gpio: rockchip: resolve underflow issue

[PATCH v2] gpio: rockchip: resolve underflow issue

Posted by Ye Zhang 1 year, 5 months ago

div_reg may be < 0 if debounce is zero, causing the unsigned int to
overflow.

Fixes: 3bcbd1a85b68 ("gpio/rockchip: support next version gpio controller")
Signed-off-by: Ye Zhang <ye.zhang@rock-chips.com>
---
 drivers/gpio/gpio-rockchip.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/gpio/gpio-rockchip.c b/drivers/gpio/gpio-rockchip.c
index bf22b103b6a2..c3a87d075908 100644
--- a/drivers/gpio/gpio-rockchip.c
+++ b/drivers/gpio/gpio-rockchip.c
@@ -204,8 +204,8 @@ static int rockchip_gpio_set_debounce(struct gpio_chip *gc,
 	unsigned int cur_div_reg;
 	u64 div;
 
-	if (bank->gpio_type == GPIO_TYPE_V2 && !IS_ERR(bank->db_clk)) {
-		div_debounce_support = true;
+	div_debounce_support = (bank->gpio_type == GPIO_TYPE_V2) && !IS_ERR(bank->db_clk);
+	if (debounce && div_debounce_support) {
 		freq = clk_get_rate(bank->db_clk);
 		if (!freq)
 			return -EINVAL;
@@ -216,8 +216,6 @@ static int rockchip_gpio_set_debounce(struct gpio_chip *gc,
 
 		div = (u64)debounce * freq;
 		div_reg = DIV_ROUND_CLOSEST_ULL(div, 2 * USEC_PER_SEC) - 1;
-	} else {
-		div_debounce_support = false;
 	}
 
 	raw_spin_lock_irqsave(&bank->slock, flags);
-- 
2.34.1

Re: [PATCH v2] gpio: rockchip: resolve underflow issue

Posted by Andy Shevchenko 1 year, 5 months ago

On Fri, Aug 23, 2024 at 11:43:07AM +0800, Ye Zhang wrote:
> div_reg may be < 0 if debounce is zero, causing the unsigned int to
> overflow.

...

> -	if (bank->gpio_type == GPIO_TYPE_V2 && !IS_ERR(bank->db_clk)) {
> -		div_debounce_support = true;

Wouldn't be cleaner (from the patch perspective) to simply move else branch here?

	else
		div_debounce_support = false;

> +	div_debounce_support = (bank->gpio_type == GPIO_TYPE_V2) && !IS_ERR(bank->db_clk);
> +	if (debounce && div_debounce_support) {
>  		freq = clk_get_rate(bank->db_clk);
>  		if (!freq)
>  			return -EINVAL;
> @@ -216,8 +216,6 @@ static int rockchip_gpio_set_debounce(struct gpio_chip *gc,
>  
>  		div = (u64)debounce * freq;
>  		div_reg = DIV_ROUND_CLOSEST_ULL(div, 2 * USEC_PER_SEC) - 1;
> -	} else {
> -		div_debounce_support = false;
>  	}

-- 
With Best Regards,
Andy Shevchenko