linux-kernel - Re: [PATCH v2 2/2] NFC: Add ACPI support for NXP PN544

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Message-ID: <20150212081459.GA28954@pengutronix.de>
Date:	Thu, 12 Feb 2015 09:14:59 +0100
From:	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>
To:	Robert Dolca <robert.dolca@...el.com>
Cc:	linux-nfc@...1.01.org,
	Lauro Ramos Venancio <lauro.venancio@...nbossa.org>,
	Aloisio Almeida Jr <aloisio.almeida@...nbossa.org>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	linux-kernel@...r.kernel.org, linux-wireless@...r.kernel.org,
	netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
	Berg Johannes <johannes.berg@...el.com>,
	Clement Perrochaud <clement.perrochaud@....com>
Subject: Re: [PATCH v2 2/2] NFC: Add ACPI support for NXP PN544

Hello,

On Mon, Jan 26, 2015 at 01:13:37PM +0200, Robert Dolca wrote:
> +	/* Get EN GPIO from ACPI */
> +	gpiod_en = devm_gpiod_get_index(dev, PN544_GPIO_NAME_EN, 1);
Actually devm_gpiod_get_index takes 4 arguments. In your case you should
also pass GPIOD_OUT_LOW, then you can skip the gpiod_direction_output
part below.

> +	if (IS_ERR(gpiod_en)) {
> +		nfc_err(dev,
> +			"Unable to get EN GPIO\n");
> +		return -ENODEV;
> +	}
> +
> +	phy->gpio_en  = desc_to_gpio(gpiod_en);
Why don't you save a reference to the gpiod instead? Mixing usage of raw
and gpiod might result in surprising results. For example

	gpiod_direction_output(gpiod_en, 0);

might actually have the same result as

	gpio_direction_output(gpio_en, 1);

if the matching gpio is marked as active low.

> +
> +	/* Configuration EN GPIO */
> +	ret = gpiod_direction_output(gpiod_en, 0);
> +	if (ret) {
> +		nfc_err(dev, "Fail EN pin direction\n");
> +		return ret;
> +	}
> +
> +	/* Get FW GPIO from ACPI */
> +	gpiod_fw = devm_gpiod_get_index(dev, PN544_GPIO_NAME_FW, 2);
> +	if (IS_ERR(gpiod_fw)) {
> +		nfc_err(dev,
> +			"Unable to get FW GPIO\n");
> +		return -ENODEV;
> +	}
> +
> +	phy->gpio_fw  = desc_to_gpio(gpiod_fw);
> +
> +	/* Configuration FW GPIO */
> +	ret = gpiod_direction_output(gpiod_fw, 0);
> +	if (ret) {
> +		nfc_err(dev, "Fail FW pin direction\n");
> +		return ret;
> +	}
The same comments apply here.

> +
> +	/* Get IRQ GPIO */
> +	gpiod_irq = devm_gpiod_get_index(dev, PN544_GPIO_NAME_IRQ, 0);
> +	if (IS_ERR(gpiod_irq)) {
> +		nfc_err(dev,
> +			"Unable to get IRQ GPIO\n");
> +		return -ENODEV;
> +	}
> +
> +	phy->gpio_irq = desc_to_gpio(gpiod_irq);
> +
> +	/* Configure IRQ GPIO */
> +	ret = gpiod_direction_input(gpiod_irq);
> +	if (ret) {
> +		nfc_err(dev, "Fail IRQ pin direction\n");
> +		return ret;
> +	}
> +
> +	/* Map the pin to an IRQ */
> +	ret = gpiod_to_irq(gpiod_irq);
> +	if (ret < 0) {
> +		nfc_err(dev, "Fail pin IRQ mapping\n");
> +		return ret;
> +	}
and here.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
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