Re: rt_dev_send() stalls periodic task

[Jeff Webb <w1@codecraftsmen.org>]

> The only difference in the serial configuration between that cross-link.c
> app and my app was :
> struct rtser_config :
>          .rx_timeout        = RTSER_DEF_TIMEOUT  // infinite ,  no stall for
> many hours in cross-link.c
> versus:
>          .rx_timeout        = 500000   // 500us, stalls within an hour in my
> app
> I don't know why an RX setting affects TX behavior. I also can't use
> RTSER_DEF_TIMEOUT in my application or it dies when it starts up - no clue
> why.  But I did try setting
>    .rx_timeout        = 5000000   // 5 ms. my app doesnt stall for several
> hours

This may not be related, but this jogged my memory about a problem I had years ago regarding rx/tx timeouts affecting the other operation.  I just took a look at rt_16550_write(), and I see:

  rtdm_toseq_init(&timeout_seq, ctx->config.rx_timeout);

  /* Make write operation atomic. */
  ret = rtdm_mutex_timedlock(&ctx->out_lock, ctx->config.rx_timeout,
     &timeout_seq);

This is the same code as in *_read().  I am wondering if this is a cut and paste error.  It seems like these two lines should use tx_timeout instead, but I haven't looked into the code in detail.  Maybe this is related, or maybe another bug?

Thanks,

-Jeff Webb