linux-kernel - Re: [PATCH 2/2] clk: divider: fix to set parent rate from CLK_DIVIDER_READ

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Message-ID: <20150604224238.GB8099@codeaurora.org>
Date:	Thu, 4 Jun 2015 15:42:38 -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 2/2] clk: divider: fix to set parent rate from
 CLK_DIVIDER_READ_ONLY flag

On 04/07, Joonyoung Shim wrote:
> The round_rate callback function will returns alway same parent clk rate
> of divider with CLK_DIVIDER_READ_ONLY flag. If be used
> CLK_SET_RATE_PARENT flag with CLK_DIVIDER_READ_ONLY flag, then never
> change parent clk rate anymore.
> 
> From this case, this patch allows to change parent clk rate.
> 
> Signed-off-by: Joonyoung Shim <jy0922.shim@...sung.com>
> ---
>  drivers/clk/clk-divider.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/clk/clk-divider.c b/drivers/clk/clk-divider.c
> index ce34d29a..37e285e 100644
> --- a/drivers/clk/clk-divider.c
> +++ b/drivers/clk/clk-divider.c
> @@ -352,6 +352,11 @@ static long clk_divider_round_rate(struct clk_hw *hw, unsigned long rate,
>  		bestdiv = readl(divider->reg) >> divider->shift;
>  		bestdiv &= div_mask(divider->width);
>  		bestdiv = _get_div(divider->table, bestdiv, divider->flags);
> +
> +		if ((__clk_get_flags(hw->clk) & CLK_SET_RATE_PARENT))
> +			*prate = __clk_round_rate(__clk_get_parent(hw->clk),
> +						  rate);
> +
>  		return DIV_ROUND_UP(*prate, bestdiv);

Doesn't this assume that the divider is 1? Otherwise we should be
multiplying the rate up by whatever the divider is that we have
in the hardware.

-- 
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