linux-kernel - Re: [PATCH v2] clk: imx: Use div64_ul instead of do

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Date:   Mon, 22 Nov 2021 15:27:14 +0200
From:   Abel Vesa <abel.vesa@....com>
To:     cgel.zte@...il.com
Cc:     festevam@...il.com, kernel@...gutronix.de,
        linux-arm-kernel@...ts.infradead.org, linux-clk@...r.kernel.org,
        linux-imx@....com, linux-kernel@...r.kernel.org,
        mturquette@...libre.com, s.hauer@...gutronix.de, sboyd@...nel.org,
        shawnguo@...nel.org, zealci@....com.cn, deng.changcheng@....com.cn
Subject: Re: [PATCH v2] clk: imx: Use div64_ul instead of do_div

On 21-11-18 08:06:34, cgel.zte@...il.com wrote:
> From: Changcheng Deng <deng.changcheng@....com.cn>
> 
> do_div() does a 64-by-32 division. Here the divisor is an unsigned long
> which on some platforms is 64 bit wide. So use div64_ul instead of do_div
> to avoid a possible truncation.
> 
> Reported-by: Zeal Robot <zealci@....com.cn>
> Signed-off-by: Changcheng Deng <deng.changcheng@....com.cn>

Reviewed-by: Abel Vesa <abel.vesa@....com>

> ---
>  drivers/clk/imx/clk-pllv3.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/clk/imx/clk-pllv3.c b/drivers/clk/imx/clk-pllv3.c
> index 20ee9611ba6e..55497e0585a6 100644
> --- a/drivers/clk/imx/clk-pllv3.c
> +++ b/drivers/clk/imx/clk-pllv3.c
> @@ -247,7 +247,7 @@ static long clk_pllv3_av_round_rate(struct clk_hw *hw, unsigned long rate,
>  	div = rate / parent_rate;
>  	temp64 = (u64) (rate - div * parent_rate);
>  	temp64 *= mfd;
> -	do_div(temp64, parent_rate);
> +	temp64 = div64_ul(temp64, parent_rate);
>  	mfn = temp64;
>  
>  	temp64 = (u64)parent_rate;
> @@ -277,7 +277,7 @@ static int clk_pllv3_av_set_rate(struct clk_hw *hw, unsigned long rate,
>  	div = rate / parent_rate;
>  	temp64 = (u64) (rate - div * parent_rate);
>  	temp64 *= mfd;
> -	do_div(temp64, parent_rate);
> +	temp64 = div64_ul(temp64, parent_rate);
>  	mfn = temp64;
>  
>  	val = readl_relaxed(pll->base);
> @@ -334,7 +334,7 @@ static struct clk_pllv3_vf610_mf clk_pllv3_vf610_rate_to_mf(
>  		/* rate = parent_rate * (mfi + mfn/mfd) */
>  		temp64 = rate - parent_rate * mf.mfi;
>  		temp64 *= mf.mfd;
> -		do_div(temp64, parent_rate);
> +		temp64 = div64_ul(temp64, parent_rate);
>  		mf.mfn = temp64;
>  	}
>  
> -- 
> 2.25.1
>