All of lore.kernel.org
 help / color / mirror / Atom feed
From: C Smith <csmithquestions@gmail.com>
To: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Steve Freyder <steve@freyder.net>,
	"xenomai@xenomai.org" <xenomai@xenomai.org>
Subject: Re: rt_dev_send() stalls periodic task
Date: Tue, 23 Apr 2019 23:53:46 -0700	[thread overview]
Message-ID: <CA+K1mPHHO516ziTro8541em4zycwj9pRDo5v-Dd88HQ49kUyXg@mail.gmail.com> (raw)
In-Reply-To: <dccf6d29-e996-5c78-93fe-a74879270a44@siemens.com>

Thanks very much Jan, I'll try your patch tomorrow.

In the meantime it may confirm your suspicions to hear this :
I hacked the xeno_16550A.c driver to poll the transmit buffer every time
there was an RX interrupt (I have a bidirectional application). If there
was any data waiting just call the TX interrupt routine again. Essentially:
if (ctx->out_npend > 0)
   rt_16550_tx_interrupt(ctx)
With this modified driver I was able to stream data successfully without
any stalls for 8+ hours. An oscilloscope showed there were only occasional
delays in sending the data, like an extra 800us.
That seems to confirm that the UART is still functioning OK at the hardware
level during the problem, it just needs to be "reminded" to transmit. Your
patch may be all it needs...

-C Smith

  reply	other threads:[~2019-04-24  6:53 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-15 17:28 rt_dev_send() stalls periodic task C Smith
2019-04-16  8:03 ` Jan Kiszka
2019-04-18  6:42   ` C Smith
2019-04-18  8:36     ` Jan Kiszka
2019-04-21  4:33       ` C Smith
2019-04-21 20:10         ` Steve Freyder
2019-04-22  6:40           ` C Smith
2019-04-22  6:45             ` Jan Kiszka
2019-04-22 19:51               ` Steve Freyder
2019-04-22 20:58                 ` Steve Freyder
2019-04-22 22:56                   ` C Smith
2019-04-22 23:44                     ` Steve Freyder
2019-04-23 12:15               ` Jan Kiszka
2019-04-24  6:53                 ` C Smith [this message]
2019-04-25  7:15                 ` C Smith
2019-04-25  8:23                   ` Jan Kiszka
2019-04-26  0:59                     ` C Smith
2019-04-26 16:38                       ` Jan Kiszka
2019-04-24 13:05 Jeff Webb
2019-04-24 14:36 ` Jan Kiszka
2019-04-26  0:41   ` Jeff Webb

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=CA+K1mPHHO516ziTro8541em4zycwj9pRDo5v-Dd88HQ49kUyXg@mail.gmail.com \
    --to=csmithquestions@gmail.com \
    --cc=jan.kiszka@siemens.com \
    --cc=steve@freyder.net \
    --cc=xenomai@xenomai.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.