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

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Message-ID: <20260122020207de2216d9@mail.local>
Date: Thu, 22 Jan 2026 03:02:07 +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()

On 21/01/2026 19:48:19-0500, Brian Masney wrote:
> Hi Alexandre,
> 
> On Thu, Jan 22, 2026 at 01:26:09AM +0100, Alexandre Belloni wrote:
> > 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
> 
> To be clear, you also want the braces around the if like this:
> 
> if (ret != 0 || div_req.rate > req->rate) {
> 	continue;
> } else if (req->rate - div_req.rate < req->rate - best) {
> 	best = div_req.rate;
> 	best_parent = parent;
> }
> 

Yes, you can change that and add my ack on v2, I'm fine with this going
through clk.


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