linux-kernel - Re: [PATCH v8 2/4] pinctrl: cygnus: add gpio/pinconf driver

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Message-ID: <54DA7C79.2010606@broadcom.com>
Date:	Tue, 10 Feb 2015 13:47:37 -0800
From:	Ray Jui <rjui@...adcom.com>
To:	Dmitry Torokhov <dtor@...omium.org>
CC:	Linus Walleij <linus.walleij@...aro.org>,
	Alexandre Courbot <gnurou@...il.com>,
	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>,
	"Grant Likely" <grant.likely@...aro.org>,
	Christian Daudt <bcm@...thebug.org>,
	Matt Porter <mporter@...aro.org>,
	Florian Fainelli <f.fainelli@...il.com>,
	Russell King <linux@....linux.org.uk>,
	Joe Perches <joe@...ches.com>, "Arnd Bergmann" <arnd@...db.de>,
	Scott Branden <sbranden@...adcom.com>,
	"Anatol Pomazau" <anatol@...gle.com>,
	<linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-gpio@...r.kernel.org>,
	<bcm-kernel-feedback-list@...adcom.com>,
	<devicetree@...r.kernel.org>
Subject: Re: [PATCH v8 2/4] pinctrl: cygnus: add gpio/pinconf driver



On 2/9/2015 11:20 AM, Dmitry Torokhov wrote:
> Hi Ray,
> 
> On Wed, Feb 04, 2015 at 09:21:01AM -0800, Ray Jui wrote:
>> +static int cygnus_gpio_pinmux_add_range(struct cygnus_gpio *chip)
>> +{
>> +	struct device_node *node = chip->dev->of_node;
>> +	struct device_node *pinmux_node;
>> +	struct platform_device *pinmux_pdev;
>> +	struct gpio_chip *gc = &chip->gc;
>> +	int i, ret;
>> +
>> +	/* parse DT to find the phandle to the pinmux controller */
>> +	pinmux_node = of_parse_phandle(node, "pinmux", 0);
>> +	if (!pinmux_node)
>> +		return -ENODEV;
>> +
>> +	pinmux_pdev = of_find_device_by_node(pinmux_node);
>> +	if (!pinmux_pdev) {
>> +		dev_err(chip->dev, "failed to get pinmux device\n");
>> +		return -EINVAL;
>> +	}
>> +
>> +	/* now need to create the mapping between local GPIO and PINMUX pins */
>> +	for (i = 0; i < ARRAY_SIZE(cygnus_gpio_pintable); i++) {
>> +		ret = gpiochip_add_pin_range(gc, dev_name(&pinmux_pdev->dev),
>> +					     cygnus_gpio_pintable[i].offset,
>> +					     cygnus_gpio_pintable[i].pin_base,
>> +					     cygnus_gpio_pintable[i].num_pins);
>> +		if (ret) {
>> +			dev_err(chip->dev, "unable to add GPIO pin range\n");
>> +			goto err_put_device;
>> +		}
>> +	}
>> +
>> +	chip->pinmux_is_supported = true;
>> +
>> +	/* no need for pinmux_pdev device reference anymore */
>> +	put_device(&pinmux_pdev->dev);
> 
> Sorry I did not notice it before, but of_parse_phandle() takes reference
> to the returned device node, so you need to "put" it here and in error
> path as well. Actually you can do:
> 
> 	int ret = 0;
> 
> 	pinmux_node = of_parse_phandle(node, "pinmux", 0);
> 	if (!pinmux_node)
> 		return -ENODEV;
> 
> 	pinmux_pdev = of_find_device_by_node(pinmux_node);
> 	/* We do not longer need pinmux node */
> 	of_node_put(pinmux_node);
> 
> 	if (!pinmux_dev)
> 		....
> 
> 	for (..) {
> 		...
> 		if (ret) {
> 			dev_err(...);
> 			break;
> 		}
> 	}
> 
> 	chip->pinmux_is_supported = (ret == 0);
> 	put_device(..);
> 	return ret;
> }
> 
> This way you free resources in the same path.
> 

Thanks. I'll make the change.

> ...
> 
>> +
>> +static struct platform_driver cygnus_gpio_driver = {
>> +	.driver = {
>> +		.name = "cygnus-gpio",
>> +		.of_match_table = cygnus_gpio_of_match,
>> +		.suppress_bind_attrs = true,
>> +	},
>> +	.probe = cygnus_gpio_probe,
>> +};
>> +
>> +static int __init cygnus_gpio_init(void)
>> +{
>> +	return platform_driver_probe(&cygnus_gpio_driver, cygnus_gpio_probe);
> 
> When I asked you to add ".suppress_bind_attrs = true" I missed the fact
> that you were using platform_driver_probe() which already does this
> internally. However platform_driver_probe() can't handle deferred
> probing, which may or may not be OK. Is there a chance that any of the
> resources needed by the driver return -EPROBE_DEFER? If not then it is
> safe to continue using platform_driver_probe() and you can drop
> suppress_bind_attrs assignment, otherwise it may be better to switch to
> platform_driver_register().
> 
> Thanks.
> 

No I do not expect any resource that this driver depends on to return
-EPROBE_DEFER. The IOMUX driver that this driver depends on should be
initialized before this driver.

I'll drop .suppress_bind_attrs then. Thanks.

Ray

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