Re: [PATCH v2] clk: hisilicon: Remove unnecessary local variable

From: Uwe Kleine-König
Date: Thu Aug 01 2024 - 13:18:23 EST


Hello,

On Thu, Aug 01, 2024 at 12:36:16PM +0200, Thorsten Blum wrote:
> The local u64 variable refdiv_val has the same value as the local u32
> variable val and can be removed. Remove it and use val directly as the
> divisor to also remove the following Coccinelle/coccicheck warning
> reported by do_div.cocci:
>
> WARNING: do_div() does a 64-by-32 division, please consider using div64_u64 instead
>
> Use the preferred div_u64() function instead of the do_div() macro.
>
> Signed-off-by: Thorsten Blum <thorsten.blum@xxxxxxxxxx>
> ---
> Changes in v2:
> - Use div_u64() instead of do_div() as suggested by Stephen Boyd
> - Link to v1: https://lore.kernel.org/linux-kernel/20240710201844.710365-2-thorsten.blum@xxxxxxxxxx/
> ---
> drivers/clk/hisilicon/clk-hi3559a.c | 7 +++----
> 1 file changed, 3 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/clk/hisilicon/clk-hi3559a.c b/drivers/clk/hisilicon/clk-hi3559a.c
> index c79a94f6d9d2..8646e9d352ed 100644
> --- a/drivers/clk/hisilicon/clk-hi3559a.c
> +++ b/drivers/clk/hisilicon/clk-hi3559a.c
> @@ -407,7 +407,7 @@ static unsigned long clk_pll_recalc_rate(struct clk_hw *hw,
> unsigned long parent_rate)
> {
> struct hi3559av100_clk_pll *clk = to_pll_clk(hw);
> - u64 frac_val, fbdiv_val, refdiv_val;
> + u64 frac_val, fbdiv_val;
> u32 postdiv1_val, postdiv2_val;
> u32 val;
> u64 tmp, rate;
> @@ -435,14 +435,13 @@ static unsigned long clk_pll_recalc_rate(struct clk_hw *hw,
> val = readl_relaxed(clk->ctrl_reg2);
> val = val >> clk->refdiv_shift;
> val &= ((1 << clk->refdiv_width) - 1);
> - refdiv_val = val;
>
> /* rate = 24000000 * (fbdiv + frac / (1<<24) ) / refdiv */
> rate = 0;
> tmp = 24000000 * fbdiv_val + (24000000 * frac_val) / (1 << 24);
> rate += tmp;
> - do_div(rate, refdiv_val);
> - do_div(rate, postdiv1_val * postdiv2_val);
> + rate = div_u64(rate, val);
> + rate = div_u64(rate, postdiv1_val * postdiv2_val);

Without looking at the bigger context: Can postdiv1_val * postdiv2_val
overflow? (If this is a problem, fixing it justifies another patch, so
this concern shouldn't stop this patch from being accepted.)

Otherwise looks fine,
Acked-by: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxx>

Best regards
Uwe

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