linux-kernel - Re: [PATCH v5 2/5] x86/platform: (TS-5500) add GPIO support

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Message-ID: <20120206151614.GD10173@sirena.org.uk>
Date:	Mon, 6 Feb 2012 15:16:14 +0000
From:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
To:	Vivien Didelot <vivien.didelot@...oirfairelinux.com>
Cc:	x86@...nel.org,
	Jerome Oufella <jerome.oufella@...oirfairelinux.com>,
	Ingo Molnar <mingo@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org,
	lm-sensors@...sensors.org,
	Guenter Roeck <guenter.roeck@...csson.com>,
	Jean Delvare <khali@...ux-fr.org>
Subject: Re: [PATCH v5 2/5] x86/platform: (TS-5500) add GPIO support

On Wed, Feb 01, 2012 at 04:05:41PM -0500, Vivien Didelot wrote:

>  arch/x86/platform/ts5500/Kconfig       |    7 +
>  arch/x86/platform/ts5500/Makefile      |    1 +
>  arch/x86/platform/ts5500/ts5500_gpio.c |  478 ++++++++++++++++++++++++++++++++
>  arch/x86/platform/ts5500/ts5500_gpio.h |   60 ++++

As previously pointed out rather than hiding these drivers in arch/
directories there's a push to ship them in drivers/ where they benefit
from better subsystem review.

> +static int ts5500_gpio_request(struct gpio_chip *chip, unsigned offset)
> +{
> +	struct ts5500_drvdata *drvdata;
> +
> +	drvdata = container_of(chip, struct ts5500_drvdata, gpio_chip);
> +
> +	mutex_lock(&drvdata->gpio_lock);
> +	if (requested_gpios[offset]) {
> +		mutex_unlock(&drvdata->gpio_lock);
> +		return -EBUSY;
> +	}
> +	requested_gpios[offset] = 1;
> +	mutex_unlock(&drvdata->gpio_lock);

This is all redundant, gpiolib will check this for you.

> +static void ts5500_gpio_set(struct gpio_chip *chip, unsigned offset, int val)
> +{

This (and get()) should be a _cansleep() operation because...

> +	mutex_lock(&drvdata->gpio_lock);
> +	if (val == 0)
> +		port_bit_clear(ioaddr, bitno);
> +	else
> +		port_bit_set(ioaddr, bitno);
> +	mutex_unlock(&drvdata->gpio_lock);

...you take a mutex which needs process context.

> +static int ts5500_gpio_to_irq(struct gpio_chip *chip, unsigned offset)
> +{
> +	/* Only a few lines are IRQ-Capable */
> +	switch (offset) {
> +	case TS5500_DIO1_13:
> +		return TS5500_DIO1_13_IRQ;
> +	case TS5500_DIO2_13:
> +		return TS5500_DIO2_13_IRQ;
> +	case TS5500_LCD_RS:
> +		return TS5500_LCD_RS_IRQ;

Why are these numbers compile time constants?

> +	/* Setup the gpio_chip structure */
> +	drvdata = kzalloc(sizeof(struct ts5500_drvdata), GFP_KERNEL);
> +	if (drvdata == NULL)
> +		goto err_alloc_dev;

Looks like you'd benefit from using devm_ functions for most if not all
of the allocation.

> +/* Callback for releasing resources */
> +static void ts5500_gpio_device_release(struct device *dev)
> +{
> +	/* noop */
> +}
> +
> +static struct platform_device ts5500_gpio_device = {
> +	.name = "ts5500_gpio",
> +	.id = -1,
> +	.dev = {
> +		.release = ts5500_gpio_device_release,
> +	}
> +};

I'm not sure what this is all about but it looks fairly obviously wrong.

> +static int __devexit ts5500_gpio_remove(struct platform_device *pdev)
> +{
> +	struct ts5500_drvdata *drvdata;
> +	int ret, i;
> +
> +	drvdata = platform_get_drvdata(pdev);
> +
> +	/* Release GPIO lines */
> +	for (i = 0; i < ARRAY_SIZE(requested_gpios); i++) {
> +		if (requested_gpios[i])
> +			gpio_free(i);
> +	}

You shouldn't be doing this, if it was sensible then gpiolib ought to be
doing it for you.
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