linux-kernel - Re: [PATCH] pwm-backlight: add regulator and GPIO support

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Message-ID: <4FEDD222.7050905@wwwdotorg.org>
Date:	Fri, 29 Jun 2012 10:04:50 -0600
From:	Stephen Warren <swarren@...dotorg.org>
To:	Alexandre Courbot <acourbot@...dia.com>
CC:	Thierry Reding <thierry.reding@...onic-design.de>,
	linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-fbdev@...r.kernel.org
Subject: Re: [PATCH] pwm-backlight: add regulator and GPIO support

On 06/29/2012 07:22 AM, Alexandre Courbot wrote:
> Add support for an optional power regulator and enable/disable GPIO.
> This scheme is commonly used in embedded systems.

> diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c

> -	dev_dbg(&pdev->dev, "got pwm for backlight\n");
> -

That seems like an unrelated change?

> @@ -231,6 +271,22 @@ static int pwm_backlight_probe(struct platform_device *pdev)
>  	if (data->pwm_period_ns > 0)
>  		pwm_set_period(pb->pwm, data->pwm_period_ns);
>  
> +
> +	pb->power_reg = devm_regulator_get(&pdev->dev, "power");

There's an extra blank line there.

> +	if (IS_ERR(pb->power_reg))
> +		return PTR_ERR(pb->power_reg);
> +
> +	pb->enable_gpio = -EINVAL;
> +	if (data->use_enable_gpio) {
> +		ret = devm_gpio_request_one(&pdev->dev, data->enable_gpio,
> +				GPIOF_OUT_INIT_HIGH, "backlight_enable");
> +		if (ret)
> +			dev_warn(&pdev->dev,
> +				"error %d requesting control gpio\n", ret);

Shouldn't that be a hard error? If the user specified that some GPIO be
used, and the GPIO could not be requested, shouldn't the driver fail to
initialize?

> +		else
> +			pb->enable_gpio = data->enable_gpio;

Aside from that, this looks good to me.
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