linux-kernel - Re: [PATCH v2 1/3] clk: k210: remove an implicit 64-bit division

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Message-ID: <Y+qSqHDhcFZNqOMg@spud>
Date:   Mon, 13 Feb 2023 19:42:32 +0000
From:   Conor Dooley <conor@...nel.org>
To:     Jesse Taube <mr.bossman075@...il.com>
Cc:     linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Yimin Gu <ustcymgu@...il.com>,
        Waldemar Brodkorb <wbx@...nadk.org>,
        Albert Ou <aou@...s.berkeley.edu>,
        Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Conor Dooley <conor.dooley@...rochip.com>,
        kernel test robot <lkp@...el.com>
Subject: Re: [PATCH v2 1/3] clk: k210: remove an implicit 64-bit division

On Sun, Feb 12, 2023 at 03:55:04PM -0500, Jesse Taube wrote:
> From: Conor Dooley <conor.dooley@...rochip.com>
> 
> The K210 clock driver depends on SOC_CANAAN, which is only selectable
> when !MMU on RISC-V. !MMU is not possible on 32-bit yet, but patches
> have been sent for its enabling. The kernel test robot reported this
> implicit 64-bit division there.
> 
> Replace the implicit division with an explicit one.
> 
> Reported-by: kernel test robot <lkp@...el.com>
> Link: https://lore.kernel.org/linux-riscv/202301201538.zNlqgE4L-lkp@intel.com/
> Signed-off-by: Conor Dooley <conor.dooley@...rochip.com>
> Signed-off-by: Jesse Taube <Mr.Bossman075@...il.com>

btw, you'll need to run get_maintainer.pl on this patch so that the k210
and clock maintainers are CCed.

It's also worth adding Damien Le Moal <damien.lemoal@....com>

> ---
>  drivers/clk/clk-k210.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/clk/clk-k210.c b/drivers/clk/clk-k210.c
> index 67a7cb3503c3..4eed667eddaf 100644
> --- a/drivers/clk/clk-k210.c
> +++ b/drivers/clk/clk-k210.c
> @@ -495,7 +495,7 @@ static unsigned long k210_pll_get_rate(struct clk_hw *hw,
>  	f = FIELD_GET(K210_PLL_CLKF, reg) + 1;
>  	od = FIELD_GET(K210_PLL_CLKOD, reg) + 1;
>  
> -	return (u64)parent_rate * f / (r * od);
> +	return div_u64((u64)parent_rate * f, r * od);
>  }
>  
>  static const struct clk_ops k210_pll_ops = {
> -- 
> 2.39.0
> 

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