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AM3354: Uart overrun issue

Biao Li
Expert 6440 points
Part Number: AM3354

Tool/software:

Hi Expert,

customer is using AM3354 and using 115200 baud rate before, now they want to increase the baud rate to 1Mbps, but it will report overrun issue, the log as attach, and customer also try enable the DMA mode, it will be improved but still have overrun error, can you help give some suggestion to customer? previous customer is using the open source kernel v5.10, I let customer using SDK7.3 now. the issue still here, we can debug this issue based on SDK7.3. 

172.21.25.224_2025-08-27_15-21-01.log

BR,

Biao 

  • 0
    TI__Guru**** 168311 points

    Hi Biao,

    In general, UART RX overrun issue could happen if hardware flow control is not enabled.

    Please ask the customer to test with the latest SDK for AM335x - SDK9.3 to see if the issue still happens, then we will debug from there.

  • 0 in reply to Bin Liu
    TI__Expert 6440 points

    Hi Bin,

    Customer can’t connect Flow control because the HW is fixed, I will let customer try the latest kernel, but if latest kernel still have issues, can you provide some suggestions just like increase the priority of UART interrupt? Do you think this will help or not?

    BR,

    Biao

  • 0 in reply to Biao Li
    TI__Guru**** 168311 points

    Hi Biao,

    We would have to know the details of the problem, such as the symptoms, UART usage, and test method, etc, to know how to resolve it, if possible.

  • 0 in reply to Bin Liu
    TI__Expert 6440 points

    Hi Bin,

    customer is using Uart0 and Uart2 to receive the packet from other SOC, and due to the HW flow control signal can't be connected to other SOC, so they only connect the RX TX, it can work normally when the baud rate is 115200, but when they increase the baud rate to 1Mbps, serval minutes later, the packet will be partitional. and the kernel will report the overrun error as below.  if you need any more detail pls let me know, I will try to figure it out.

    [ 654.430003] ttyO ttyO2: 1 input overrun(s)
    [ 749.040763] ttyO ttyO2: 1 input overrun(s)
    [ 832.860047] ttyO ttyO2: 3 input overrun(s)

    BR,

    Biao 

  • 0 in reply to Biao Li
    TI__Expert 6440 points

    Hi Bin,

    can AM335 support uart polling mode? if can support pls share some code reference to us, and customer is asking for increase the priority of UART interrupt, can you also give some guide?

    BR,

    Biao 

  • +1 in reply to Biao Li
    TI__Guru**** 168311 points

    Hi Biao,

    Biao Li said:
    [ 654.430003] ttyO ttyO2: 1 input overrun(s)

    I am not sure the kernel version would improve the issue. Has the customer tried with RT Linux? RT Linux typically has better latency.

    If the customer uses non-RT Linux, what is the cpufreq governor setting to? Please set it to "performance" if not yet.

  • 0 in reply to Bin Liu
    TI__Expert 6440 points

    Hi Bin,

    Thanks for support, customer is using balance mode, and after change to performance mode, this issue have been fixed. This thread can be closed.

    BR,

    Biao