imx-spdif - samplerate is off

[carotte]

Hi,

I am currently facing a strange problem with the SPDIF output on IMX6ULL.

Instead of being 44,1kHz, my AP shows it as 44,8343kHz. This causes some applications to stutter.

Apart from that, SPDIF does work.

Any ideas ?

Thanks!

[igorpadykov]

Hi Noel

what bsp used in the case, one can look at i.MX6ULL spdif example on

https://source.codeaurora.org/external/imx/linux-imx/tree/arch/arm/boot/dts/imx6ull-14x14-ddr3-arm2....

Best regards
igor

[carotte]

Hi Igor,

im currently using the 5.4.70_2.3.0 BSP.

I implemented SPDIF as described - that is not the problem.

The problem is -as I mentioned- that SPDIF works, but the sample rate is not right

[igorpadykov]

was asrc used in the case:

https://source.codeaurora.org/external/imx/linux-imx/tree/arch/arm/boot/dts/imx6ull.dtsi?h=imx_4.19....

one can try to test with unit tests:

https://source.codeaurora.org/external/imx/imx-test/tree/test/mxc_spdif_test?h=imx_5.4.70_2.3.0

Best regards
igor

[carotte]

The SRC is not used.

The test failed as described....

[igorpadykov]

>The SRC is not used.

this may be the reason, may be recommended to port asrc using below example

https://source.codeaurora.org/external/imx/linux-imx/tree/arch/arm/boot/dts/imx6ull-14x14-ddr3-arm2....

Best regards
igor

[carotte]

could you please elaborate on what this example is supposed to show ?

in that device tree I see no reference at all to SPDIF or ASRC, apart from the pin config for SPDIF.

[igorpadykov]

>could you please elaborate on what this example is supposed to show ?

it is in "imx6ull.dtsi" included in that example (imx6ull-14x14-ddr3-arm2.dts) :

https://source.codeaurora.org/external/imx/linux-imx/tree/arch/arm/boot/dts/imx6ull.dtsi?h=imx_4.19....

 

Best regards
igor

[carotte]

The ASRC and SPDIF parts of this device tree are identical to mine.

In the 5.4.7 BSP, this has moved to the 6ul dtsi. The SPDIF part was omitted in this BSP and added by patch.

The ASRC part has not changed. 

So this can't be the reason either. 

Unless there is some other configuration that needs to be done.

[igorpadykov]

when testing with unit tests, had you used Audio Mixer controls:

https://source.codeaurora.org/external/imx/imx-test/tree/test/mxc_spdif_test?h=imx_5.4.70_2.3.0

they are described in sect.7.5 Audio Mixer (AUDMIX)   i.MX Linux Reference Manual​

https://source.codeaurora.org/external/imx/imx-test/tree/test/mxc_amix_test?h=imx_5.4.70_2.3.0

Best regards
igor