Message-ID: <54DA7C79.2010606@broadcom.com>
Date: Tue, 10 Feb 2015 13:47:37 -0800
From: Ray Jui <rjui@broadcom.com>
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To: Dmitry Torokhov <dtor@chromium.org>
CC: Linus Walleij <linus.walleij@linaro.org>,
        Alexandre Courbot <gnurou@gmail.com>, Rob Herring <robh+dt@kernel.org>,
        Pawel Moll <pawel.moll@arm.com>, Mark Rutland <mark.rutland@arm.com>,
        Ian Campbell <ijc+devicetree@hellion.org.uk>,
        Kumar Gala <galak@codeaurora.org>,
        "Grant Likely" <grant.likely@linaro.org>,
        Christian Daudt <bcm@fixthebug.org>, Matt Porter <mporter@linaro.org>,
        Florian Fainelli <f.fainelli@gmail.com>,
        Russell King <linux@arm.linux.org.uk>, Joe Perches <joe@perches.com>,
        "Arnd Bergmann" <arnd@arndb.de>, Scott Branden <sbranden@broadcom.com>,
        "Anatol Pomazau" <anatol@google.com>, <linux-kernel@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>, <linux-gpio@vger.kernel.org>,
        <bcm-kernel-feedback-list@broadcom.com>, <devicetree@vger.kernel.org>
Subject: Re: [PATCH v8 2/4] pinctrl: cygnus: add gpio/pinconf driver
References: <rjui@broadcom.com> <1423070463-24483-1-git-send-email-rjui@broadcom.com> <1423070463-24483-3-git-send-email-rjui@broadcom.com> <20150209191951.GA15709@dtor-ws>
In-Reply-To: <20150209191951.GA15709@dtor-ws>
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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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