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IDProjectCategoryView StatusLast Update
0006265fsimx_LinuxKernelpublic2024-06-05 12:49
Reportergerbach Assigned To 
PrioritynormalSeverityminorReproducibilityalways
Status assignedResolutionopen 
Product Versionfsimx6-V3.1 
Target Versionfsimx-next 
Summary0006265: [ALL] It is not possible to read data from serial port when input buffer contains exactly 9 bytes.
DescriptionThe number 9 is related to the length of the rx_fifo_trig in drivers/tty/serial/imx.c. For kernel 5.4.70, it was possible to set this value to 1 in the device tree, but for kernel 5.15.148, this didn't work for me anymore. The new work-around was to disable dma using the "no-dma" setting in device tree. Anyway, this seems like a bug in the serial port implementation which should be fixed.

https://forum.fs-net.de/index.php?thread/4870-cannot-read-serial-port-when-input-buffer-contains-exactly-9-bytes/#post16906
Steps To Reproducefrom serial import Serial
with Serial('/dev/ttymxc2', baudrate=115200, timeout=1) as serial:
    request = b'a' * 9
    serial.write(request)
    response = serial.read(9)
    assert request == response
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