        tomi.valkeinen@...com, linux-pwm@...r.kernel.org,
        linux-fbdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        p.zabel@...gutronix.de
Subject: Re: [PATCH 2/2] backlight: pwm_bl: Check the pwm state for initial
 backlight power state

On Fri, 30 Sep 2016, Peter Ujfalusi wrote:

> If the pwm is not enabled the backlight initially should not be enabled
> either if we have booted with DT and there is a phandle pointing to the
> backlight node.
> 
> The patch extends the checks to decide if we should keep the backlight off
> initially.
> 
> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@...com>
> ---
>  drivers/video/backlight/pwm_bl.c | 4 ++++
>  1 file changed, 4 insertions(+)

Makes sense to me.

I'm going to apply this until someone screams at me.

> diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
> index 9bc4715bf116..e4326bbf807f 100644
> --- a/drivers/video/backlight/pwm_bl.c
> +++ b/drivers/video/backlight/pwm_bl.c
> @@ -223,6 +223,10 @@ static int pwm_backlight_initial_power_state(const struct pwm_bl_data *pb)
>  	if (!regulator_is_enabled(pb->power_supply))
>  		return FB_BLANK_POWERDOWN;
>  
> +	/* The pwm is disabled, keep it like this */
> +	if (!pwm_is_enabled(pb->pwm))
> +		return FB_BLANK_POWERDOWN;
> +
>  	return FB_BLANK_UNBLANK;
>  }
>  

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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