linux-kernel - Re: [PATCH] clk: allow to skip clk_core_req_round_rate

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Message-ID: <a25ff51d-d328-43d8-98af-91598c1ef23d@salutedevices.com>
Date: Tue, 20 Feb 2024 20:34:52 +0300
From: Jan Dakinevich <jan.dakinevich@...utedevices.com>
To: Michael Turquette <mturquette@...libre.com>, Stephen Boyd
	<sboyd@...nel.org>, <linux-clk@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
CC: <kernel@...utedevices.com>
Subject: Re: [PATCH] clk: allow to skip clk_core_req_round_rate_nolock()

Please take a look at this patch.

On 1/26/24 23:14, Jan Dakinevich wrote:
> Calling of clk_core_req_round_rate_nolock() can be time-consuming in a
> case of deep hierarchy with multiple dividers/parents. But if the clock
> already has exactly the same rate as desired, there is no need to
> determine how it could be rounded.
> 
> Signed-off-by: Jan Dakinevich <jan.dakinevich@...utedevices.com>
> ---
>   drivers/clk/clk.c | 6 ++++++
>   1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index 2253c154a824..04f0ddced932 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -2423,6 +2423,12 @@ static int clk_core_set_rate_nolock(struct clk_core *core,
>   	if (!core)
>   		return 0;
>   
> +	/* skip calculation of rounded rate if the clock already has exactly
> +	 * the same rate as desired
> +	 */
> +	if (req_rate == clk_core_get_rate_nolock(core))
> +		return 0;
> +
>   	rate = clk_core_req_round_rate_nolock(core, req_rate);
>   
>   	/* bail early if nothing to do */

-- 
Best regards
Jan Dakinevich