Adding an amplifier to i.MX8QuadMax

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Adding an amplifier to i.MX8QuadMax

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Contributor I

Hi all,

I am trying to add a D class amplifier using esai0, using the simple-audio-card driver and custom codec tas6424.

Firstly, I implemented the i2c interface for codec driver to i2c0_cm41 which is:

 tas6424: tas6424@6a {
       compatible = "ti,tas6424";
       reg = <0x6a>;
       #sound-dai-cells = <0>;
       standby-gpios = <&gpio3 5 GPIO_ACTIVE_LOW>;
       mute-gpios = <&gpio3 27 GPIO_ACTIVE_LOW>;
 };

Then, I added simple-card-audio device tree binding as:

sound-ti-d-class {
        compatible = "simple-audio-card";
        simple-audio-card,name = "TI-D-Class-Amplifier";
        simple-audio-card,mclk-fs = <128>;
        simple-audio-card,format = "i2s";
        simple-audio-card,cpu {
                 sound-dai = <&esai0>;

        };
        simple-audio-card,codec {
                sound-dai = <&tas6424>;

        };        
    };

After doing these, I can see the card by aplay -l as:

card 3: TIDClassAmplifi [TI-D-Class-Amplifier], device 0: 59010000.esai-tas6424-amplifier tas6424-amplifier-0 []
Subdevices: 1/1
Subdevice #0: subdevice #0

and, I can see snd_controls in the alsamixer and able to change these controls.

However, it constantly gives an error:

[ 461.093818] fsl-esai-dai 59010000.esai: failed to derive required HCKT rate
[ 461.100909] asoc-simple-card sound-ti-d-class: ASoC: machine hw_params failed: -22

I examined the fsl_esai.c driver, I concluded that there is a problem with the clock rates. In the amplifier datasheet the clock rates explained as:

     The device supports MCLK rates of 128 × fS , 256 × fS , or 512 × fS .
     The device supports SCLK rates of 32 × f S , 48 × f S or 64 × f S .
     The device supports FSYNC rates of 44.1 kHz, 48 kHz, or 96 kHz.
     The maximum clock frequency is 25 MHz. Therefore, for a 96-kHz FSYNC rate, the maximum MCLK rate is
          256 × fS .
     The MCLK clock must not be in phase to sync to SCLK. Duty cycle of 50% is required for 128x FSYNC, for 256x
         and 512x 50% duty is not required.

How can I set the correct clock rates for the esai interface? I think esai documentation is not mature enough to explain these situations clearly. Is there any comment about this subject?

In case you wonder, the BSP is Linux 4.14.98.

&esai0 {          compatible = "fsl,imx8qm-esai";          pinctrl-names = "default";          pinctrl-0 = <&pinctrl_esai0>;          assigned-clocks = <&clk IMX8QM_ACM_ESAI0_MCLK_SEL>,                  <&clk IMX8QM_AUD_PLL0_DIV>,                  <&clk IMX8QM_AUD_ACM_AUD_PLL_CLK0_DIV>,                  <&clk IMX8QM_AUD_ACM_AUD_REC_CLK0_DIV>,                  <&clk IMX8QM_AUD_ESAI_0_EXTAL_IPG>;          assigned-clock-parents = <&clk IMX8QM_AUD_ACM_AUD_PLL_CLK0_CLK>;          assigned-clock-rates = <0>, <786432000>, <49152000>, <12288000>, <49152000>;          fsl,txm-rxs;          status = "okay"; };

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NXP TechSupport
NXP TechSupport

Hi Yavus

unfortunately i.MX8QM esai simple-audio-card driver is not supported in nxp bsps,

one can try to develop it using general suggestions on

Using ESAI1 Interface to connect I2S from another board as an ALSA card in iMX8QMMEK 

Best regards
igor
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