WM8904 audio codec dts configuration for imx6ull

[francesco_cenci]

Hello All,

I'm working with a MYS-6ULX-IOT board from MyirTech. The board is equipped with a i.mx6ull processor.

I'm trying to use the WM8904 audio codec available with the productor expansion board  "MYB-6ULX Expansion Board"

root@hst:/home/hst# aplay -l
aplay: device_list:268: no soundcards found...

I'm using a custom Debian filesystem ( Debian 8) with the official MyirTech's U-Boot and kernel (linux 4.1.15).

I've recompiled kernel with

cd /home/xubuntu/MYS6ULx-devel/kernel-4.1.15
export DEV_ROOT=~/MYS6ULx-devel
export PATH=$DEV_ROOT/gcc-linaro-4.9-2014.11-x86_64_arm-linux-gnueabihf/bin:$PATH
export CROSS_COMPILE=arm-linux-gnueabihf-
export ARCH=arm

make distclean
make mys_imx6_defconfig
make menuconfig

Throug menuconfig, i've loaded the .config file created with "make mys_imx6_defconfig" and theese flags are checked:

          "Device Drivers > Sound card support > Advanced Linux Sound Architecture > ALSA for SoC audio support > SoC Audio for Freescale CPUs > Symbol: SND_SOC_IMX_WM8904 [=y]  "

           Device Drivers > I2C support > I2C device interface     

           Device Drivers > I2C support > I2C bus multiplexing support     

I also edited the file "imx6ull-14x14-evk.dts" by adding the following lines:

&i2c2 {
clock_frequency = <100000>;
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_i2c2>;
status = "okay";
       codec: wm8904@1a {
       compatible = "wlf,wm8904";
       reg = <0x1a>;
       clocks = <&clks IMX6UL_CLK_SAI2>;
        clock-names = "mclk";
        }; 
};

make zImage dtbs modules

I can use i2sedetect -y 1 to find the audio device at address <0x1a>:

     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:  -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- UU -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --

root@hst:/home/hst# dmesg | grep i2c
[    0.280365] i2c i2c-1: IMX I2C adapter registered
[    0.280406] i2c i2c-1: can't use DMA
[    1.365824] msg ft5x0x_i2c_rxdata i2c read error: -5

[    1.402050] i2c /dev entries driver

root@hst:/home/hst# dmesg | grep wm8904
[    1.796089] wm8904 1-001a: revision A

What am I missing?

The complete .dts file and the boot sequence is in the attachment

Thank you very much in advice,

Francesco

[igorpadykov]

Hi Francesco

one can check sect.7.1.4.1 ASoC Driver Source Architecture

attached Linux Manual and try to debug it starting with codec driver described in

Table 7-1. Stereo Codec SoC Driver Files, create something like imx-wm8904.c

driver and debug it starting from probe function. Check i2c communication with oscilloscope.

Best regards
igor
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