TDA4VM : McASP and Dummy mode on J7

Hi Experts,

I need to use McASP10 of J7 to do some testing with external device base on no codec device.

MCASP10 AXR0 : input, receive I2S signal from external device
MCASP10 AXR1 : output, Send I2S signal to external device

I set to Dummy mode and play the wav file,

but I can't probe any signal from McASP10 ACLKX and AXR1 with oscilloscope.

Could you give me some advice, 

Thanks and Best Regards,

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Kernel version：Linux j7-evm 5.10.100 #9 SMP PREEMPT Mon May 22 15:43:41 CST 2023 aarch64 aarch64 aarch64 GNU/Linux

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I have referred to these discussions to modify the DTS

https://e2e.ti.com/support/processors-group/processors/f/processors-forum/607500/linux-processor-sdk-am335x-mcasp-master-mode-configuration

https://e2e.ti.com/support/processors-group/processors/f/processors-forum/672205/linux-am3352-mcasp-configuration-for-dummy-codec

https://e2e.ti.com/support/processors-group/processors/f/processors-forum/629979/linux-dra745-mcasp-and-dummy-sound-card-on-dra7xx?tisearch=e2e-sitesearch&keymatch=jacinto

and I tried using "aplay" to check if dummy function is workable

root@j7-evm:~# aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: Dummy [Dummy], device 0: Dummy PCM [Dummy PCM]
Subdevices: 8/8
Subdevice #0: subdevice #0
Subdevice #1: subdevice #1
Subdevice #2: subdevice #2
Subdevice #3: subdevice #3
Subdevice #4: subdevice #4
Subdevice #5: subdevice #5
Subdevice #6: subdevice #6
Subdevice #7: subdevice #7

root@j7-evm:~# aplay /bin/Ring01.wav
Playing WAVE '/bin/Ring01.wav' : Signed 16 bit Little Endian, Rate 22050  Hz, Stereo

After "aplay" the wav file, I can't probe the signal out put on McASP10 ACLKX and FSX.

Checking aplay status, it looks like "aplay" is working,

root@j7-evm:~# aplay /bin/Ring01.wav &
[1] 1248
Playing WAVE '/bin/Ring01.wav' : Signed 16 bit Little Endian, Rate 22050 Hz, Stereo
root@j7-evm:~# cat /proc/asound/card0/pcm0p/sub0/status
state: RUNNING
owner_pid : 1248
trigger_time: 2583.017112615
tstamp : 0.000000000
delay : 10250
avail : 775
avail_max : 8269
-----
hw_ptr : 28336
appl_ptr : 38586
root@j7-evm:~#
root@j7-evm:~# cat /proc/asound/card0/pcm0p/sub0/status
state: RUNNING
owner_pid : 1248
trigger_time: 2583.017112615
tstamp : 0.000000000
delay : 9948
avail : 1077
avail_max : 2756
-----
hw_ptr : 100294
appl_ptr : 110242
root@j7-evm:~#

and I set SND_DUMMY to "y" in defconfig ( "board-support/linux-5.10.100+gitAUTOINC+7a7a3af903-g7a7a3af903/arch/arm64/configs/tisdk_j7-evm_defconfig")

CONFIG_SND_SIMPLE_CARD=y

CONFIG_SND_DUMMY=y

I modified the DTS "k3-j721e-common-proc-board.dts"

codec_test: codec_test {

    compatible = "linux,snd-soc-dummy";
    #sound-dai-cells = <0>;
    status="okay";

};

sound0: sound@0 {

    compatible = "simple-audio-card";
    simple-audio-card,name = "TEST-EVM";
    simple-audio-card,format = "i2s";
    simple-audio-card,bitclock-master = <&sound_master>;
    simple-audio-card,frame-master = <&sound_master>;

    status="okay";
                       
    sound_master: simple-audio-card,cpu {
        sound-dai = <&mcasp10>;
        system-clock-frequency = <24576000>;
    };
    simple-audio-card,codec {
        sound-dai = <&codec_test>;     
    };

};

mcasp10_pins_default: mcasp10-pins-default {
    pinctrl-single,pins = <
        J721E_IOPAD(0x158, PIN_OUTPUT_PULLDOWN, 12) /* (U23) RGMII5_TX_CTL.MCASP10_ACLKX */
        J721E_IOPAD(0x15c, PIN_OUTPUT_PULLDOWN, 12) /* (U26) RGMII5_RX_CTL.MCASP10_AFSX */
        J721E_IOPAD(0x160, PIN_OUTPUT_PULLDOWN, 12) /* (V28) RGMII5_TD3.MCASP10_AXR0 */
        J721E_IOPAD(0x164, PIN_OUTPUT_PULLDOWN, 12) /* (V29) RGMII5_TD2.MCASP10_AXR1 */
    >;
};

&mcasp10 {

    #sound-dai-cells = <0>;
    
    pinctrl-names = "default";
    pinctrl-0 = <&mcasp10_pins_default>;
    
    op-mode = <0>; // MCASP_IIS_MODE
    tdm-slots = <2>;
    auxclk-fs-ratio = <256>;

    serial-dir = < // 0: INACTIVE, 1: TX, 2: RX
        1 2 0 0
    >;
    tx-num-evt = <32>;
    rx-num-evt = <32>;
};

u-boot pin definition "board-support/u-boot-2021.01+gitAUTOINC+44a87e3ab8-g44a87e3ab8/arch/arm/dts/k3-j721e-common-proc-board.dts", 

the MCASP 10 pin definition is the same as the kernel's DTS

mcasp10_pins_default: mcasp10-pins-default {
    pinctrl-single,pins = <
        J721E_IOPAD(0x158, PIN_OUTPUT_PULLDOWN, 12) /* (U23) RGMII5_TX_CTL.MCASP10_ACLKX */
        J721E_IOPAD(0x15c, PIN_OUTPUT_PULLDOWN, 12) /* (U26) RGMII5_RX_CTL.MCASP10_AFSX */
        J721E_IOPAD(0x160, PIN_OUTPUT_PULLDOWN, 12) /* (V28) RGMII5_TD3.MCASP10_AXR0 */
        J721E_IOPAD(0x164, PIN_OUTPUT_PULLDOWN, 12) /* (V29) RGMII5_TD2.MCASP10_AXR1 */
    >;
};

and I add some debug message in "davinci-mcasp.c" th check if the mcasp driver is running.

when system booting, I found the function "mcasp_reparent_fck()" return '0', because it can't get "fck_parent"

parent_name = of_get_property(node, "fck_parent", NULL);
if (!parent_name)
    return 0;

Do you have any suggestions about the system does not get the property parent_name?

Will it cause no signal output of MCASP ACLKX/AXR?