linux-kernel - Re: [PATCH v6 2/3] mtd: mtk-nor: mtk serial flash controller driver

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Date:	Fri, 13 Nov 2015 15:25:37 +0800
From:	bayi cheng <bayi.cheng@...iatek.com>
To:	Brian Norris <computersforpeace@...il.com>
CC:	David Woodhouse <dwmw2@...radead.org>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	"Ian Campbell" <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Matthias Brugger <matthias.bgg@...il.com>,
	"Daniel Kurtz" <djkurtz@...omium.org>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	<devicetree@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-mediatek@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>, <linux-mtd@...ts.infradead.org>,
	<srv_heupstream@...iatek.com>, <jteki@...nedev.com>,
	<ezequiel@...guardiasur.com.ar>
Subject: Re: [PATCH v6 2/3] mtd: mtk-nor: mtk serial flash controller driver

On Wed, 2015-11-11 at 13:41 -0800, Brian Norris wrote:
> One more small comment, since you're respinning this:
> 
> On Fri, Nov 06, 2015 at 11:48:08PM +0800, Bayi Cheng wrote:
> > diff --git a/drivers/mtd/spi-nor/mtk-quadspi.c b/drivers/mtd/spi-nor/mtk-quadspi.c
> > new file mode 100644
> > index 0000000..6582811
> > --- /dev/null
> > +++ b/drivers/mtd/spi-nor/mtk-quadspi.c
> > @@ -0,0 +1,475 @@
> 
> ...
> 
> > +static int mtk_nor_drv_probe(struct platform_device *pdev)
> > +{
> > +	struct device_node *flash_np;
> > +	struct resource *res;
> > +	int ret;
> > +	struct mt8173_nor *mt8173_nor;
> > +
> > +	if (!pdev->dev.of_node) {
> > +		dev_err(&pdev->dev, "No DT found\n");
> > +		return -EINVAL;
> > +	}
> > +
> > +	mt8173_nor = devm_kzalloc(&pdev->dev, sizeof(*mt8173_nor), GFP_KERNEL);
> > +	if (!mt8173_nor)
> > +		return -ENOMEM;
> > +	platform_set_drvdata(pdev, mt8173_nor);
> > +
> > +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > +	mt8173_nor->base = devm_ioremap_resource(&pdev->dev, res);
> > +	if (IS_ERR(mt8173_nor->base))
> > +		return PTR_ERR(mt8173_nor->base);
> > +
> > +	mt8173_nor->spi_clk = devm_clk_get(&pdev->dev, "spi");
> > +	if (IS_ERR(mt8173_nor->spi_clk)) {
> > +		ret = PTR_ERR(mt8173_nor->spi_clk);
> > +		goto nor_free;
> > +	}
> > +
> > +	mt8173_nor->nor_clk = devm_clk_get(&pdev->dev, "sf");
> > +	if (IS_ERR(mt8173_nor->nor_clk)) {
> > +		ret = PTR_ERR(mt8173_nor->nor_clk);
> > +		goto nor_free;
> > +	}
> > +
> > +	mt8173_nor->dev = &pdev->dev;
> > +	clk_prepare_enable(mt8173_nor->spi_clk);
> > +	clk_prepare_enable(mt8173_nor->nor_clk);
> 
> You enable the clocks here, but...
> 
> > +
> > +	/* only support one attached flash */
> > +	flash_np = of_get_next_available_child(pdev->dev.of_node, NULL);
> > +	if (!flash_np) {
> 
> ... you might bail out here if there is no available flash node, and you
> never disable the clocks. (Same is true if we fail to detect the flash;
> you leave the no-longer-needed clocks enabled.) Seems like maybe you
> should disable clocks on failure.

Yes, I have forgot to disable these clocks on failure. and I will fix it
in the next patch! Thanks!
> 
> > +		dev_err(&pdev->dev, "no SPI flash device to configure\n");
> > +		ret = -ENODEV;
> > +		goto nor_free;
> > +	}
> > +	ret = mtk_nor_init(mt8173_nor, flash_np);
> > +
> > +nor_free:
> > +	return ret;
> > +}
> 
> Brian


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