gpio: rockchip: resolve overflow issues

[PATCH v2] gpio: rockchip: resolve overflow issues

Posted by Ye Zhang 1 year, 5 months ago

Prevent overflow issues when performing debounce-related calculations.

Fixes: 3bcbd1a85b68 ("gpio/rockchip: support next version gpio controller")
Signed-off-by: Ye Zhang <ye.zhang@rock-chips.com>
---
 drivers/gpio/gpio-rockchip.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpio/gpio-rockchip.c b/drivers/gpio/gpio-rockchip.c
index 5f60162baaeb..bf22b103b6a2 100644
--- a/drivers/gpio/gpio-rockchip.c
+++ b/drivers/gpio/gpio-rockchip.c
@@ -209,11 +209,12 @@ static int rockchip_gpio_set_debounce(struct gpio_chip *gc,
 		freq = clk_get_rate(bank->db_clk);
 		if (!freq)
 			return -EINVAL;
-		max_debounce = (GENMASK(23, 0) + 1) * 2 * 1000000 / freq;
+		div = (u64)(GENMASK(23, 0) + 1) * 2 * 1000000;
+		max_debounce = DIV_ROUND_CLOSEST_ULL(div, freq);
 		if (debounce > max_debounce)
 			return -EINVAL;
 
-		div = debounce * freq;
+		div = (u64)debounce * freq;
 		div_reg = DIV_ROUND_CLOSEST_ULL(div, 2 * USEC_PER_SEC) - 1;
 	} else {
 		div_debounce_support = false;
-- 
2.34.1

Re: [PATCH v2] gpio: rockchip: resolve overflow issues

Posted by Andy Shevchenko 1 year, 5 months ago

On Fri, Aug 23, 2024 at 11:43:06AM +0800, Ye Zhang wrote:
> Prevent overflow issues when performing debounce-related calculations.

...

> -		max_debounce = (GENMASK(23, 0) + 1) * 2 * 1000000 / freq;
> +		div = (u64)(GENMASK(23, 0) + 1) * 2 * 1000000;

You probably want to use HZ_PER_MHZ from units.h or so?

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v2] gpio: rockchip: resolve overflow issues

Posted by Shawn Lin 1 year, 5 months ago

在 2024/8/23 11:43, Ye Zhang 写道:
> Prevent overflow issues when performing debounce-related calculations.
> 
> Fixes: 3bcbd1a85b68 ("gpio/rockchip: support next version gpio controller")
> Signed-off-by: Ye Zhang <ye.zhang@rock-chips.com>
> ---
>   drivers/gpio/gpio-rockchip.c | 5 +++--
>   1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpio/gpio-rockchip.c b/drivers/gpio/gpio-rockchip.c
> index 5f60162baaeb..bf22b103b6a2 100644
> --- a/drivers/gpio/gpio-rockchip.c
> +++ b/drivers/gpio/gpio-rockchip.c
> @@ -209,11 +209,12 @@ static int rockchip_gpio_set_debounce(struct gpio_chip *gc,
>   		freq = clk_get_rate(bank->db_clk);
>   		if (!freq)
>   			return -EINVAL;
> -		max_debounce = (GENMASK(23, 0) + 1) * 2 * 1000000 / freq;
> +		div = (u64)(GENMASK(23, 0) + 1) * 2 * 1000000;
> +		max_debounce = DIV_ROUND_CLOSEST_ULL(div, freq);

can't max_debounce = DIV_ROUND_CLOSEST_ULL((GENMASK(23, 0) + 1) * 2 *
1000000, freq) work?

>   		if (debounce > max_debounce)
>   			return -EINVAL;
>   
> -		div = debounce * freq;
> +		div = (u64)debounce * freq;
>   		div_reg = DIV_ROUND_CLOSEST_ULL(div, 2 * USEC_PER_SEC) - 1;
>   	} else {
>   		div_debounce_support = false;

Re: [PATCH v2] gpio: rockchip: resolve overflow issues

Posted by Andy Shevchenko 1 year, 5 months ago

On Fri, Aug 23, 2024 at 06:59:40PM +0800, Shawn Lin wrote:
> 在 2024/8/23 11:43, Ye Zhang 写道:

...

> > -		max_debounce = (GENMASK(23, 0) + 1) * 2 * 1000000 / freq;
> > +		div = (u64)(GENMASK(23, 0) + 1) * 2 * 1000000;
> > +		max_debounce = DIV_ROUND_CLOSEST_ULL(div, freq);
> 
> can't max_debounce = DIV_ROUND_CLOSEST_ULL((GENMASK(23, 0) + 1) * 2 *
> 1000000, freq) work?

Wouldn't be too long line in this case?

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v2] gpio: rockchip: resolve overflow issues

Posted by Heiko Stübner 1 year, 5 months ago

Am Freitag, 23. August 2024, 05:43:06 CEST schrieb Ye Zhang:
> Prevent overflow issues when performing debounce-related calculations.

Please add some more explanation here.
I.e. something about previous max_debounce calculation does overflow
the type of max_debounce

Thanks
Heiko

> Fixes: 3bcbd1a85b68 ("gpio/rockchip: support next version gpio controller")
> Signed-off-by: Ye Zhang <ye.zhang@rock-chips.com>
> ---
>  drivers/gpio/gpio-rockchip.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpio/gpio-rockchip.c b/drivers/gpio/gpio-rockchip.c
> index 5f60162baaeb..bf22b103b6a2 100644
> --- a/drivers/gpio/gpio-rockchip.c
> +++ b/drivers/gpio/gpio-rockchip.c
> @@ -209,11 +209,12 @@ static int rockchip_gpio_set_debounce(struct gpio_chip *gc,
>  		freq = clk_get_rate(bank->db_clk);
>  		if (!freq)
>  			return -EINVAL;
> -		max_debounce = (GENMASK(23, 0) + 1) * 2 * 1000000 / freq;
> +		div = (u64)(GENMASK(23, 0) + 1) * 2 * 1000000;
> +		max_debounce = DIV_ROUND_CLOSEST_ULL(div, freq);
>  		if (debounce > max_debounce)
>  			return -EINVAL;
>  
> -		div = debounce * freq;
> +		div = (u64)debounce * freq;
>  		div_reg = DIV_ROUND_CLOSEST_ULL(div, 2 * USEC_PER_SEC) - 1;
>  	} else {
>  		div_debounce_support = false;
>