Electronic – Multiple audio codecs on an i.MX6Q

We are currently trying to bring up a custom i.MX6Q based board with Linux 3.10.17, two TI TLV320AIC3106 codecs and an S/PDIF interface.

The two codecs are I2S slaves and are connected to the i.MX6 via

codec1 <-> AUDMUX3 <-> SSI1

and

codec2 <-> AUDMUX4 <-> SSI2

I have written an ASoC machine driver for the codecs and so far everything looks fine from an ALSA point of view:

aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: imxspdif [imx-spdif], device 0: S/PDIF PCM Playback dit-hifi-0 []
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: CODEC1 [CODEC1], device 0: HiFi tlv320aic3x-hifi-0 []
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 2: CODEC2 [CODEC2], device 0: HiFi tlv320aic3x-hifi-0 []
  Subdevices: 1/1
  Subdevice #0: subdevice #0

arecord -l
**** List of CAPTURE Hardware Devices ****
card 0: imxspdif [imx-spdif], device 1: S/PDIF PCM Capture dir-hifi-1 []
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: CODEC1 [CODEC1], device 0: HiFi tlv320aic3x-hifi-0 []
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 2: CODEC2 [CODEC2], device 0: HiFi tlv320aic3x-hifi-0 []
  Subdevices: 1/1
  Subdevice #0: subdevice #0

My problem now is, that I can only interact with of the codec audio devices (card 2 in the example above). Trying to playback to/capture from card 1 will result in:

aplay -D "plughw:1,0" /home/1000_loud.wav
ALSA sound/core/pcm_lib.c:1944 playback write error (DMA or IRQ trouble?)
aplay: pcm_write:1603: write error: Input/output error

I took notice that I don't have any activity on the I2S lines for card 1 (no clock or data).
However both of the devices do work if I disable the other device in the DT. So I think I must be blocking something somewhere, but I have no idea where/why/how.

I can talk to the codecs via I2C so at least the I2C bus doesn't seem to be the problem.

Here is (the relevant part of) my DT:

/ {

    clocks {
        osc {
            compatible = "fsl,imx-osc", "fixed-clock";
            clock-frequency = <25000000>;
        };
    };

    regulators {
        compatible = "simple-bus";

        reg_audio: tlv320aic3x_supply {
            compatible = "regulator-fixed";
            regulator-name = "tlv320aic3x-supply";
            regulator-boot-on;
            regulator-always-on;
        };
    };

    sound1 {
        compatible = "fsl,imx-audio-tlv320aic3x";
        model = "CODEC1";
        ssi-controller = <&ssi1>;
        audio-codec = <&codec1>;
        audio-routing =
            "Microphone 1",      "LINE1L",
            "Microphone 1",      "LINE1R",
            "Microphone 2",      "LINE2L",
            "Microphone 2",      "LINE2R",
            "Piezo Loudspeaker", "LLOUT";
        mux-int-port = <1>;
        mux-ext-port = <3>;
    };

    sound2 {
        compatible = "fsl,imx-audio-tlv320aic3x";
        model = "CODEC2";
        ssi-controller = <&ssi2>;
        audio-codec = <&codec2>;
        audio-routing =
            "Microphone 1", "LINE1L",
            "Microphone 1", "LINE1R",
            "Microphone 2", "LINE2L",
            "Microphone 2", "LINE2R",
            "Loudspeaker",  "LLOUT",
            "Loudspeaker",  "RLOUT";
        mux-int-port = <2>;
        mux-ext-port = <4>;
    };

    sound-spdif {
        compatible = "fsl,imx-audio-spdif";
        model = "imx-spdif";
        spdif-controller = <&spdif>;
        spdif-in;
        spdif-out;
    };
};

&audmux {
    pinctrl-names = "default";
    pinctrl-0 = <&pinctrl_audmux_4>;
    status = "okay";
};

&i2c1 {
    clock-frequency = <100000>;
    pinctrl-names = "default";
    pinctrl-0 = <&pinctrl_i2c1_2>;
    status = "okay";

    codec1: tlv320aic3x@01b {
        compatible = "ti,tlv320aic3x";
        reg = <0x01b>;
        gpio-reset = <&gpio5 18 GPIO_ACTIVE_LOW>;
        status = "okay";

        clocks = <&clks 201>;
        clock-names = "cko";
        clock-frequency = <25000000>;

        AVDD-supply = <&reg_audio>;
        IOVDD-supply = <&reg_audio>;
        DRVDD-supply = <&reg_audio>;
        DVDD-supply = <&reg_audio>;
        HPVDD-supply = <&reg_audio>;
        SPRVDD-supply = <&reg_audio>;
        SPLVDD-supply = <&reg_audio>;
    };

    codec2: tlv320aic3x@018 {
        compatible = "ti,tlv320aic3x";
        reg = <0x018>;
        gpio-reset = <&gpio5 18 GPIO_ACTIVE_LOW>;
        status = "okay";

        clocks = <&clks 201>;
        clock-names = "cko";
        clock-frequency = <25000000>;

        AVDD-supply = <&reg_audio>;
        IOVDD-supply = <&reg_audio>;
        DRVDD-supply = <&reg_audio>;
        DVDD-supply = <&reg_audio>;
        HPVDD-supply = <&reg_audio>;
        SPRVDD-supply = <&reg_audio>;
        SPLVDD-supply = <&reg_audio>;
    };
};

&iomuxc {
    pinctrl-names = "default";
    pinctrl-0 = <&pinctrl_audmux_4>;

    audmux {
        pinctrl_audmux_4: audmux-4 {
            fsl,pins = <
                MX6QDL_PAD_SD2_DAT0__AUD4_RXD  0x130b0
                MX6QDL_PAD_SD2_DAT3__AUD4_TXC  0x130b0
                MX6QDL_PAD_SD2_DAT2__AUD4_TXD  0x110b0
                MX6QDL_PAD_SD2_DAT1__AUD4_TXFS 0x130b0
                MX6QDL_PAD_CSI0_DAT7__AUD3_RXD  0x130b0
                MX6QDL_PAD_CSI0_DAT4__AUD3_TXC  0x130b0
                MX6QDL_PAD_CSI0_DAT5__AUD3_TXD  0x110b0
                MX6QDL_PAD_CSI0_DAT6__AUD3_TXFS 0x130b0
            >;
        };
    };

    spdif {
        pinctrl_spdif_3: spdifgrp-3 {
            fsl,pins = <
                MX6QDL_PAD_EIM_D21__SPDIF_IN  0x1b0b0
                MX6QDL_PAD_EIM_D22__SPDIF_OUT 0x1b0b0
            >;
        };
    };
};

&ssi1 {
    fsl,mode = "i2s-master";
    status = "okay";
};

&ssi2 {
    fsl,mode = "i2s-master";
    status = "okay";
};

&spdif {
    pinctrl-names = "default";
    pinctrl-0 = <&pinctrl_spdif_3>;
    status = "okay";
};

Does anyone have an idea what I might be missing or doing wrong?

Thanks a lot for any help in advance!