linux-kernel - Re: [PATCH 2/2] pwm: add Mediatek display PWM driver support

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Message-ID: <20150512130005.GS6325@pengutronix.de>
Date:	Tue, 12 May 2015 15:00:05 +0200
From:	Sascha Hauer <s.hauer@...gutronix.de>
To:	YH Huang <yh.huang@...iatek.com>
Cc:	Matthias Brugger <matthias.bgg@...il.com>,
	Mark Rutland <mark.rutland@....com>,
	Thierry Reding <thierry.reding@...il.com>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>, linux-pwm@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, srv_heupstream@...iatek.com,
	linux-mediatek@...ts.infradead.org,
	Sascha Hauer <kernel@...gutronix.de>
Subject: Re: [PATCH 2/2] pwm: add Mediatek display PWM driver support

On Mon, May 11, 2015 at 05:26:22PM +0800, YH Huang wrote:
> +
> +static int mtk_disp_pwm_probe(struct platform_device *pdev)
> +{
> +	struct mtk_disp_pwm_chip *pwm;

The struct mtk_disp_pwm_chip * is named 'mpc' in the other functions.
For consistency reasons you should do that here aswell.

> +	struct resource *r;
> +	int ret;
> +
> +	pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
> +	if (!pwm)
> +		return -ENOMEM;
> +
> +	pwm->dev = &pdev->dev;
> +
> +	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	pwm->mmio_base = devm_ioremap_resource(&pdev->dev, r);
> +	if (IS_ERR(pwm->mmio_base))
> +		return PTR_ERR(pwm->mmio_base);
> +
> +	pwm->clk_main = devm_clk_get(&pdev->dev, "main");
> +	if (IS_ERR(pwm->clk_main))
> +		return PTR_ERR(pwm->clk_main);
> +	pwm->clk_mm = devm_clk_get(&pdev->dev, "mm");
> +	if (IS_ERR(pwm->clk_mm))
> +		return PTR_ERR(pwm->clk_mm);
> +
> +	ret = clk_prepare_enable(pwm->clk_main);
> +	if (ret < 0)
> +		return ret;
> +	ret = clk_prepare_enable(pwm->clk_mm);
> +	if (ret < 0) {
> +		clk_disable_unprepare(pwm->clk_main);
> +		return ret;
> +	}
> +
> +	platform_set_drvdata(pdev, pwm);
> +
> +	pwm->chip.dev = &pdev->dev;
> +	pwm->chip.ops = &mtk_disp_pwm_ops;
> +	pwm->chip.base = -1;
> +	pwm->chip.npwm = NUM_PWM;
> +
> +	ret = pwmchip_add(&pwm->chip);
> +	if (ret < 0) {
> +		dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
> +		return ret;

This error path leaves the clocks enabled.

> +	}
> +
> +	return 0;
> +}
> +
> +static int mtk_disp_pwm_remove(struct platform_device *pdev)
> +{
> +	struct mtk_disp_pwm_chip *pc = platform_get_drvdata(pdev);
> +
> +	if (WARN_ON(!pc))
> +		return -ENODEV;
> +
> +	clk_disable_unprepare(pc->clk_main);
> +	clk_disable_unprepare(pc->clk_mm);
> +
> +	return pwmchip_remove(&pc->chip);

You should first remove the pwmchip and disable the clocks afterwards.
Also note that this function can fail.

Sascha

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