linux-kernel - Re: [next] i2c: mediatek: Use div_u64 for 64-bit division to fix 32-bit kernels

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Date:   Wed, 20 May 2020 09:15:03 -0700
From:   Randy Dunlap <rdunlap@...radead.org>
To:     qii.wang@...iatek.com, wsa@...-dreams.de
Cc:     linux-i2c@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-mediatek@...ts.infradead.org, srv_heupstream@...iatek.com,
        leilk.liu@...iatek.com
Subject: Re: [next] i2c: mediatek: Use div_u64 for 64-bit division to fix
 32-bit kernels

On 5/20/20 3:31 AM, qii.wang@...iatek.com wrote:
> From: Qii Wang <qii.wang@...iatek.com>
> 
> Use div_u64 for 64-bit division, and change sample_ns type to
> unsigned int. Otherwise, the module will reference __udivdi3
> under 32-bit kernels, which is not allowed in kernel space.
> 
> Signed-off-by: Qii Wang <qii.wang@...iatek.com>

Acked-by: Randy Dunlap <rdunlap@...radead.org> # build-tested

thanks.

> ---
>  drivers/i2c/busses/i2c-mt65xx.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/i2c/busses/i2c-mt65xx.c b/drivers/i2c/busses/i2c-mt65xx.c
> index 7020618..deef69e 100644
> --- a/drivers/i2c/busses/i2c-mt65xx.c
> +++ b/drivers/i2c/busses/i2c-mt65xx.c
> @@ -551,7 +551,8 @@ static int mtk_i2c_check_ac_timing(struct mtk_i2c *i2c,
>  	const struct i2c_spec_values *spec;
>  	unsigned int su_sta_cnt, low_cnt, high_cnt, max_step_cnt;
>  	unsigned int sda_max, sda_min, clk_ns, max_sta_cnt = 0x3f;
> -	long long sample_ns = (1000000000 * (sample_cnt + 1)) / clk_src;
> +	unsigned int sample_ns = div_u64(1000000000ULL * (sample_cnt + 1),
> +					 clk_src);
>  
>  	if (!i2c->dev_comp->timing_adjust)
>  		return 0;
> 


-- 
~Randy