Hi Nicolin,
On Tue, Sep 05, 2017 at 11:13:40PM +0200, Łukasz Majewski wrote:
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.
Here is the routine that I understood from the code:
asoc_simple_card_parse_clk_cpu(dev, cpu, dai_link, cpu_dai); => asoc_simple_card_parse_clk(dev, cpu, // cpu node in sound{} [1] dai_link->cpu_of_node, // node ssi2 [2] cpu_dai, dai_link->cpu_dai_name); ==> 1.1) devm_get_clk_from_child(dev, node, NULL); // [1] ==> 1.2) of_property_read_u32(node, "system-clock-frequency", &val)// [1] ==> 1.3) devm_get_clk_from_child(dev, dai_of_node, NULL); // [2]
asoc_simple_card_parse_clk_codec(dev, codec, dai_link, codec_dai); => asoc_simple_card_parse_clk(dev, codec, // codec node in sound{} [3] dai_link->codec_of_node,// node tfa9879 [4] codec_dai, dai_link->codec_dai_name); ==> 2.1) devm_get_clk_from_child(dev, node, NULL); // [3] ==> 2.2) of_property_read_u32(node, "system-clock-frequency", &val)// [3] ==> 2.3) devm_get_clk_from_child(dev, dai_of_node, NULL); // [4]
For the cpu routine, it first checks for clock property under cpu node of simple-card, then for "system-clock-frequency" in the cpu node of simple-card, and finally looks for clock property in ssi2 node.
I've double checked this and the simple_dai->sysclk is assigned in the
asoc_simple_card_parse_clk()
-----> dev: sound -----> clk node: /soc/aips-bus@02000000/spba-bus@02000000/ssi@0202c000 -----> Clk asignment
And this clock is taken from this node. It looks like ipg clock for ssi...
For codec routine, it first checks for clock property under codec node of simple-card, then for "system-clock-frequency" in codec node of simple-card, and finally looks for clock property in the tfa9879 node.
The cpu and codec are totally separate, aren't they? And I don't think it's right if not.
Yes, they should be separated.
which has clock from I2C (66 MHz).
You mean I2C scl or I2S sclk?
I2C scl.
A couple of things here.....
- I don't think I2C scl can run at 66MHz...The 66MHz is probably the ipg clock of I2C controller.
I agree. I2C scl runs with 400 kHz (as recommended by I2C high speed spec).
And considering above, the 66 MHz clock seems to be from ssi IP block.
- Even if the scl does run at 66MHz, there is no point in passing the clock of I2C scl into an I2S dai-link.
Yes.
So I feel something must be wrong. I suggest you to add some printk to check the names of those nodes and x_of_node in the simple card driver.
The problem is with the "lack" of clock nodes/properties at
dailink_master: cpu { sound-dai = <&ssi2>; clock = <&SSSS>; system-clock-frequency = <XXXX>; };
and as a result we take some "default" clock.
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>; }; };I remember there is another style for a single dai-link. Could you please try that one? There is an example in: Documentation/devicetree/bindings/sound/simple-card.txt
Yes, the
simple-audio-card,cpu simple-audio-card,format, ....
etc.
I've omitted it since in the code it is regarded as "old": (simple-card.c line 384).
I think that the proper solution would be to add check for:
freq < sysclk/5 in fsl_ssi_set_dai_sysclk() and return -ENOTSUPP to make the simple-audo-card driver happy (and not introducing regressions).