linux-kernel - Re: [PATCH] soc: imx8m: Enable OCOTP clock for imx8mm before reading registers

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Date:   Mon, 18 Sep 2023 12:20:31 +1000
From:   Nathan Rossi <nathan@...hanrossi.com>
To:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:     Nathan Rossi <nathan.rossi@...i.com>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>
Subject: Re: [PATCH] soc: imx8m: Enable OCOTP clock for imx8mm before reading registers

On Mon, 14 Aug 2023 at 11:57, Nathan Rossi <nathan@...hanrossi.com> wrote:
>
> From: Nathan Rossi <nathan.rossi@...i.com>
>
> Commit 836fb30949d9 ("soc: imx8m: Enable OCOTP clock before reading the
> register") added configuration to enable the OCOTP clock before
> attempting to read from the associated registers.
>
> This same kexec issue is present with the imx8m SoCs that use the
> imx8mm_soc_uid function (e.g. imx8mp). This requires the imx8mm_soc_uid
> function to configure the OCOTP clock before accessing the associated
> registers. This change implements the same clock enable functionality
> that is present in the imx8mq_soc_revision function for the
> imx8mm_soc_uid function.

Gentle ping. Are there any comments or feedback on this change?

Thanks,
Nathan

>
> Signed-off-by: Nathan Rossi <nathan.rossi@...i.com>
> ---
>  drivers/soc/imx/soc-imx8m.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
>
> diff --git a/drivers/soc/imx/soc-imx8m.c b/drivers/soc/imx/soc-imx8m.c
> index 1dcd243df5..ec87d9d878 100644
> --- a/drivers/soc/imx/soc-imx8m.c
> +++ b/drivers/soc/imx/soc-imx8m.c
> @@ -100,6 +100,7 @@ static void __init imx8mm_soc_uid(void)
>  {
>         void __iomem *ocotp_base;
>         struct device_node *np;
> +       struct clk *clk;
>         u32 offset = of_machine_is_compatible("fsl,imx8mp") ?
>                      IMX8MP_OCOTP_UID_OFFSET : 0;
>
> @@ -109,11 +110,20 @@ static void __init imx8mm_soc_uid(void)
>
>         ocotp_base = of_iomap(np, 0);
>         WARN_ON(!ocotp_base);
> +       clk = of_clk_get_by_name(np, NULL);
> +       if (IS_ERR(clk)) {
> +               WARN_ON(IS_ERR(clk));
> +               return;
> +       }
> +
> +       clk_prepare_enable(clk);
>
>         soc_uid = readl_relaxed(ocotp_base + OCOTP_UID_HIGH + offset);
>         soc_uid <<= 32;
>         soc_uid |= readl_relaxed(ocotp_base + OCOTP_UID_LOW + offset);
>
> +       clk_disable_unprepare(clk);
> +       clk_put(clk);
>         iounmap(ocotp_base);
>         of_node_put(np);
>  }
> ---
> 2.40.1