DFU doesn't work if MIXER disabled while XUD on tile1 and AUDIO IO on tile0

[QuinnWang]

Replicatable on the 316 MC:
1, change the xn file to move audio io from original tile1 to tile0, as attached xk-audio-316-mc.xn.zip
2, change xua_conf_tasks.h: on tile[1] to on tile[XUA_AUDIO_IO_TILE_NUM]
3, change xua_conf.h: XUA_XUD_TILE_NUM to 1, and XUA_AUDIO_IO_TILE_NUM to 0
4, commented out the p_leds in the audiostream.xc
5, use the build option

Audio Class 2, Async, I2S Master, 2xInput, 2xOutput

set(APP_COMPILER_FLAGS_2AMi2o2xxxxxx ${SW_USB_AUDIO_FLAGS} -DI2S_CHANS_DAC=2
-DI2S_CHANS_ADC=2
-DMIXER=1)
then on 316 mc, the USB runs on tile1, audio runs on tile0, no sound output as expected because we are using dummy ports for I2S on tile0. The audio path works well as expected, such as we can simply add a usb2aud loopback to aud2usb buffer to do a usb out -> usb in loopback test, and DFU is okay.
But set -DMIXER=0, the DFU blocked to read out the DFU state in the app mode:

% dfu-util -d 20b1:0016 -D dfu_0x1234.bin -R
dfu-util 0.11

Copyright 2005-2009 Weston Schmidt, Harald Welte and OpenMoko Inc.
Copyright 2010-2021 Tormod Volden and Stefan Schmidt
This program is Free Software and has ABSOLUTELY NO WARRANTY
Please report bugs to http://sourceforge.net/p/dfu-util/tickets/

dfu-util: Warning: Invalid DFU suffix signature
dfu-util: A valid DFU suffix will be required in a future dfu-util release
Opening DFU capable USB device...
Device ID 20b1:0016
Run-Time device DFU version 0110
Claiming USB DFU (Run-Time) Interface...
Setting Alternate Interface zero...
Determining device status...
dfu-util: error get_status: LIBUSB_ERROR_TIMEOUT

[shuchitak]

I can recreate this on the 216 MC, since USB and Audio run on tile 1 and 0 for it, with just compiling the app with -DMIXER=0.
Will debug.

[shuchitak]

Hi @QuinnWang, I've found a workaround for this, which is, running the DFUHandler() and dummy_deliver() in xua_audiohub as separate threads instead of being combined into one thread. Copied the change below. With this, DFU works successfully even when -DMIXER=0. If your application has a spare thread on tile 0, this could work. Is this an option for you?

--- a/lib_xua/src/core/audiohub/xua_audiohub.xc
+++ b/lib_xua/src/core/audiohub/xua_audiohub.xc
@@ -615,7 +615,7 @@ void DFUHandler(server interface i_dfu i, chanend ?c_user_cmd);
 /* This function is a dummy version of the deliver thread that does not
    connect to the codec ports. It is used during DFU reset and during idle non-streaming mode, if enabled.
    Note there are two paths through depending on dfuMode.*/
-[[combinable]]
+//[[combinable]]
 static void dummy_deliver(chanend ?c_aud, unsigned sampFreq, unsigned dfuMode, unsigned &command)
 {
     const int wait_ticks = XS1_TIMER_HZ / sampFreq;
@@ -697,7 +697,7 @@ void check_and_enter_dfu(unsigned curSamFreq, chanend c_aud, server interface i_
         unsigned command = XUA_AUDCTL_NO_COMMAND;
         while (1)
         {
-           [[combine]]
+           //[[combine]]
             par
             {