linux-kernel - Re: [PATCH] mmc: mtk-sd: use div64_u64() instead of do

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Date:   Thu, 17 Feb 2022 16:39:48 +0100
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Qing Wang <wangqing@...o.com>
Cc:     Chaotian Jing <chaotian.jing@...iatek.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        linux-mmc@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mmc: mtk-sd: use div64_u64() instead of do_div()

On Wed, 9 Feb 2022 at 09:39, Qing Wang <wangqing@...o.com> wrote:
>
> From: Wang Qing <wangqing@...o.com>
>
> do_div() does a 64-by-32 division.
> When the divisor is u64, do_div() truncates it to 32 bits, this means it
> can test non-zero and be truncated to zero for division.
>
> fix do_div.cocci warning:
> do_div() does a 64-by-32 division, please consider using div64_u64 instead.
>
> Signed-off-by: Wang Qing <wangqing@...o.com>

Applied for next, thanks!

Kind regards
Uffe


> ---
>  drivers/mmc/host/mtk-sd.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/host/mtk-sd.c b/drivers/mmc/host/mtk-sd.c
> index 65037e1..777c9a8
> --- a/drivers/mmc/host/mtk-sd.c
> +++ b/drivers/mmc/host/mtk-sd.c
> @@ -766,7 +766,7 @@ static u64 msdc_timeout_cal(struct msdc_host *host, u64 ns, u64 clks)
>                 clk_ns  = 1000000000ULL;
>                 do_div(clk_ns, mmc->actual_clock);
>                 timeout = ns + clk_ns - 1;
> -               do_div(timeout, clk_ns);
> +               div64_u64(timeout, clk_ns);
>                 timeout += clks;
>                 /* in 1048576 sclk cycle unit */
>                 timeout = DIV_ROUND_UP(timeout, BIT(20));
> --
> 2.7.4
>