linux-kernel - Re: [PATCH V2 2/2] clk: imx8m: check mcore

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Date:   Thu, 17 Mar 2022 12:38:13 -0700
From:   Stephen Boyd <sboyd@...nel.org>
To:     Peng Fan (OSS) <peng.fan@....nxp.com>, abel.vesa@....com,
        s.hauer@...gutronix.de, shawnguo@...nel.org
Cc:     kernel@...gutronix.de, festevam@...il.com, linux-imx@....com,
        linux-clk@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, Peng Fan <peng.fan@....com>
Subject: Re: [PATCH V2 2/2] clk: imx8m: check mcore_booted before register clk

Quoting Peng Fan (OSS) (2022-02-28 04:41:12)
> From: Peng Fan <peng.fan@....com>
> 
> 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.
> 
> Signed-off-by: Peng Fan <peng.fan@....com>
> ---
> 
> V2:
>  None
> 
>  drivers/clk/imx/clk-composite-8m.c | 21 +++++++++++++--------
>  1 file changed, 13 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/clk/imx/clk-composite-8m.c b/drivers/clk/imx/clk-composite-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 = &imx_ccm_lock;
>         div->flags = CLK_DIVIDER_ROUND_CLOSEST;
>  
> -       gate = kzalloc(sizeof(*gate), GFP_KERNEL);
> -       if (!gate)
> -               goto fail;
> -
> -       gate_hw = &gate->hw;
> -       gate->reg = reg;
> -       gate->bit_idx = PCG_CGC_SHIFT;
> -       gate->lock = &imx_ccm_lock;
> +       /* skip registering the gate ops if M4 is enabled */
> +       if (mcore_booted) {
> +               gate_hw = NULL;

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

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