linux-kernel - Re: [PATCH] clk: rockchip: Fix -Wunused-const-variable

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Message-ID: <CAKwvOd=RhoKvXzuGVe0PaQik8NEFhDkxuwv-T_s6KAtXCDVVvg@mail.gmail.com>
Date:   Thu, 27 Jun 2019 15:32:38 -0700
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     Nathan Huckleberry <nhuck@...gle.com>
Cc:     mturquette@...libre.com, sboyd@...nel.org, heiko@...ech.de,
        andy.yan@...k-chips.com, zhangqing@...k-chips.com,
        linux-clk@...r.kernel.org,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        linux-rockchip@...ts.infradead.org,
        LKML <linux-kernel@...r.kernel.org>,
        clang-built-linux <clang-built-linux@...glegroups.com>
Subject: Re: [PATCH] clk: rockchip: Fix -Wunused-const-variable

On Thu, Jun 27, 2019 at 3:22 PM 'Nathan Huckleberry' via Clang Built
Linux <clang-built-linux@...glegroups.com> wrote:
>
> Clang produces the following warning
>
> drivers/clk/rockchip/clk-rv1108.c:125:7: warning: unused variable
> 'mux_pll_src_3plls_p' [-Wunused-const-variable]
> PNAME(mux_pll_src_3plls_p)      = { "apll", "gpll", "dpll" };
>
> Looks like this variable was never used. Deleting it to remove the
> warning.

Indeed, looks like it was dead when introduced in:
commit e44dde279492 ("clk: rockchip: add clock controller for rk1108")

I don't see a pattern between when mux_pll_src_4plls_p vs
mux_pll_src_2plls_p is used, so it's not clear where or even if
mux_pll_src_3plls_p should be used.  Given that there hasn't been a
response to your original question
(https://groups.google.com/forum/#!topic/clang-built-linux/NqJT9OPH5C8)
and this patch is no functional change as the variable is already
dead, I don't think it will hurt to remove it.  It should also boost
the signal to noise ratio of this warning.

Thanks for looking into it, and the patch.
Reviewed-by: Nick Desaulniers <ndesaulniers@...gle.com>

> diff --git a/drivers/clk/rockchip/clk-rv1108.c b/drivers/clk/rockchip/clk-rv1108.c
> index 96cc6af5632c..5947d3192866 100644
> --- a/drivers/clk/rockchip/clk-rv1108.c
> +++ b/drivers/clk/rockchip/clk-rv1108.c
> @@ -122,7 +122,6 @@ PNAME(mux_usb480m_pre_p)    = { "usbphy", "xin24m" };
>  PNAME(mux_hdmiphy_phy_p)       = { "hdmiphy", "xin24m" };
>  PNAME(mux_dclk_hdmiphy_pre_p)  = { "dclk_hdmiphy_src_gpll", "dclk_hdmiphy_src_dpll" };
>  PNAME(mux_pll_src_4plls_p)     = { "dpll", "gpll", "hdmiphy", "usb480m" };
> -PNAME(mux_pll_src_3plls_p)     = { "apll", "gpll", "dpll" };

Thanks,
~Nick Desaulniers