linux-kernel - Re: [PATCH 1/2] clk: divider: don't set_rate with CLK_DIVIDER_READ

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Date:	Thu, 4 Jun 2015 15:44:07 -0700
From:	Stephen Boyd <sboyd@...eaurora.org>
To:	Joonyoung Shim <jy0922.shim@...sung.com>
Cc:	linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org,
	mturquette@...aro.org, haojian.zhuang@...il.com,
	james.hogan@...tec.com
Subject: Re: [PATCH 1/2] clk: divider: don't set_rate with
 CLK_DIVIDER_READ_ONLY flag

On 04/07, Joonyoung Shim wrote:
> Even if use CLK_DIVIDER_READ_ONLY flag, divider setting can be changed
> by set_rate callback. Don't change divider setting from set_rate
> callback of divider with CLK_DIVIDER_READ_ONLY flag.
> 
> Signed-off-by: Joonyoung Shim <jy0922.shim@...sung.com>
> ---
>  drivers/clk/clk-divider.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/clk/clk-divider.c b/drivers/clk/clk-divider.c
> index 25006a8..ce34d29a 100644
> --- a/drivers/clk/clk-divider.c
> +++ b/drivers/clk/clk-divider.c
> @@ -384,6 +384,9 @@ static int clk_divider_set_rate(struct clk_hw *hw, unsigned long rate,
>  	unsigned long flags = 0;
>  	u32 val;
>  
> +	if (divider->flags & CLK_DIVIDER_READ_ONLY)
> +		return 0;
> +
>  	value = divider_get_val(rate, parent_rate, divider->table,
>  				divider->width, divider->flags);
>  

I wonder if it would make more sense to have different ops for
read only dividers. We would need to have an empty clk_set_rate
op in the case where the CCF tries to set the rate to what it
already is and then the proper recalc_rate and round_rate ops for
read only devices. At the least, this patch looks correct.

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