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AM3356: RS232/RS485 Communication Issue with the 8250 Driver

Godson Thomas
Prodigy 20 points
Part Number: AM3356

Tool/software:

I am currently working with an embedded board featuring the AM3356 processor, running Embedded Linux version 4.14.67. I am in the process of implementing the RS232 protocol with handshaking support, as well as RS485 functionality. To enable the 8250 serial driver instead of default omap serial driver , I modified the kernel configuration file and successfully attached the 8250 driver to the four serial ports. I have attached the relevant log for your reference.

However, I am experiencing stability issues with the new serial driver (8250_port.c) that I incorporated to support hardware flow control in RS232 mode. Specifically, there is a noticeable delay in starting communication after the serial port initialization, and I have encountered communication loss during RS232 operation.

I would appreciate any insights or suggestions you might have regarding this issue.

  • 0
    TI__Guru**** 158921 points

    Hi Godson,

    For TI processors, the UART driver omap-serial.c has been used on old versions of kernel, then later this driver is no longer maintained, and moved to use 8250/8250_omap.c. But I don't recall the exact kernel version in which the driver transition happened, so I unable to comment on which driver you should use on kernel v4.14. The v4.14 is no longer supported on this forum anyway.

    Is there any reason why you don't use Processor SDK v9.1 (currently the latest for AM335x) which has kernel v6.1 on your AM335x project?

  • 0 in reply to Bin Liu
    Prodigy 20 points

    Hi Bin,

    Our embedded firmware has been continuously updated over time, with new features being added with kernel version 4.14.67. We have continued development on this specific version to ensure compatibility. Hence, we have integrated 8250 into this kernel.

  • 0 in reply to Godson Thomas
    TI__Guru**** 158921 points

    Hi Godson,

    Understood.

    As I mentioned kernel v4.14 is no longer supported. But I just checked the SDKv5.1 which uses v4.14.67, the kernel defconfig uses omap-serial.c, not 8250/8250_omap.c. So I suspect you would run into issues if you want to switch to 8250_omap.c driver.