linux-kernel - Re: [PATCH] clk: renesas: r8a7778: remove checker warnings: x

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Message-ID: <CAMuHMdUhp7AntSk1ZnTowiEC6XibR1im_7OKdF2JDg=51ewsyw@mail.gmail.com>
Date:   Tue, 13 Jun 2023 09:39:36 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     "GONG, Ruiqi" <gongruiqi@...weicloud.com>
Cc:     Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        linux-renesas-soc@...r.kernel.org, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org, gongruiqi1@...wei.com,
        linux-sparse@...r.kernel.org
Subject: Re: [PATCH] clk: renesas: r8a7778: remove checker warnings: x | !y

Hi Gong,

On Tue, Jun 13, 2023 at 4:50 AM GONG, Ruiqi <gongruiqi@...weicloud.com> wrote:
> Eliminate the following Sparse reports when building with C=1:
>
> drivers/clk/renesas/clk-r8a7778.c:85:52: warning: dubious: x | !y
> drivers/clk/renesas/clk-r8a7778.c:87:50: warning: dubious: x | !y
>
> Signed-off-by: GONG, Ruiqi <gongruiqi@...weicloud.com>

Thanks for your patch!

Looks like sparse needs to be taught the "|" is not used in a boolean
context here?

See also
https://lore.kernel.org/r/CAMuHMdXGG2xu+nXJt6CSTfV6aM=U=hMW+DiDgP3RhOw8+O8y=A@mail.gmail.com

> --- a/drivers/clk/renesas/clk-r8a7778.c
> +++ b/drivers/clk/renesas/clk-r8a7778.c
> @@ -81,11 +81,11 @@ static void __init r8a7778_cpg_clocks_init(struct device_node *np)
>
>         BUG_ON(!(mode & BIT(19)));
>
> -       cpg_mode_rates = (!!(mode & BIT(18)) << 2) |
> -                        (!!(mode & BIT(12)) << 1) |
> -                        (!!(mode & BIT(11)));
> -       cpg_mode_divs = (!!(mode & BIT(2)) << 1) |
> -                       (!!(mode & BIT(1)));
> +       cpg_mode_rates = (mode & BIT(18) ? BIT(2) : 0) |
> +                        (mode & BIT(12) ? BIT(1) : 0) |
> +                        (mode & BIT(11) ? BIT(0) : 0);
> +       cpg_mode_divs = (mode & BIT(2) ? BIT(1) : 0) |
> +                       (mode & BIT(1) ? BIT(0) : 0);
>
>         num_clks = of_property_count_strings(np, "clock-output-names");
>         if (num_clks < 0) {

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds