I'm getting an overrun error at this point and not an underflow. I am also
measuring 24MHz on MCLK regardless of what I specify.
These clocks are defined within the default am335x-boneblack.dtb. I pay
special attention to the clk_mcasp0 as it specified the gpio-gate-clock
which uses external oscillator, Y4, on the BBB to generate that signal.
I've attempted modifying the clock-frequency value but it does not have an
effect, I still see 24MHz on the output.
clk_mcasp0_fixed {
#clock-cells = <0x0>;
compatible = "fixed-clock";
clock-frequency = <0x1770000>;
linux,phandle = <0x51>;
phandle = <0x51>;
};
clk_mcasp0 {
#clock-cells = <0x0>;
compatible = "gpio-gate-clock";
clocks = <0x51>;
enable-gpios = <0x48 0x1b 0x0>;
linux,phandle = <0x54>;
phandle = <0x54>;
};
Also I've specified the clock within the simple-card binding as follows:
sound_master:simple-audio-card,codec {
sound-dai = <&tlv320aic3104_aq1>;
clocks = <0x54>;
/* system-clock-frequency = <12000000>; */
};
This allows me to use the defined clock, referenced by its phandle, for my
codec. In this configuration it is the codec that is doing the clock
generation as it is defined as the master. In my case, it is generating a
BCLK and a WCLK but at a much higher frequency that what is expected, i.e,
I issue an arecord test.wav, I should see BCLK at 8KHz but it is instead at
16KHz. Or is that what I should expect for BCLK considering Nyquist
Theorem, etc, need to sample at twice the desired frequency? On second
thought, this entire thing is configured for TDM and I am not very familiar
with what I should be seeing vs. what I am seeing.
I'd also like to add that I am seeing data on both AIN and AOUT but its
coming in much faster than we'd expect hence the:
*root@beaglebone:~# arecord test.wavRecording WAVE 'test.wav' : Unsigned 8
bit, Rate 8000 Hz, Monooverrun!!! (at least 0.109 ms long)overrun!!! (at
least 0.064 ms long)overrun!!! (at least 0.754 ms long)*or the
*root@beaglebone:~# speaker-testspeaker-test 1.0.28Playback device is
defaultStream parameters are 48000Hz, S16_LE, 1 channelsUsing 16 octaves of
pink noiseRate set to 48000Hz (requested 48000Hz)Buffer size range from 256
to 32768Period size range from 128 to 16384Using max buffer size
32768Periods = 4was set period_size = 8192was set buffer_size = 32768 0 -
Front LeftWrite error: -32,Broken pipeWrite error: -32,Broken pipeWrite
error: -32,Broken pipeTime per period = 0.101305 0 - Front LeftWrite error:
-32,Broken pipeWrite error: -32,Broken pipeTime per period = 0.054033*
Not sure what to make of the Broken Pipe but there you have it.
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