linux-kernel - Re: [PATCH] sound: soc: fsl: Do not set DAI sysclk when it is equal to system freq

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Date:   Wed, 6 Sep 2017 23:18:54 +0200
From:   Łukasz Majewski <lukma@...x.de>
To:     Nicolin Chen <nicoleotsuka@...il.com>
Cc:     Fabio Estevam <fabio.estevam@....com>, Timur Tabi <timur@...i.org>,
        Xiubo Li <Xiubo.Lee@...il.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>,
        "festevam@...il.com" <festevam@...il.com>,
        "alsa-devel@...a-project.org" <alsa-devel@...a-project.org>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] sound: soc: fsl: Do not set DAI sysclk when it is equal
 to system freq

On 09/06/2017 09:47 PM, Nicolin Chen wrote:
> On Wed, Sep 06, 2017 at 08:35:50PM +0200, Łukasz Majewski wrote:
>   
>> 	clocks = <&clks IMX6QDL_CLK_SSI2_IPG>,
>> 		 <&clks IMX6QDL_CLK_SSI2>;
>> 	clock-names = "ipg", "baud";
> 
>>>>   			dailink_master: cpu {
>>>>   			    sound-dai = <&ssi2>;
>>>> 			    clock = <&SSSS>;
>>
>> 	If possible I do prefer a solution, which uses only DTS.
>> Side question - how to refer to baud clock from [1]?
> 
> Just add a property to this cpu node like:
> 	clock = <&clks IMX6QDL_CLK_SSI2>;

Ok.

> 
>>>> 			    system-clock-frequency = <XXXX>;
> 
> This would not be necessary unless you want to specify a clock rate
> so as to override the clock rate configuration in hw_params().

Ok.

> 
>>> This is the right solution based on current simple-card driver. For
>>> SSI (having two clocks), you have to specify the baud clock in the
>>> cpu node like that. I believe this is what the simple-card designer
>>> expected users to do since the cpu node is the first place that the
>>> driver tries to look at.
>>
>> I will give a shoot the option with adding the ipg clock.
> 
> No, not ipg clock. You should use the second clock -- baud clock.

Yes. Correct - the baud clock.

> 


-- 
Best regards,

Lukasz Majewski

--

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