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Commit 83977443 authored by David Rivshin's avatar David Rivshin Committed by Linus Walleij
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gpio: omap: return error if requested debounce time is not possible 



omap_gpio_debounce() does not validate that the requested debounce
is within a range it can handle. Instead it lets the register value
wrap silently, and always returns success.

This can lead to all sorts of unexpected behavior, such as gpio_keys
asking for a too-long debounce, but getting a very short debounce in
practice.

Fix this by returning -EINVAL if the requested value does not fit into
the register field. If there is no debounce clock available at all,
return -ENOTSUPP.

Fixes: e85ec6c3 ("gpio: omap: fix omap2_set_gpio_debounce")
Cc: <stable@vger.kernel.org> # 4.3+
Signed-off-by: default avatarDavid Rivshin <drivshin@allworx.com>
Acked-by: default avatarGrygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
parent 93847930

drivers/gpio/gpio-omap.c

+17 −6
Original line number Diff line number Diff line
@@ -208,8 +208,10 @@ static inline void omap_gpio_dbck_disable(struct gpio_bank *bank) 
 * OMAP's debounce time is in 31us steps

 *   <debounce time> = (GPIO_DEBOUNCINGTIME[7:0].DEBOUNCETIME + 1) x 31

 * so we need to convert and round up to the closest unit.

 *

 * Return: 0 on success, negative error otherwise.

 */

static void omap2_set_gpio_debounce(struct gpio_bank *bank, unsigned offset,

static int omap2_set_gpio_debounce(struct gpio_bank *bank, unsigned offset,

				   unsigned debounce)

{

	void __iomem		*reg;
@@ -218,11 +220,12 @@ static void omap2_set_gpio_debounce(struct gpio_bank *bank, unsigned offset, 
	bool			enable = !!debounce;



	if (!bank->dbck_flag)

		return;

		return -ENOTSUPP;



	if (enable) {

		debounce = DIV_ROUND_UP(debounce, 31) - 1;

		debounce &= OMAP4_GPIO_DEBOUNCINGTIME_MASK;

		if ((debounce & OMAP4_GPIO_DEBOUNCINGTIME_MASK) != debounce)

			return -EINVAL;

	}



	l = BIT(offset);
@@ -255,6 +258,8 @@ static void omap2_set_gpio_debounce(struct gpio_bank *bank, unsigned offset, 
		bank->context.debounce = debounce;

		bank->context.debounce_en = val;

	}



	return 0;

}



/**
@@ -964,14 +969,20 @@ static int omap_gpio_debounce(struct gpio_chip *chip, unsigned offset, 
{

	struct gpio_bank *bank;

	unsigned long flags;

	int ret;



	bank = gpiochip_get_data(chip);



	raw_spin_lock_irqsave(&bank->lock, flags);

	omap2_set_gpio_debounce(bank, offset, debounce);

	ret = omap2_set_gpio_debounce(bank, offset, debounce);

	raw_spin_unlock_irqrestore(&bank->lock, flags);



	return 0;

	if (ret)

		dev_info(chip->parent,

			 "Could not set line %u debounce to %u microseconds (%d)",

			 offset, debounce, ret);



	return ret;

}



static int omap_gpio_set_config(struct gpio_chip *chip, unsigned offset,