Hi Nicolin,
On Tue, Sep 05, 2017 at 10:35:34AM +0200, Łukasz Majewski wrote:
And apparently, we shouldn't set bitclk to 66MHz either. Can
you help to find where this 66MHz comes from?
2. int asoc_simple_card_init_dai() @ simple-card-utils.c
Oh, I just searched in the simple-card.c but missed this file.
In this function (point 2.) the
simple_dai->sysclk is set and:
snd_soc_dai_set_sysclk(dai, 0, simple_dai->sysclk, 0)
which sets frequency to 66 MHz [*].
The asoc_simple_card_init_dai() is called in
asoc_simple_card_dai_init() @ simple-card.c
which is assigned to dai_link->init
dai_link->init = asoc_simple_card_dai_init; @ simple_card.c
And the sysclk itself is defined at:
-------------------------------------
dai_props->codec_dai->sysclk, which is used at:a
Why codec_dai? Why not dai_props->cpu_dai->sysclk since we are talking
about SSI?
This is how the simple-card (simple-sound-card) is written.
asoc_simple_card_startup(), asoc_simple_card_shutdown() and others
functions at simple-card.c
It is setup at:
asoc_simple_card_parse_clk() @ simple-card-utils.c from macro:
#define asoc_simple_card_parse_clk_cpu()
And the problem is:
-------------------
At the
asoc_simple_card_parse_clk()
we finally go to dts node:
/soc/aips-bus@02100000/i2c@021a0000/tfa9879@6C
This tfa9879 should be the CODEC right?
Yes. The tfa9879 is a codec (very simple -> I2S + I2C, mono).
They key point here is the asoc_simple_card_parse_clk() function from
simple-card-utils.c
Please look how the clock is assigned; It first checks for cpu clock,
then for "system-clock-frequency" DTS node and _finally_ looks for
another "child" clock [1], which is the codec attached to I2C.
And from there it takes the 66 MHz CLK:
/soc/aips-bus@02100000/i2c@021a0000/tfa9879@6C
which has clock from I2C (66 MHz).
You mean I2C scl or I2S sclk?
I2C scl.
-----------------------------------------------------------------
But anyway, I feel very confused here as you have 66MHz clock rate
(regardless of it purpose) for a codec dai but it's been passed to
a cpu dai (SSI).
Please look into asoc_simple_card_parse_clk().
My DTS [1] (it is different than other in-tree supported codecs - at
least I did not find similar setup in DTSes):
sound {
compatible = "simple-audio-card";
label = "tfa9879-mono";
simple-audio-card,dai-link {
/* DAC */
format = "i2s";
bitclock-master = <&dailink_master>;
frame-master = <&dailink_master>;
dailink_master: cpu {
sound-dai = <&ssi2>;
};
codec {
sound-dai = <&codec>;
};
};
};
&i2c1 {
clock-frequency = <400000>;
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_i2c1>;
status = "okay";
codec: tfa9879@6C {
#sound-dai-cells = <0>;
compatible = "tfa9879";
reg = <0x6C>;
};
};
&ssi2 {
fsl,mode = "i2s-master";
status = "okay";
};
the ssi2 node is defined in imx6qdl.dtsi file (no changes).
The SOC is IMX6Q.
The TFA9879 is a slave for I2S transmission.
[*] - I could workaround this problem by setting:
system-clock-frequency = <0> in
dailink_master: cpu {
sound-dai = <&ssi2>;
};
but this is IMHO even worse hack.... than this patch.
I haven't used simple-card for a while so I forgot how to define
its DT bindings specifically. But you should assign ssi2 as the
CPU dai and assign tfa9879 as a CODEC dai.
--
Best regards,
Lukasz Majewski
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