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Date:   Tue, 12 Apr 2022 10:58:50 +0300
From:   Abel Vesa <abel.vesa@nxp.com>
To:     "Peng Fan (OSS)" <peng.fan@oss.nxp.com>
Cc:     sboyd@kernel.org, shawnguo@kernel.org, s.hauer@pengutronix.de,
        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>
Subject: Re: [PATCH V2 1/2] clk: imx: add mcore_booted module paratemter
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On 22-02-28 20:41:11, Peng Fan (OSS) wrote:
> From: Peng Fan <peng.fan@nxp.com>
>
> Add mcore_booted boot parameter which could simplify AMP clock
> management. To i.MX8M, there is CCM(clock control Module) to generate
> clock root clock, anatop(analog PLL module) to generate PLL, and CCGR
> (clock gating) to gate clocks to peripherals. As below:
>   anatop->ccm->ccgr->peripheral
>
> Linux handles the clock management and the auxiliary core is under
> control of Linux. Although there is per hardware domain control for CCGR
> and CCM, auxiliary core normally only use CCGR hardware domain control
> to avoid linux gate off the clk to peripherals and leave CCM ana anatop
> to Linux.
>
> Per NXP hardware design, because CCGR already support gate to
> peripherals, and clk root gate power leakage is negligible. So
> when in AMP case, we could not register the clk root gate.
>
> Signed-off-by: Peng Fan <peng.fan@nxp.com>

I agree with this approach since every other option complicates things
more.

Reviewed-by: Abel Vesa <abel.vesa@nxp.com>

> ---
>
> V2:
>  Switch to use module parameter, tested on i.MX8MP-EVK
>
>  drivers/clk/imx/clk-imx8mm.c | 2 ++
>  drivers/clk/imx/clk-imx8mn.c | 2 ++
>  drivers/clk/imx/clk-imx8mp.c | 2 ++
>  drivers/clk/imx/clk-imx8mq.c | 2 ++
>  drivers/clk/imx/clk.c        | 3 +++
>  drivers/clk/imx/clk.h        | 1 +
>  6 files changed, 12 insertions(+)
>
> diff --git a/drivers/clk/imx/clk-imx8mm.c b/drivers/clk/imx/clk-imx8mm.c
> index e8cbe181ec06..a452fd1bb891 100644
> --- a/drivers/clk/imx/clk-imx8mm.c
> +++ b/drivers/clk/imx/clk-imx8mm.c
> @@ -639,6 +639,8 @@ static struct platform_driver imx8mm_clk_driver = {
>  	},
>  };
>  module_platform_driver(imx8mm_clk_driver);
> +module_param(mcore_booted, bool, S_IRUGO);
> +MODULE_PARM_DESC(mcore_booted, "See Cortex-M core is booted or not");
>
>  MODULE_AUTHOR("Bai Ping <ping.bai@nxp.com>");
>  MODULE_DESCRIPTION("NXP i.MX8MM clock driver");
> diff --git a/drivers/clk/imx/clk-imx8mn.c b/drivers/clk/imx/clk-imx8mn.c
> index 92fcbab4f5be..dc69b7464b3d 100644
> --- a/drivers/clk/imx/clk-imx8mn.c
> +++ b/drivers/clk/imx/clk-imx8mn.c
> @@ -594,6 +594,8 @@ static struct platform_driver imx8mn_clk_driver = {
>  	},
>  };
>  module_platform_driver(imx8mn_clk_driver);
> +module_param(mcore_booted, bool, S_IRUGO);
> +MODULE_PARM_DESC(mcore_booted, "See Cortex-M core is booted or not");
>
>  MODULE_AUTHOR("Anson Huang <Anson.Huang@nxp.com>");
>  MODULE_DESCRIPTION("NXP i.MX8MN clock driver");
> diff --git a/drivers/clk/imx/clk-imx8mp.c b/drivers/clk/imx/clk-imx8mp.c
> index 18f5b7c3ca9d..250e45d9f844 100644
> --- a/drivers/clk/imx/clk-imx8mp.c
> +++ b/drivers/clk/imx/clk-imx8mp.c
> @@ -721,6 +721,8 @@ static struct platform_driver imx8mp_clk_driver = {
>  	},
>  };
>  module_platform_driver(imx8mp_clk_driver);
> +module_param(mcore_booted, bool, S_IRUGO);
> +MODULE_PARM_DESC(mcore_booted, "See Cortex-M core is booted or not");
>
>  MODULE_AUTHOR("Anson Huang <Anson.Huang@nxp.com>");
>  MODULE_DESCRIPTION("NXP i.MX8MP clock driver");
> diff --git a/drivers/clk/imx/clk-imx8mq.c b/drivers/clk/imx/clk-imx8mq.c
> index 83cc2b1c3294..33897b56130d 100644
> --- a/drivers/clk/imx/clk-imx8mq.c
> +++ b/drivers/clk/imx/clk-imx8mq.c
> @@ -632,6 +632,8 @@ static struct platform_driver imx8mq_clk_driver = {
>  	},
>  };
>  module_platform_driver(imx8mq_clk_driver);
> +module_param(mcore_booted, bool, S_IRUGO);
> +MODULE_PARM_DESC(mcore_booted, "See Cortex-M core is booted or not");
>
>  MODULE_AUTHOR("Abel Vesa <abel.vesa@nxp.com>");
>  MODULE_DESCRIPTION("NXP i.MX8MQ clock driver");
> diff --git a/drivers/clk/imx/clk.c b/drivers/clk/imx/clk.c
> index 7cc669934253..4bd6ad060eea 100644
> --- a/drivers/clk/imx/clk.c
> +++ b/drivers/clk/imx/clk.c
> @@ -17,6 +17,9 @@
>  DEFINE_SPINLOCK(imx_ccm_lock);
>  EXPORT_SYMBOL_GPL(imx_ccm_lock);
>
> +bool mcore_booted;
> +EXPORT_SYMBOL_GPL(mcore_booted);
> +
>  void imx_unregister_clocks(struct clk *clks[], unsigned int count)
>  {
>  	unsigned int i;
> diff --git a/drivers/clk/imx/clk.h b/drivers/clk/imx/clk.h
> index a7cbbcd1a3f4..5061a06468df 100644
> --- a/drivers/clk/imx/clk.h
> +++ b/drivers/clk/imx/clk.h
> @@ -7,6 +7,7 @@
>  #include <linux/clk-provider.h>
>
>  extern spinlock_t imx_ccm_lock;
> +extern bool mcore_booted;
>
>  void imx_check_clocks(struct clk *clks[], unsigned int count);
>  void imx_check_clk_hws(struct clk_hw *clks[], unsigned int count);
> --
> 2.25.1
>