linux-kernel - Re: [PATCH] clk: fractional-divider: check parent rate only for general approximation

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Message-ID: <063dea80-a13e-3af2-1008-1c0c2bbe2706@katsuster.net>
Date:   Sat, 26 Jan 2019 20:13:48 +0900
From:   Katsuhiro Suzuki <katsuhiro@...suster.net>
To:     Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>, linux-clk@...r.kernel.org
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] clk: fractional-divider: check parent rate only for
 general approximation

Ping...

On 2019/01/07 22:21, Katsuhiro Suzuki wrote:
> Custom approximation of fractional-divider may not need parent clock
> rate checking. For example Rockchip SoCs work fine using grand parent
> clock rate evne if target rate is greater than parent.
> 
> This patch removes parent clock rate check from custom approximation.
> 
> Signed-off-by: Katsuhiro Suzuki <katsuhiro@...suster.net>
> ---
>   drivers/clk/clk-fractional-divider.c | 10 +++++++---
>   1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/clk/clk-fractional-divider.c b/drivers/clk/clk-fractional-divider.c
> index 545dceec0bbf..b0fc5509e0ff 100644
> --- a/drivers/clk/clk-fractional-divider.c
> +++ b/drivers/clk/clk-fractional-divider.c
> @@ -79,13 +79,17 @@ static long clk_fd_round_rate(struct clk_hw *hw, unsigned long rate,
>   	unsigned long m, n;
>   	u64 ret;
>   
> -	if (!rate || rate >= *parent_rate)
> +	if (!rate)
>   		return *parent_rate;
>   
> -	if (fd->approximation)
> +	if (fd->approximation) {
>   		fd->approximation(hw, rate, parent_rate, &m, &n);
> -	else
> +	} else {
> +		if (rate >= *parent_rate)
> +			return *parent_rate;
> +
>   		clk_fd_general_approximation(hw, rate, parent_rate, &m, &n);
> +	}
>   
>   	ret = (u64)*parent_rate * m;
>   	do_div(ret, n);
>