On 08/28/2014 02:33 AM, Kuninori Morimoto wrote:

Hi Lars

Thank you for your comment

...

...

sound { compatible = "simple-audio-card";

/* FrontEnd */
simple-audio-card,dai-link@0 {
	...
	format = "left_j";
	remote = <&endpoint>;

	cpu {
		sound-dai = <&rcar_sound 0>;
	};
	codec { /* dummy */ };
};

/* BackEnd */
endpoint: simple-audio-card,dai-link@1 {
	...
	format = "left_j";

	cpu { /* dummy */ };
	codec1: codec {
		sound-dai = <&ak4643>;
	};
};

};

When you try to come up with with a binding try to completely ignore that something call DPCM exists. The binding is supposed to describe the hardware and how the different hardware components are interconnected. So try to come up with a binding that accurately describes the hardware connections. Once that is done try to map the binding onto the existing software framework. The last step may require some adjustments to the framework.

Now, my system is working well with simple-card by this

sound { compatible = "simple-audio-card"; ...

cpu {
	sound-dai = <&rcar_sound 0>;
};
codec {
	sound-dai = <&ak4643>;
};

};

The reason why I'm tring to support DPCM on simple-card is "sampling rate convert". My rcar_sound can convert sampling rate, and I tried to add this feature as rcar_sound property. But, Mark rejected and requests me to use DPCM for it, since it can be common featrue. Current existing simple-card can't use it, and I'm tring. But, am I misunderstanding ?

Is the sample rate converter a extra module, or is the sample rate converter just a feature of the I2S core?

- Lars

On Wed, Aug 27, 2014 at 05:33:55PM -0700, Kuninori Morimoto wrote:

Now, my system is working well with simple-card by this

sound { compatible = "simple-audio-card"; ...

cpu {
	sound-dai = <&rcar_sound 0>;
};
codec {
	sound-dai = <&ak4643>;
};

};

The reason why I'm tring to support DPCM on simple-card is "sampling rate convert". My rcar_sound can convert sampling rate, and I tried to add this feature as rcar_sound property. But, Mark rejected and requests me to use DPCM for it, since it can be common featrue. Current existing simple-card can't use it, and I'm tring. But, am I misunderstanding ?

There's two separate things here. One is how the code is implemented (which does look very much like it should be doing DPCM) and the other is how the DT binding looks - the DT binding is supposed to be a hardware neutral thing and not depend on Linux implementation details. If you've already got the hardware described well enough to discover everything then that generally indicates that the DT binding should not need to change.