linux-kernel - Re: [PATCH v3 3/4] clk: keystone: sci-clk: add restore

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Message-ID: <a12c3825-a80e-491f-a862-9cd5151a5f73@ti.com>
Date: Tue, 16 Dec 2025 08:25:28 +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>
Subject: Re: [PATCH v3 3/4] clk: keystone: sci-clk: add restore_context()
 operation


On 12/5/2025 7:58 PM, Thomas Richard (TI.com) wrote:
> Implement the restore_context() operation to restore the clock rate and the
> clock parent state. The clock rate is saved in sci_clk struct during
> set_rate() operation. The parent index is saved in sci_clk struct during
> set_parent() operation. 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 | 42 ++++++++++++++++++++++++++++++++++--------
>   1 file changed, 34 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/clk/keystone/sci-clk.c b/drivers/clk/keystone/sci-clk.c
> index 9d5071223f4cb..428050a05de31 100644
> --- a/drivers/clk/keystone/sci-clk.c
> +++ b/drivers/clk/keystone/sci-clk.c
> @@ -47,6 +47,8 @@ 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
> + * @rate:	 Clock rate
>    */
>   struct sci_clk {
>   	struct clk_hw hw;
> @@ -58,6 +60,8 @@ struct sci_clk {
>   	struct list_head node;
>   	unsigned long cached_req;
>   	unsigned long cached_res;
> +	u8 parent_id;
> +	unsigned long rate;
>   };
>   
>   #define to_sci_clk(_hw) container_of(_hw, struct sci_clk, hw)
> @@ -210,10 +214,16 @@ static int sci_clk_set_rate(struct clk_hw *hw, unsigned long rate,
>   			    unsigned long parent_rate)
>   {
>   	struct sci_clk *clk = to_sci_clk(hw);
> +	int ret;
> +
> +	ret = clk->provider->ops->set_freq(clk->provider->sci, clk->dev_id,
> +					   clk->clk_id, rate / 10 * 9, rate,
> +					   rate / 10 * 11);
>   
> -	return clk->provider->ops->set_freq(clk->provider->sci, clk->dev_id,
> -					    clk->clk_id, rate / 10 * 9, rate,
> -					    rate / 10 * 11);
> +	if (!ret)
> +		clk->rate = rate;
> +
> +	return ret;
>   }
>   
>   /**
> @@ -237,9 +247,9 @@ 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 +262,27 @@ 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);
> +
> +	if (clk->rate)
> +		sci_clk_set_rate(hw, clk->rate, 0);


Mostly looks ok ,  Please add some warning prints in case of resume path 
either of

sci_clk_set_parent/sci_clk_set_rate returned failure


>   }
>   
>   static const struct clk_ops sci_clk_ops = {
> @@ -269,6 +294,7 @@ 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,
>   };
>   
>   /**
>