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Subject: Re: [PATCH V2 2/2] clk: imx8m: check mcore_booted before register clk
From:   Stephen Boyd <sboyd@kernel.org>
Cc:     kernel@pengutronix.de, festevam@gmail.com, linux-imx@nxp.com,
        linux-clk@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org, Peng Fan <peng.fan@nxp.com>
To:     Peng Fan (OSS) <peng.fan@oss.nxp.com>, abel.vesa@nxp.com,
        s.hauer@pengutronix.de, shawnguo@kernel.org
Date:   Thu, 17 Mar 2022 12:38:13 -0700
User-Agent: alot/0.10
Message-Id: <20220317193815.47BC1C340E9@smtp.kernel.org>
Precedence: bulk

Quoting Peng Fan (OSS) (2022-02-28 04:41:12)
> From: Peng Fan <peng.fan@nxp.com>
>=20
> If mcore_booted is true, ignore the clk root gate registration and
> this will simplify AMP clock management and avoid system hang unexpectly
> especially Linux shutdown clk used by mcore.
>=20
> Signed-off-by: Peng Fan <peng.fan@nxp.com>
> ---
>=20
> V2:
>  None
>=20
>  drivers/clk/imx/clk-composite-8m.c | 21 +++++++++++++--------
>  1 file changed, 13 insertions(+), 8 deletions(-)
>=20
> diff --git a/drivers/clk/imx/clk-composite-8m.c b/drivers/clk/imx/clk-com=
posite-8m.c
> index 2dfd6149e528..b16c2c0ea9f6 100644
> --- a/drivers/clk/imx/clk-composite-8m.c
> +++ b/drivers/clk/imx/clk-composite-8m.c
> @@ -223,14 +223,19 @@ struct clk_hw *__imx8m_clk_hw_composite(const char =
*name,
>         div->lock =3D &imx_ccm_lock;
>         div->flags =3D CLK_DIVIDER_ROUND_CLOSEST;
> =20
> -       gate =3D kzalloc(sizeof(*gate), GFP_KERNEL);
> -       if (!gate)
> -               goto fail;
> -
> -       gate_hw =3D &gate->hw;
> -       gate->reg =3D reg;
> -       gate->bit_idx =3D PCG_CGC_SHIFT;
> -       gate->lock =3D &imx_ccm_lock;
> +       /* skip registering the gate ops if M4 is enabled */
> +       if (mcore_booted) {
> +               gate_hw =3D NULL;

It could even use the protected-clocks property and then parse it to
figure out to not register this gate?

> +       } else {
> +               gate =3D kzalloc(sizeof(*gate), GFP_KERNEL);
> +               if (!gate)
> +                       goto fail;
> +
> +               gate_hw =3D &gate->hw;
> +               gate->reg =3D reg;
> +               gate->bit_idx =3D PCG_CGC_SHIFT;
> +               gate->lock =3D &imx_ccm_lock;
> +       }