linux-kernel - Re: [PATCH v2] gpio: rockchip: resolve overflow issues

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Message-ID: <f2194489-c637-4034-9077-951f74d621a5@rock-chips.com>
Date: Fri, 23 Aug 2024 18:59:40 +0800
From: Shawn Lin <shawn.lin@...k-chips.com>
To: Ye Zhang <ye.zhang@...k-chips.com>, linus.walleij@...aro.org,
 brgl@...ev.pl, heiko@...ech.de, linux-gpio@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org
Cc: shawn.lin@...k-chips.com, linux-rockchip@...ts.infradead.org,
 linux-kernel@...r.kernel.org, mika.westerberg@...ux.intel.com,
 andriy.shevchenko@...ux.intel.com, tao.huang@...k-chips.com,
 finley.xiao@...k-chips.com, tim.chen@...k-chips.com,
 elaine.zhang@...k-chips.com
Subject: Re: [PATCH v2] gpio: rockchip: resolve overflow issues

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@...k-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;