linux-kernel - Re: [PATCH] clk: rockchip: rk3288: i2s_frac adds flag to set parent's rate

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Date:	Sat, 11 Oct 2014 20:54:56 +0200
From:	Heiko Stübner <heiko@...ech.de>
To:	Jianqun <jay.xu@...k-chips.com>
Cc:	mturquette@...aro.org, dianders@...omium.org,
	kever.yang@...k-chips.com, dbasehore@...omium.org,
	mark.yao@...k-chips.com, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org, huangtao@...k-chips.com,
	cf@...k-chips.com
Subject: Re: [PATCH] clk: rockchip: rk3288: i2s_frac adds flag to set parent's rate

Hi Jianqun,

Am Dienstag, 30. September 2014, 11:12:04 schrieb Jianqun:
> The relation of i2s nodes as follows:
>           i2s_src               0           0            594000000  0
>              i2s_frac           0           0            11289600   0
>                 i2s_pre         0           0            11289600   0
>                    sclk_i2s0    0           0            11289600   0
>                    i2s0_clkout  0           0            11289600   0
>                       hclk_i2s0 1           1            99000000   0
> 
> sclk_i2s0 is the master clock, when to set rate of sclk_i2s0, should
> allow to set its parent's rate, by add flag CLK_SET_RATE_PARENT for
> "i2s_frac", "i2s_pre", "i2s0_clkout" and "sclk_i2s0".
> 
> Tested on rk3288 board using max98090, with command "aplay <music.wav>"
> 
> Change-Id: I12faad082566532b65a7de8c0a6845e1c17870e6

Please no "Change-Id"s in upstream patches.


> Signed-off-by: Jianqun <jay.xu@...k-chips.com>
> ---
>  drivers/clk/rockchip/clk-rk3288.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/clk/rockchip/clk-rk3288.c
> b/drivers/clk/rockchip/clk-rk3288.c index c770de0..baf19b4 100644
> --- a/drivers/clk/rockchip/clk-rk3288.c
> +++ b/drivers/clk/rockchip/clk-rk3288.c
> @@ -301,15 +301,15 @@ static struct rockchip_clk_branch
> rk3288_clk_branches[] __initdata = { COMPOSITE(0, "i2s_src",
> mux_pll_src_cpll_gpll_p, 0,
>  			RK3288_CLKSEL_CON(4), 15, 1, MFLAGS, 0, 7, DFLAGS,
>  			RK3288_CLKGATE_CON(4), 1, GFLAGS),
> -	COMPOSITE_FRAC(0, "i2s_frac", "i2s_src", 0,
> +	COMPOSITE_FRAC(0, "i2s_frac", "i2s_src", CLK_SET_RATE_PARENT,
>  			RK3288_CLKSEL_CON(8), 0,
>  			RK3288_CLKGATE_CON(4), 2, GFLAGS),
> -	MUX(0, "i2s_pre", mux_i2s_pre_p, 0,
> +	MUX(0, "i2s_pre", mux_i2s_pre_p, CLK_SET_RATE_PARENT,
>  			RK3288_CLKSEL_CON(4), 8, 2, MFLAGS),
> -	COMPOSITE_NODIV(0, "i2s0_clkout", mux_i2s_clkout_p, 0,
> +	COMPOSITE_NODIV(0, "i2s0_clkout", mux_i2s_clkout_p, CLK_SET_RATE_PARENT,

are you sure it is correct that i2s0_clkout should also be able to set the 
core i2s clock?

I.e. as it is now, the i2s controller could set one frequency through 
sclk_i2s0 and whatever uses i2s0_clkout would be able to set it to something 
completely different, which may call for trouble.

So in my mind, it might be better to limit i2s0_clkout to select between its 
two parent without being able influence the core i2s clock?


Heiko


>  			RK3288_CLKSEL_CON(4), 12, 1, MFLAGS,
>  			RK3288_CLKGATE_CON(4), 0, GFLAGS),
> -	GATE(SCLK_I2S0, "sclk_i2s0", "i2s_pre", 0,
> +	GATE(SCLK_I2S0, "sclk_i2s0", "i2s_pre", CLK_SET_RATE_PARENT,
>  			RK3288_CLKGATE_CON(4), 3, GFLAGS),
> 
>  	MUX(0, "spdif_src", mux_pll_src_cpll_gpll_p, 0,

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