Hello @PatrickF
thank you for the quick response. I tried to replicate the devicetree provided here. Here are the most salient parts related to audio of my devicetree:
sound {
compatible = "audio-graph-card";
label = "AUDIO;
routing =
"HP_OUT", "Digital Input Mux",
"LINE_OUT", "Digital Input Mux",
"AIFOUT", "Capture Mux";
dais = <&sai2a_port &sai2b_port>;
status = "okay";
};
&i2c1{
pinctrl-names = "default", "sleep";
pinctrl-0 = <&i2c1_pins_mx>;
pinctrl-1 = <&i2c1_sleep_pins_mx>;
status = "okay";
/* USER CODE BEGIN i2c1 */
#address-cells = <1>;
#size-cells = <0>;
i2c-scl-rising-time-ns = <100>;
i2c-scl-falling-time-ns = <7>;
/delete-property/dmas;
/delete-property/dma-names;
sgtl5000: codec@0a {
compatible = "fsl,sgtl5000";
reg = <0x0a>;
#sound-dai-cells = <0>;
clocks = <&sai2a>; /* The codec is a consumer of SAI2A master clock */
clock-names = "MCLK";
VDDA-supply = <&v3v3>;
VDDIO-supply = <&v1v8>;
sgtl5000_port: port {
#address-cells = <1>;
#size-cells = <0>;
sgtl5000_tx_endpoint: endpoint@0 {
reg = <0>;
remote-endpoint = <&sai2a_endpoint>;
frame-master; // if I comment these two lines, the audio playback works
bitclock-master;
};
sgtl5000_rx_endpoint: endpoint@1 {
reg = <1>;
remote-endpoint = <&sai2b_endpoint>;
frame-master; // if I comment these two lines, the audio playback works
bitclock-master;
};
};
};
/* USER CODE END i2c1 */
};
&sai2{
pinctrl-names = "default", "sleep";
pinctrl-0 = <&sai2a_pins_mx>, <&sai2b_pins_mx>;
pinctrl-1 = <&sai2a_sleep_pins_mx>, <&sai2b_sleep_pins_mx>;
status = "okay";
/* USER CODE BEGIN sai2 */
clocks = <&rcc SAI2>, <&rcc PLL3_Q>, <&rcc PLL3_R>;
clock-names = "pclk", "x8k", "x11k";
/* USER CODE END sai2 */
sai2a:audio-controller@4400b004{ // Playback DAI
status = "okay";
/* USER CODE BEGIN sai2a */
compatible = "st,stm32-sai-sub-a";
#clock-cells = <0>;
dma-names = "tx";
clocks = <&rcc SAI2_K>;
clock-names = "sai_ck";
sai2a_port: port {
sai2a_endpoint: endpoint {
format = "i2s";
remote-endpoint = <&sgtl5000_tx_endpoint>;
mclk-fs = <256>;
};
};
/* USER CODE END sai2a */
};
sai2b:audio-controller@4400b024{ // Capture DAI
status = "okay";
/* USER CODE BEGIN sai2b */
compatible = "st,stm32-sai-sub-b";
dma-names = "rx";
st,sync = <&sai2a 2>;
clocks = <&rcc SAI2_K>, <&sai2a>;
clock-names = "sai_ck", "MCLK";
sai2b_port: port {
sai2b_endpoint: endpoint {
remote-endpoint = <&sgtl5000_rx_endpoint>;
format = "i2s";
mclk-fs = <256>;
};
};
/* USER CODE END sai2b */
};
};
If I leave lines 40-41 uncommented, both the SAI-A and the codec generate SCK and audio playback does not work. If I leave lines 40-41 commented and lines 48-49 uncommented, the audio playback is heavily disturbed by a high-frequency noise (the source media file is basically unhearable). A working solution for audio playback is to comment lines 40-41 and 48-49, but in these conditions the audio capture does not work, because SCK is not present on the I2S bus.
