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

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Date:	Thu, 14 May 2015 22:52:03 +0800
From:	YH Huang <yh.huang@...iatek.com>
To:	Sascha Hauer <s.hauer@...gutronix.de>
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>, <yh.huang@...iatek.com>
Subject: Re: [PATCH 2/2] pwm: add Mediatek display PWM driver support

On Tue, 2015-05-12 at 15:00 +0200, Sascha Hauer wrote:
> 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.
> 

I miss it! Maybe 'mdpc' is a better name for mtk_disp_pwm_chip.

> > +	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.
> 

I forgot this one. I will fix it.

> > +	}
> > +
> > +	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.
> 

OK.

> Sascha
> 

Thank for your suggestion.

Regards,
YH Huang

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