topic Audio sai2 mclk in i.MX Processors

Audio sai2 mclk

jieh朱 — Tue, 13 Aug 2019 07:32:18 GMT

Hello, I am using imx6ul, the kernel is linux4.14.78,
I used the i2s external audio chip, but the audio clock is wrong and I can't generate the clock I want. I checked the imx6ul chip manual and found

The register configuration is 10 for PLL4 as the parent clock. But I read it out is 00.
My device tree configures the PLL4 bit parent clock

I should do it exclusively？

Re: Audio sai2 mclk

weidong_sun — Tue, 13 Aug 2019 10:47:53 GMT

Hello Jiehuai,

From source code below, we can know the clock outputs on JTAG_TMS PAD:

    pinctrl_sai2: sai2grp {
       fsl,pins = <
           MX6UL_PAD_JTAG_TDI__SAI2_TX_BCLK   0x17088
           MX6UL_PAD_JTAG_TDO__SAI2_TX_SYNC   0x17088
           MX6UL_PAD_JTAG_TRST_B__SAI2_TX_DATA   0x11088
           MX6UL_PAD_JTAG_TCK__SAI2_RX_DATA   0x11088
           MX6UL_PAD_JTAG_TMS__SAI2_MCLK       0x17088
           MX6UL_PAD_SNVS_TAMPER4__GPIO5_IO04   0x17059
       >;
   };

after system booting is done, you can play a music file, then measure the clock on the JTAG_TMS Pin to check if the clock value is what you want.

(系统启动后，播放一个音乐文件，然后用示波器在这个脚上测一下clock的值是否是你希望的12.288MHz, PLL4配置为786432000Hz，它是12288000Hz的整数倍，配置上是对的，输出的clock应该是正确的。所以，请示波器测量一下，看实际结果)

Have a nice day!
BR,

Weidong

Re: Audio sai2 mclk

jieh朱 — Wed, 14 Aug 2019 02:23:46 GMT

thank you for your reply
After I enable the frequency, I start the error.

Re: Audio sai2 mclk

weidong_sun — Wed, 14 Aug 2019 05:56:52 GMT

Hi Jiehuai,

On i.MX6UL EVK, default I2S port is also SAI2, so you don't need to change source code if you also use the same codec as that of EVK, below is source code in dts:

    pinctrl_i2c2: i2c2grp {
       fsl,pins = <
           MX6UL_PAD_UART5_TX_DATA__I2C2_SCL 0x4001b8b0
           MX6UL_PAD_UART5_RX_DATA__I2C2_SDA 0x4001b8b0
       >;
   };
......

/* Here is sound card , Machine driver will be loaded here */

   sound: sound {
       compatible = "fsl,imx6ul-evk-wm8960",
               "fsl,imx-audio-wm8960";
       model = "wm8960-audio";
       cpu-dai = <&sai2>;
       audio-codec = <&codec>;
       asrc-controller = <&asrc>;
       codec-master;
       gpr = <&gpr 4 0x100000 0x100000>;   /* This is SAI2_MCLK setting in GPR register */
       /*
                 * hp-det = <hp-det-pin hp-det-polarity>;
       * hp-det-pin: JD1 JD2 or JD3
       * hp-det-polarity = 0: hp detect high for headphone
       * hp-det-polarity = 1: hp detect high for speaker
       */
       hp-det = <3 0>;
       hp-det-gpios = <&gpio5 4 0>;
       mic-det-gpios = <&gpio5 4 0>;
       audio-routing =
           "Headphone Jack", "HP_L",
           "Headphone Jack", "HP_R",
           "Ext Spk", "SPK_LP",
           "Ext Spk", "SPK_LN",
           "Ext Spk", "SPK_RP",
           "Ext Spk", "SPK_RN",
           "LINPUT2", "Mic Jack",
           "LINPUT3", "Mic Jack",
           "RINPUT1", "Main MIC",
           "RINPUT2", "Main MIC",
           "Mic Jack", "MICB",
           "Main MIC", "MICB",
           "CPU-Playback", "ASRC-Playback",
           "Playback", "CPU-Playback",
           "ASRC-Capture", "CPU-Capture",
           "CPU-Capture", "Capture";
   };

........

&clks {
assigned-clocks = <&clks IMX6UL_CLK_PLL4_AUDIO_DIV>;
assigned-clock-rates = <786432000>;
};

......

&i2c2 {
   clock_frequency = <100000>;
   pinctrl-names = "default";
   pinctrl-0 = <&pinctrl_i2c2>;
   status = "okay";

   codec: wm8960@1a {
       #sound-dai-cells = <0>;
       compatible = "wlf,wm8960";
       reg = <0x1a>;
       wlf,shared-lrclk;
       clocks = <&clks IMX6UL_CLK_SAI2>;
       clock-names = "mclk";
   };

......
   pinctrl_sai2: sai2grp {
       fsl,pins = <
           MX6UL_PAD_JTAG_TDI__SAI2_TX_BCLK   0x17088
           MX6UL_PAD_JTAG_TDO__SAI2_TX_SYNC   0x17088
           MX6UL_PAD_JTAG_TRST_B__SAI2_TX_DATA   0x11088
           MX6UL_PAD_JTAG_TCK__SAI2_RX_DATA   0x11088
           MX6UL_PAD_JTAG_TMS__SAI2_MCLK       0x17088
           MX6UL_PAD_SNVS_TAMPER4__GPIO5_IO04   0x17059
       >;
   };
......

&sai2 {
   pinctrl-names = "default";
   pinctrl-0 = <&pinctrl_sai2>;
   assigned-clocks = <&clks IMX6UL_CLK_SAI2_SEL>,
              <&clks IMX6UL_CLK_SAI2>;
   assigned-clock-parents = <&clks IMX6UL_CLK_PLL4_AUDIO_DIV>;
   assigned-clock-rates = <0>, <12288000>;
   fsl,sai-mclk-direction-output;
   status = "okay";
};

Are you using i.MX6UL EVK to test it?

BR,

Weidong

Re: Audio sai2 mclk

jieh朱 — Wed, 14 Aug 2019 09:44:58 GMT

thank you for your reply

I look at the clock tree

according to dts

sai2 Parent clock is IMX6UL_CLK_PLL4_AUDIO_DIV

Re: Audio sai2 mclk

weidong_sun — Thu, 15 Aug 2019 01:43:47 GMT

Are you using i.MX6UL EVK to test it?

weidong