linux-kernel - Re: [PATCH RFC v2 3/4] clk: keystone: sci-clk: add restore

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Message-ID: <1283df52-ee41-477f-8d91-5c4a02385cef@ti.com>
Date: Wed, 3 Dec 2025 13:20:24 +0530
From: "Kumar, Udit" <u-kumar1@...com>
To: "Thomas Richard (TI.com)" <thomas.richard@...tlin.com>, Nishanth Menon
	<nm@...com>, Tero Kristo <kristo@...nel.org>, Santosh Shilimkar
	<ssantosh@...nel.org>, Michael Turquette <mturquette@...libre.com>, "Stephen
 Boyd" <sboyd@...nel.org>
CC: Gregory CLEMENT <gregory.clement@...tlin.com>,
	<richard.genoud@...tlin.com>, Prasanth Mantena <p-mantena@...com>, "Abhash
 Kumar" <a-kumar2@...com>, Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
	<linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
	<linux-clk@...r.kernel.org>, <u-kumar1@...com>
Subject: Re: [PATCH RFC v2 3/4] clk: keystone: sci-clk: add restore_context()
 operation


On 11/27/2025 2:08 PM, Thomas Richard (TI.com) wrote:
> Implement the restore_context() operation to restore the clock parent
> state. The parent index is saved in sci_clk struct during set_parent().
> During clock registration, the core retrieves each clock’s parent using
> get_parent() operation to ensure the internal clock tree reflects the
> actual hardware state, including any configurations made by the
> bootloader. So we also save the parent index in get_parent().
>
> Signed-off-by: Thomas Richard (TI.com) <thomas.richard@...tlin.com>
> ---
>   drivers/clk/keystone/sci-clk.c | 25 ++++++++++++++++++++-----
>   1 file changed, 20 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/clk/keystone/sci-clk.c b/drivers/clk/keystone/sci-clk.c
> index a4b42811de55d..1e5dd01484d1c 100644
> --- a/drivers/clk/keystone/sci-clk.c
> +++ b/drivers/clk/keystone/sci-clk.c
> @@ -47,6 +47,7 @@ struct sci_clk_provider {
>    * @node:	 Link for handling clocks probed via DT
>    * @cached_req:	 Cached requested freq for determine rate calls
>    * @cached_res:	 Cached result freq for determine rate calls
> + * @parent_id:	 Parent index for this clock
>    */
>   struct sci_clk {
>   	struct clk_hw hw;
> @@ -58,6 +59,7 @@ struct sci_clk {
>   	struct list_head node;
>   	unsigned long cached_req;
>   	unsigned long cached_res;
> +	u8 parent_id;

you may need to restore rate as well


>   };
>   
>   #define to_sci_clk(_hw) container_of(_hw, struct sci_clk, hw)
> @@ -237,9 +239,9 @@ static u8 sci_clk_get_parent(struct clk_hw *hw)
>   		return 0;
>   	}
>   
> -	parent_id = parent_id - clk->clk_id - 1;
> +	clk->parent_id = (u8)(parent_id - clk->clk_id - 1);
>   
> -	return (u8)parent_id;
> +	return clk->parent_id;
>   }
>   
>   /**
> @@ -252,12 +254,24 @@ static u8 sci_clk_get_parent(struct clk_hw *hw)
>   static int sci_clk_set_parent(struct clk_hw *hw, u8 index)
>   {
>   	struct sci_clk *clk = to_sci_clk(hw);
> +	int ret;
>   
>   	clk->cached_req = 0;
>   
> -	return clk->provider->ops->set_parent(clk->provider->sci, clk->dev_id,
> -					      clk->clk_id,
> -					      index + 1 + clk->clk_id);
> +	ret = clk->provider->ops->set_parent(clk->provider->sci, clk->dev_id,
> +					     clk->clk_id,
> +					     index + 1 + clk->clk_id);
> +	if (!ret)
> +		clk->parent_id = index;
> +
> +	return ret;
> +}
> +
> +static void sci_clk_restore_context(struct clk_hw *hw)
> +{
> +	struct sci_clk *clk = to_sci_clk(hw);
> +
> +	sci_clk_set_parent(hw, clk->parent_id);

You should restore,  if this is BOARD_CFG managed


>   }
>   
>   static const struct clk_ops sci_clk_ops = {
> @@ -269,6 +283,7 @@ static const struct clk_ops sci_clk_ops = {
>   	.set_rate = sci_clk_set_rate,
>   	.get_parent = sci_clk_get_parent,
>   	.set_parent = sci_clk_set_parent,
> +	.restore_context = sci_clk_restore_context,
>   };
>   
>   /**
>