MAX98390 Linux Driver with Alsa

The problem is : failed to derive required Tx rate: 1411200

and is coming from this line in NXP sai drivers.

It looks like you're configuring the I2S interface in device-tree for dai-tdm-slot-num = <2>; dai-tdm-slot-width = <16>;

If the audio file you're trying to play has a sampling rate of 44100 Hz then 2*16*44100 = 1411200 Hz exactly the bit-rate you're requesting to the SAI interface but it is not able to obtain.

I think it is not able to obtain it because it requires integer division from the 24576000 Hz MCLK rate you're setting in &sai1 node.

So you either use audio files with 48Khz sample rate and in that case 2*16*48000 = 1536000 * 16 = 24576000 Hz or you set in &sai1 node the MCLK to some multiple of 44100 Hz like 22579200 Hz.

Regards,

Bogdan

Hi Bogdan,

Thank you for your reply.

I changed the assigned-clock-rates = <24576000>;

&sai1 {
#sound-dai-cells = <0>;
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_sai1>;
assigned-clocks = <&clk IMX8MP_CLK_SAI1>;
assigned-clock-parents = <&clk IMX8MP_AUDIO_PLL1_OUT>;
assigned-clock-rates = <24576000>;
clocks = <&audio_blk_ctrl IMX8MP_CLK_AUDIO_BLK_CTRL_SAI1_IPG>, <&clk IMX8MP_CLK_DUMMY>,
<&audio_blk_ctrl IMX8MP_CLK_AUDIO_BLK_CTRL_SAI1_MCLK1>, <&clk IMX8MP_CLK_DUMMY>,
<&clk IMX8MP_CLK_DUMMY>;
clock-names = "bus", "mclk0", "mclk1", "mclk2", "mclk3";
/*assigned-clock-rates = <0>, <786432000>, <49152000>, <12288000>, <49152000>;*/
fsl,mode = "i2s-master";
fsl,sai-mclk-direction-output;
status = "okay";
};

But still, I am having the same issue. But I noticed that there is no soundcard.

# aplay test.wav
[ 314.624387] fsl-sai 30c10000.sai: failed to derive required Tx rate: 1411200
[ 314.631463] fsl-sai 30c10000.sai: ASoC: error at snd_soc_dai_hw_params on 30c10000.sai: -22
[ 314.639834] 30c10000.sai-max98390-aif1: ASoC: error at __soc_pcm_hw_params on 30c10000.sai-max98390-aif1: -22
ALSA lib /usr/src/debug/alsa-lib/1.2.8-r0/src/pcm/pcm_direct.c:1336:(snd1_pcm_direct_initialize_slave) unable to install hw params
ALSA lib /usr/src/debug/alsa-lib/1.2.8-r0/src/pcm/pcm_dmix.c:1011:(snd_pcm_dmix_open) unable to initialize slave
aplay: main:831: audio open error: Invalid argument

# dmesg | grep -E "fsl|sound|snd"
[ 2.807525] No soundcards found.
[ 314.624387] fsl-sai 30c10000.sai: failed to derive required Tx rate: 1411200
[ 314.631463] fsl-sai 30c10000.sai: ASoC: error at snd_soc_dai_hw_params on 30c10000.sai: -22

Thanks

Chris

Hi,

Take this as reference. Is a limitation of the SAI.

I was suggesting to replace 
assigned-clock-rates = <24576000>;
with
assigned-clock-rates = <22579200>;

but I think you may need to use PLL2 for 44.1Khz sampling rates. Better ask on NXP forum for exact solution.

Thank you Bogdan.

Hi Bogdan,

IMX8MP_AUDIO_PLL2_OUT and 22579200 fixed the issue. I am having sound now. Thank you so much for your help.

&sai1 {
#sound-dai-cells = <0>;
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_sai1>;
assigned-clocks = <&clk IMX8MP_CLK_SAI1>;
assigned-clock-parents = <&clk IMX8MP_AUDIO_PLL2_OUT>;
assigned-clock-rates = <22579200>;
clocks = <&audio_blk_ctrl IMX8MP_CLK_AUDIO_BLK_CTRL_SAI1_IPG>, <&clk IMX8MP_CLK_DUMMY>,
<&audio_blk_ctrl IMX8MP_CLK_AUDIO_BLK_CTRL_SAI1_MCLK1>, <&clk IMX8MP_CLK_DUMMY>,
<&clk IMX8MP_CLK_DUMMY>;
clock-names = "bus", "mclk0", "mclk1", "mclk2", "mclk3";
/*assigned-clock-rates = <0>, <786432000>, <49152000>, <12288000>, <49152000>;*/
fsl,mode = "i2s-master";
fsl,sai-mclk-direction-output;
status = "okay";
};
 

Thanks

Chris