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References: <20220113115745.45826-1-liang.yang@amlogic.com> <20220113115745.45826-5-liang.yang@amlogic.com> <20220113213513.9819AC36AEA@smtp.kernel.org> <09ff9044-9abc-d1ad-26c1-5e6ece56d30c@amlogic.com> <20220114230130.35EAAC36AE7@smtp.kernel.org> <fe77fd6b-788f-1694-f260-f95e54cf4ef3@amlogic.com>
Subject: Re: [PATCH v9 4/4] clk: meson: add sub MMC clock controller driver
From:   Stephen Boyd <sboyd@kernel.org>
Cc:     Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
        Jianxin Pan <jianxin.pan@amlogic.com>,
        Victor Wan <victor.wan@amlogic.com>,
        XianWei Zhao <xianwei.zhao@amlogic.com>,
        Kelvin Zhang <kelvin.zhang@amlogic.com>,
        BiChao Zheng <bichao.zheng@amlogic.com>,
        YongHui Yu <yonghui.yu@amlogic.com>,
        linux-arm-kernel@lists.infradead.org,
        linux-amlogic@lists.infradead.org, linux-kernel@vger.kernel.org
To:     Jerome Brunet <jbrunet@baylibre.com>,
        Kevin Hilman <khilman@baylibre.com>,
        Liang Yang <liang.yang@amlogic.com>,
        Michael Turquette <mturquette@baylibre.com>,
        Neil Armstrong <narmstrong@baylibre.com>,
        Rob Herring <robh+dt@kernel.org>, linux-clk@vger.kernel.org
Date:   Tue, 18 Jan 2022 18:22:19 -0800
User-Agent: alot/0.10
Message-Id: <20220119022221.3AF83C340E0@smtp.kernel.org>
Precedence: bulk

Quoting Liang Yang (2022-01-16 22:24:28)
>=20
>=20
> On 2022/1/15 7:01, Stephen Boyd wrote:
> > [ EXTERNAL EMAIL ]
> >=20
> > Quoting Liang Yang (2022-01-13 21:14:46)
> >> On 2022/1/14 5:35, Stephen Boyd wrote:
> >>> Quoting Liang Yang (2022-01-13 03:57:45)
> >>>> diff --git a/drivers/clk/meson/mmc-clkc.c b/drivers/clk/meson/mmc-cl=
kc.c
> >>>> new file mode 100644
> >>>> index 000000000000..f53977f61390
> >>>> --- /dev/null
> >>>> +++ b/drivers/clk/meson/mmc-clkc.c
> >>>> @@ -0,0 +1,300 @@
> > [..]
> >>>> +
> >>>> +static int mmc_clkc_probe(struct platform_device *pdev)
> >>>> +{
> >>>> +       struct clk_hw_onecell_data *onecell_data;
> >>>> +       struct device *dev =3D &pdev->dev;
> >>>> +       struct mmc_clkc_data *data;
> >>>> +       struct regmap *map;
> >>>> +       struct clk_regmap *clk, *core;
> >>>> +       struct meson_sclk_div_data *div_data;
> >>>> +
> >>>> +       /*cast to drop the const in match->data*/
> >>>
> >>> Space after *, also why do we need to cast away const? The user of th=
is
> >>> pointer passes it all the way down to mmc_clkc_register_clk() which
> >>> could take the data as const void pointer and decide to cast away con=
st
> >>> there.
> >>
> >> if use 'const' here, it  will report a warning:
> >> drivers/clk/meson/mmc-clkc.c:224:7: error: assignment discards =E2=80=
=98const=E2=80=99
> >> qualifier from pointer targe
> >> t type [-Werror=3Ddiscarded-qualifiers]
> >>
> >>     data =3D (const struct mmc_clkc_data *)of_device_get_match_data(de=
v);
> >=20
> > Of course. The type declaration up above needs const added to it.The pa=
rm of mmc_clkc_register_clk_with_parent(...., void *data) does not=20
> have 'const', so make the type declaration cause a further 'const' cast=20
> warning. Could i copy these infos just like below:

Why can't you push const down to the function that really cares to
remove const?