root@j721s2-evm:/data/cache# ls -l
total 144
drwxr-xr-x 3 root root  4096 Sep 19  2025 boot
-rw-r--r-- 1 root root   158 Apr 28 17:45 debug_txt
drwx------ 2 root root 16384 Aug 30  2022 lost+found
-rwxr-xr-x 1 root root 27280 Sep 19  2025 spidev_fdx
-rwxr-xr-x 1 root root 45072 Sep 23  2025 spidev_test
-rwxr-xr-x 1 root root 44176 Sep 19  2025 spidev_test_01
root@j721s2-evm:/data/cache# ./spidev_test -v -D /dev/spidev0.0 -i debug_txt
spi mode: 0x0
bits per word: 8
max speed: 500000 Hz (500 kHz)
[transfer] Line:150.
[transfer] Line:152.
TX | 74 68 65 72 77 69 73 65 2C 20 70 65 72 68 61 70 73 20 74 68 65 20 6C 61 72 67 65 20 43 50 55 20  |therwise, perhaps the large CPU |
TX | 6C 6F 61 64 20 69 73 20 63 61 75 73 65 64 20 62 79 20 74 68 69 73 20 62 6C 6F 63 6B 69 6E 67 20  |load is caused by this blocking |
TX | 63 61 6C 6C 20 74 6F C2 A0 73 70 69 5F 73 79 6E 63 20 61 6E 64 20 44 4D 41 20 69 73 20 61 6C 72  |call to..spi_sync and DMA is alr|
TX | 65 61 64 79 20 73 65 74 20 75 70 3F 0A 77 68 69 63 68 20 69 73 20 74 68 65 20 69 6E 64 75 73 74  |eady set up?.which is the indust|
TX | 72 69 61 6C 20 76 61 72 69 61 6E 74 20 6F 66 20 54 44 41 34 56 45 2E 68 61 77 61 79 69 0A __ __  |rial variant of TDA4VE.hawayi.|
RX | FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF  |................................|
RX | FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF  |................................|
RX | FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF  |................................|
RX | FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF  |................................|
RX | FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF __ __  |..............................|
root@j721s2-evm:/data/cache# vi debug_txt 
root@j721s2-evm:/data/cache# ./spidev_test -v -D /dev/spidev0.0 -i debug_txt
spi mode: 0x0
bits per word: 8
max speed: 500000 Hz (500 kHz)
[transfer] Line:150.
[transfer] Line:152.
TX | 74 68 65 72 77 69 73 65 2C 20 70 65 72 68 61 70 73 20 74 68 65 20 6C 61 72 67 65 20 43 50 55 20  |therwise, perhaps the large CPU |
TX | 6C 6F 61 64 20 69 73 20 63 61 75 73 65 64 20 62 79 20 74 68 69 73 20 62 6C 6F 63 6B 69 6E 67 20  |load is caused by this blocking |
TX | 63 61 6C 6C 20 74 6F C2 A0 73 70 69 5F 73 79 6E 63 20 61 6E 64 20 44 4D 41 20 69 73 20 61 6C 72  |call to..spi_sync and DMA is alr|
TX | 65 61 64 79 20 73 65 74 20 75 70 3F 0A 77 68 69 63 68 20 69 73 20 74 68 65 20 69 6E 64 75 73 74  |eady set up?.which is the indust|
TX | 72 69 61 6C 20 76 61 72 69 61 6E 74 20 6F 66 20 54 44 41 34 56 45 2E 2E 68 61 77 61 79 69 0A __  |rial variant of TDA4VE..hawayi.|
RX | FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF  |................................|
RX | FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF  |................................|
RX | FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF  |................................|
RX | FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF  |................................|
RX | FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF __  |...............................|
root@j721s2-evm:/data/cache# ls -l
total 144
drwxr-xr-x 3 root root  4096 Sep 19  2025 boot
-rw-r--r-- 1 root root   159 Apr 28 17:46 debug_txt
drwx------ 2 root root 16384 Aug 30  2022 lost+found
-rwxr-xr-x 1 root root 27280 Sep 19  2025 spidev_fdx
-rwxr-xr-x 1 root root 45072 Sep 23  2025 spidev_test
-rwxr-xr-x 1 root root 44176 Sep 19  2025 spidev_test_01
root@j721s2-evm:/data/cache# vi debug_txt 
root@j721s2-evm:/data/cache# ./spidev_test -v -D /dev/spidev0.0 -i debug_txt
spi mode: 0x0
bits per word: 8
max speed: 500000 Hz (500 kHz)
[transfer] Line:150.

root@j721s2-evm:/data/cache# ./spidev_test -v -D /dev/spidev0.0 -p "therwise, perhaps the large CPU load is caused by this blocking call spi_sync and DMA is already set up? which is the industrial variant of TDA4VE. hawayi....."
spi mode: 0x0
bits per word: 8
max speed: 500000 Hz (500 kHz)
[main] Line:483.
[transfer_escaped_string] Line:329.
[transfer] Line:150.
[transfer] Line:152.
TX | 74 68 65 72 77 69 73 65 2C 20 70 65 72 68 61 70 73 20 74 68 65 20 6C 61 72 67 65 20 43 50 55 20  |therwise, perhaps the large CPU |
TX | 6C 6F 61 64 20 69 73 20 63 61 75 73 65 64 20 62 79 20 74 68 69 73 20 62 6C 6F 63 6B 69 6E 67 20  |load is caused by this blocking |
TX | 63 61 6C 6C 20 73 70 69 5F 73 79 6E 63 20 61 6E 64 20 44 4D 41 20 69 73 20 61 6C 72 65 61 64 79  |call spi_sync and DMA is already|
TX | 20 73 65 74 20 75 70 3F 20 77 68 69 63 68 20 69 73 20 74 68 65 20 69 6E 64 75 73 74 72 69 61 6C  | set up? which is the industrial|
TX | 20 76 61 72 69 61 6E 74 20 6F 66 20 54 44 41 34 56 45 2E 20 68 61 77 61 79 69 2E 2E 2E 2E 2E __  | variant of TDA4VE. hawayi.....|
RX | FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF  |................................|
RX | FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF  |................................|
RX | FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF  |................................|
RX | FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF  |................................|
RX | FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF __  |...............................|
[transfer_escaped_string] Line:331.
[main] Line:485.
root@j721s2-evm:/data/cache# ./spidev_test -v -D /dev/spidev0.0 -p "therwise, perhaps the large CPU load is caused by this blocking call spi_sync and DMA is already set up? which is the industrial variant of TDA4VE. hawayi......"
spi mode: 0x0
bits per word: 8
max speed: 500000 Hz (500 kHz)
[main] Line:483.
[transfer_escaped_string] Line:329.
[transfer] Line:150.