linux-kernel - Re: [PATCH v4 5/9] clk: at91: clk-generated: create function to find best

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Message-ID: <f384980c-6a01-6879-e60c-d261fb4ae388@microchip.com>
Date:   Tue, 25 Jul 2017 17:33:50 +0200
From:   Nicolas Ferre <nicolas.ferre@...rochip.com>
To:     Quentin Schulz <quentin.schulz@...e-electrons.com>,
        <mturquette@...libre.com>, <sboyd@...eaurora.org>,
        <robh+dt@...nel.org>, <mark.rutland@....com>,
        <lgirdwood@...il.com>, <broonie@...nel.org>,
        <alexandre.belloni@...e-electrons.com>, <linux@...linux.org.uk>,
        <boris.brezillon@...e-electrons.com>, <perex@...ex.cz>,
        <tiwai@...e.com>
CC:     <cyrille.pitchen@...ev4u.fr>,
        <thomas.petazzoni@...e-electrons.com>, <linux-clk@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <alsa-devel@...a-project.org>,
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v4 5/9] clk: at91: clk-generated: create function to find
 best_diff

On 25/07/2017 at 09:37, Quentin Schulz wrote:
> The way to find the best_diff and do the appropriate process afterwards
> can be re-used.
> 
> This patch prepares the driver for an upcoming patch that will allow
> clk_generated to determine the rate of the audio_pll.
> 
> Signed-off-by: Quentin Schulz <quentin.schulz@...e-electrons.com>
> Acked-by: Boris Brezillon <boris.brezillon@...e-electrons.com>

Acked-by: Nicolas Ferre <nicolas.ferre@...rochip.com>

> ---
>  drivers/clk/at91/clk-generated.c | 41 +++++++++++++++++++++------------
>  1 file changed, 27 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/clk/at91/clk-generated.c b/drivers/clk/at91/clk-generated.c
> index ef4b4e0..7260e49 100644
> --- a/drivers/clk/at91/clk-generated.c
> +++ b/drivers/clk/at91/clk-generated.c
> @@ -99,15 +99,36 @@ clk_generated_recalc_rate(struct clk_hw *hw,
>  	return DIV_ROUND_CLOSEST(parent_rate, gck->gckdiv + 1);
>  }
>  
> +static void clk_generated_best_diff(struct clk_rate_request *req,
> +				    struct clk_hw *parent,
> +				    unsigned long parent_rate, u32 div,
> +				    int *best_diff, long *best_rate)
> +{
> +	unsigned long tmp_rate;
> +	int tmp_diff;
> +
> +	if (!div)
> +		tmp_rate = parent_rate;
> +	else
> +		tmp_rate = parent_rate / div;
> +	tmp_diff = abs(req->rate - tmp_rate);
> +
> +	if (*best_diff < 0 || *best_diff > tmp_diff) {
> +		*best_rate = tmp_rate;
> +		*best_diff = tmp_diff;
> +		req->best_parent_rate = parent_rate;
> +		req->best_parent_hw = parent;
> +	}
> +}
> +
>  static int clk_generated_determine_rate(struct clk_hw *hw,
>  					struct clk_rate_request *req)
>  {
>  	struct clk_generated *gck = to_clk_generated(hw);
>  	struct clk_hw *parent = NULL;
>  	long best_rate = -EINVAL;
> -	unsigned long tmp_rate, min_rate;
> +	unsigned long min_rate;
>  	int best_diff = -1;
> -	int tmp_diff;
>  	int i;
>  
>  	for (i = 0; i < clk_hw_get_num_parents(hw); i++) {
> @@ -125,18 +146,10 @@ static int clk_generated_determine_rate(struct clk_hw *hw,
>  			continue;
>  
>  		div = DIV_ROUND_CLOSEST(parent_rate, req->rate);
> -		if (!div)
> -			tmp_rate = parent_rate;
> -		else
> -			tmp_rate = parent_rate / div;
> -		tmp_diff = abs(req->rate - tmp_rate);
> -
> -		if (best_diff < 0 || best_diff > tmp_diff) {
> -			best_rate = tmp_rate;
> -			best_diff = tmp_diff;
> -			req->best_parent_rate = parent_rate;
> -			req->best_parent_hw = parent;
> -		}
> +
> +		clk_generated_best_diff(req, parent, parent_rate, div,
> +					&best_diff, &best_rate);
> +
>  
>  		if (!best_diff)
>  			break;
> 


-- 
Nicolas Ferre