linux-kernel - Re: [PATCH 1/4] clk: imx8mn: A53 core clock no need to be critical

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Message-ID: <65500dc7-dc03-7dc1-92cd-5557cd73232e@nxp.com>
Date:   Tue, 25 Feb 2020 08:58:22 +0000
From:   Daniel Baluta <daniel.baluta@....com>
To:     Anson Huang <anson.huang@....com>,
        "mturquette@...libre.com" <mturquette@...libre.com>,
        "sboyd@...nel.org" <sboyd@...nel.org>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>,
        "s.hauer@...gutronix.de" <s.hauer@...gutronix.de>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        "festevam@...il.com" <festevam@...il.com>,
        Leonard Crestez <leonard.crestez@....com>,
        Abel Vesa <abel.vesa@....com>, Peng Fan <peng.fan@....com>,
        Jacky Bai <ping.bai@....com>, Andy Duan <fugang.duan@....com>,
        "linux-clk@...r.kernel.org" <linux-clk@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     dl-linux-imx <linux-imx@....com>
Subject: Re: [PATCH 1/4] clk: imx8mn: A53 core clock no need to be critical

Hi Anson,

One comment inline:

On 25.02.2020 10:49, Anson Huang wrote:
> 'A53_CORE' is just a mux and no need to be critical, being critical
> will cause its parent clock always ON which does NOT make sense,
> to make sure CPU's hardware clock source NOT being disabled during
> clock tree setup, need to move the 'A53_SRC'/'A53_CORE' reparent
> operations to after critical clock 'ARM_CLK' setup finished.
>
> Signed-off-by: Anson Huang <Anson.Huang@....com>
> ---
>   drivers/clk/imx/clk-imx8mn.c | 8 ++++----
>   1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/clk/imx/clk-imx8mn.c b/drivers/clk/imx/clk-imx8mn.c
> index 83618af..0bc7070 100644
> --- a/drivers/clk/imx/clk-imx8mn.c
> +++ b/drivers/clk/imx/clk-imx8mn.c
> @@ -428,7 +428,7 @@ static int imx8mn_clocks_probe(struct platform_device *pdev)
>   	hws[IMX8MN_CLK_GPU_SHADER_DIV] = hws[IMX8MN_CLK_GPU_SHADER];
>   
>   	/* CORE SEL */
> -	hws[IMX8MN_CLK_A53_CORE] = imx_clk_hw_mux2_flags("arm_a53_core", base + 0x9880, 24, 1, imx8mn_a53_core_sels, ARRAY_SIZE(imx8mn_a53_core_sels), CLK_IS_CRITICAL);
> +	hws[IMX8MN_CLK_A53_CORE] = imx_clk_hw_mux2("arm_a53_core", base + 0x9880, 24, 1, imx8mn_a53_core_sels, ARRAY_SIZE(imx8mn_a53_core_sels));
>   
>   	/* BUS */
>   	hws[IMX8MN_CLK_MAIN_AXI] = imx8m_clk_hw_composite_critical("main_axi", imx8mn_main_axi_sels, base + 0x8800);
> @@ -559,15 +559,15 @@ static int imx8mn_clocks_probe(struct platform_device *pdev)
>   
>   	hws[IMX8MN_CLK_DRAM_ALT_ROOT] = imx_clk_hw_fixed_factor("dram_alt_root", "dram_alt", 1, 4);
>   
> -	clk_hw_set_parent(hws[IMX8MN_CLK_A53_SRC], hws[IMX8MN_SYS_PLL1_800M]);
> -	clk_hw_set_parent(hws[IMX8MN_CLK_A53_CORE], hws[IMX8MN_ARM_PLL_OUT]);


Why do you need to move this code? If there is a reason please add a 
separate patch and explain why.

> -
>   	hws[IMX8MN_CLK_ARM] = imx_clk_hw_cpu("arm", "arm_a53_core",
>   					   hws[IMX8MN_CLK_A53_CORE]->clk,
>   					   hws[IMX8MN_CLK_A53_CORE]->clk,
>   					   hws[IMX8MN_ARM_PLL_OUT]->clk,
>   					   hws[IMX8MN_CLK_A53_DIV]->clk);
>   
> +	clk_hw_set_parent(hws[IMX8MN_CLK_A53_SRC], hws[IMX8MN_SYS_PLL1_800M]);
> +	clk_hw_set_parent(hws[IMX8MN_CLK_A53_CORE], hws[IMX8MN_ARM_PLL_OUT]);
> +
>   	imx_check_clk_hws(hws, IMX8MN_CLK_END);
>   
>   	ret = of_clk_add_hw_provider(np, of_clk_hw_onecell_get, clk_hw_data);