From: Oliver Neukum <oneukum@suse.com>
To: Joakim Tjernlund <Joakim.Tjernlund@infinera.com>,
"linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>
Subject: Re: ttyACM and BREAK chars ?
Date: Thu, 12 Sep 2019 10:30:05 +0200 [thread overview]
Message-ID: <1568277005.4008.6.camel@suse.com> (raw)
In-Reply-To: <6e35e841122c1053ce0ec63383a883c7f58fca06.camel@infinera.com>
Am Donnerstag, den 12.09.2019, 07:09 +0000 schrieb Joakim Tjernlund:
> On Wed, 2019-09-11 at 20:27 +0200, Oliver Neukum wrote:
> > Am Mittwoch, den 11.09.2019, 14:34 +0000 schrieb Joakim Tjernlund:
> > > On Wed, 2019-09-11 at 16:22 +0200, Oliver Neukum wrote:
> > > > CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you recognize the sender and know the content is safe.
> > > >
> > > >
> > > > Am Mittwoch, den 11.09.2019, 12:39 +0000 schrieb Joakim Tjernlund:
> > > > > Every now and then my ttyACM0 hangs up or sends a BREAK char to my device.
> > > > > I am trying to make ttyACM ignore incoming(over USB) and not emit
> > > > > any BREAK automatically using termios (IGN_BRK) but that does not make a difference.
> > > > >
> > > > > Is BREAK handling unimpl. in ttyACM ?
> > > >
> > > > acm_send_break() implements it.
> > >
> > > Yes, I se that funktion but I don't see how one can ignore received BREAKs
> > > If I set IGN_BRK on /dev/ttyACM0 I expect that every BREAK should just be ignored
> >
> > Handling breaks looks a bit broken on CDC-ACM.
> > Could you test the attached patch?
> >
>
> Sure, I can test it but from looking at the patch it seems like ACM already ignores
> BREAKs(hardcoded) and with your patch you actually start reporting them.
Well, what is not reported cannot really be ignored.
AFAICT n_tty_receive_break() should solve the issue generically.
> My problem is sudden disconnects I cannot explain but I think they are connect to BREAKs
> I have seen these errors in dmesg though, not sure if they help the diagnose:
> [181780.167987] usb usb1-port6: disabled by hub (EMI?), re-enabling...
The relevant fault happens likely just before that.
> [181780.168208] cdc_acm 1-6.3:1.1: acm_ctrl_irq - usb_submit_urb failed: -19
> [181780.167996] usb 1-6: USB disconnect, device number 30
> [181780.176548] usb 1-6-port2: attempt power cycle
> [181781.772847] usb 1-6.3: USB disconnect, device number 32
> [181781.773134] cdc_acm 1-6.3:1.1: failed to set dtr/rts
Either your cabling is indeed crap, or something crashes your device.
Regards
Oliver
prev parent reply other threads:[~2019-09-12 8:45 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-11 12:39 ttyACM and BREAK chars ? Joakim Tjernlund
2019-09-11 14:22 ` Oliver Neukum
2019-09-11 14:34 ` Joakim Tjernlund
2019-09-11 18:27 ` Oliver Neukum
2019-09-12 7:09 ` Joakim Tjernlund
2019-09-12 8:30 ` Oliver Neukum [this message]
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