linux-kernel - Re: [PATCH 03/27] rtc: ac100: convert from divider_round_rate() to divider_determine

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Message-ID: <202601220026092a75a45e@mail.local>
Date: Thu, 22 Jan 2026 01:26:09 +0100
From: Alexandre Belloni <alexandre.belloni@...tlin.com>
To: Brian Masney <bmasney@...hat.com>
Cc: Michael Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...nel.org>, linux-clk@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-rtc@...r.kernel.org
Subject: Re: [PATCH 03/27] rtc: ac100: convert from divider_round_rate() to
 divider_determine_rate()

Hello,

On 08/01/2026 16:16:21-0500, Brian Masney wrote:
> The divider_round_rate() function is now deprecated, so let's migrate
> to divider_determine_rate() instead so that this deprecated API can be
> removed.
> 
> Signed-off-by: Brian Masney <bmasney@...hat.com>
> 
> ---
> To: Alexandre Belloni <alexandre.belloni@...tlin.com>
> Cc: linux-rtc@...r.kernel.org
> ---
>  drivers/rtc/rtc-ac100.c | 75 +++++++++++++++++++++++++------------------------
>  1 file changed, 38 insertions(+), 37 deletions(-)
> 
> diff --git a/drivers/rtc/rtc-ac100.c b/drivers/rtc/rtc-ac100.c
> index 33626311fa781b5ce90dcc472f948dc933bbc897..16aca4431da8c029e6195d8a3c9fe75fa95d0bc0 100644
> --- a/drivers/rtc/rtc-ac100.c
> +++ b/drivers/rtc/rtc-ac100.c
> @@ -140,42 +140,16 @@ static unsigned long ac100_clkout_recalc_rate(struct clk_hw *hw,
>  				   AC100_CLKOUT_DIV_WIDTH);
>  }
>  
> -static long ac100_clkout_round_rate(struct clk_hw *hw, unsigned long rate,
> -				    unsigned long prate)
> -{
> -	unsigned long best_rate = 0, tmp_rate, tmp_prate;
> -	int i;
> -
> -	if (prate == AC100_RTC_32K_RATE)
> -		return divider_round_rate(hw, rate, &prate, NULL,
> -					  AC100_CLKOUT_DIV_WIDTH,
> -					  CLK_DIVIDER_POWER_OF_TWO);
> -
> -	for (i = 0; ac100_clkout_prediv[i].div; i++) {
> -		tmp_prate = DIV_ROUND_UP(prate, ac100_clkout_prediv[i].val);
> -		tmp_rate = divider_round_rate(hw, rate, &tmp_prate, NULL,
> -					      AC100_CLKOUT_DIV_WIDTH,
> -					      CLK_DIVIDER_POWER_OF_TWO);
> -
> -		if (tmp_rate > rate)
> -			continue;
> -		if (rate - tmp_rate < best_rate - tmp_rate)
> -			best_rate = tmp_rate;
> -	}
> -
> -	return best_rate;
> -}
> -
>  static int ac100_clkout_determine_rate(struct clk_hw *hw,
>  				       struct clk_rate_request *req)
>  {
> -	struct clk_hw *best_parent;
> +	int i, ret, num_parents = clk_hw_get_num_parents(hw);
> +	struct clk_hw *best_parent = NULL;
>  	unsigned long best = 0;
> -	int i, num_parents = clk_hw_get_num_parents(hw);
>  
>  	for (i = 0; i < num_parents; i++) {
>  		struct clk_hw *parent = clk_hw_get_parent_by_index(hw, i);
> -		unsigned long tmp, prate;
> +		unsigned long prate;
>  
>  		/*
>  		 * The clock has two parents, one is a fixed clock which is
> @@ -199,13 +173,40 @@ static int ac100_clkout_determine_rate(struct clk_hw *hw,
>  
>  		prate = clk_hw_get_rate(parent);
>  
> -		tmp = ac100_clkout_round_rate(hw, req->rate, prate);
> -
> -		if (tmp > req->rate)
> -			continue;
> -		if (req->rate - tmp < req->rate - best) {
> -			best = tmp;
> -			best_parent = parent;
> +		if (prate == AC100_RTC_32K_RATE) {
> +			struct clk_rate_request div_req = *req;
> +
> +			div_req.best_parent_rate = prate;
> +
> +			ret = divider_determine_rate(hw, &div_req, NULL,
> +						     AC100_CLKOUT_DIV_WIDTH,
> +						     CLK_DIVIDER_POWER_OF_TWO);
> +			if (ret != 0 || div_req.rate > req->rate)
> +				continue;

This leaves a braces inbalance

> +			else if (req->rate - div_req.rate < req->rate - best) {
> +				best = div_req.rate;
> +				best_parent = parent;
> +			}
> +		} else {
> +			int j;
> +
> +			for (j = 0; ac100_clkout_prediv[j].div; j++) {
> +				struct clk_rate_request div_req = *req;
> +				unsigned long tmp_prate;
> +
> +				tmp_prate = DIV_ROUND_UP(prate, ac100_clkout_prediv[j].div);
> +				div_req.best_parent_rate = tmp_prate;
> +
> +				ret = divider_determine_rate(hw, &div_req, NULL,
> +							     AC100_CLKOUT_DIV_WIDTH,
> +							     CLK_DIVIDER_POWER_OF_TWO);
> +				if (ret != 0 || div_req.rate > req->rate)
> +					continue;

Ditto.

> +				else if (req->rate - div_req.rate < req->rate - best) {
> +					best = div_req.rate;
> +					best_parent = parent;
> +				}
> +			}
>  		}
>  	}


-- 
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com