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: disabled by hub (EMI?), re-enabling... Causes garbage chars & disconnect
Date: Wed, 27 May 2020 12:41:08 +0200 [thread overview]
Message-ID: <1590576068.2838.56.camel@suse.com> (raw)
In-Reply-To: <f4a809ba4ca132266e476ca1805e4ff9e5663f9f.camel@infinera.com>
Am Mittwoch, den 27.05.2020, 09:40 +0000 schrieb Joakim Tjernlund:
> On Wed, 2020-05-27 at 10:38 +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 Dienstag, den 26.05.2020, 17:19 +0000 schrieb Joakim Tjernlund:
> > >
> > > This "u-boot SPL" is the first thing u-boot writes and somehow this is remembered, I assume, by cdc_acm
> > > and gets echoed back when I open ttyACM0
> >
> > Hi,
> >
> > that makes sense, but it is not something that we could really
> > change in CDC-ACM, I am afraid.
>
> Why not? CDC-ACM should echo back anything it has received before open of ttyACM
Well, there is an inherent race condition with loading the module I am
afraid. By default cdc-acm should actually echo. You can set the
DISABLE_ECHO echo quirk for your device if you want to get rid of it.
Is CDC-ACM violating some standard with respect to echoing? Changing
defaults really hurts users, no matter what you do.
Regards
Oliver
next prev parent reply other threads:[~2020-05-27 10:41 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-25 14:46 ttyACM: disabled by hub (EMI?), re-enabling... Causes garbage chars & disconnect Joakim Tjernlund
2020-05-25 15:02 ` Oliver Neukum
2020-05-25 15:15 ` Joakim Tjernlund
2020-05-25 16:49 ` Joakim Tjernlund
2020-05-26 8:47 ` Oliver Neukum
2020-05-26 8:59 ` Joakim Tjernlund
2020-05-26 10:14 ` Oliver Neukum
2020-05-26 16:46 ` Joakim Tjernlund
2020-05-26 17:19 ` Joakim Tjernlund
2020-05-27 8:38 ` Oliver Neukum
2020-05-27 9:40 ` Joakim Tjernlund
2020-05-27 10:12 ` Greg KH
2020-05-27 10:41 ` Oliver Neukum [this message]
2020-05-27 13:16 ` Joakim Tjernlund
2020-05-27 15:41 ` Joakim Tjernlund
2020-06-05 10:09 ` Joakim Tjernlund
2020-06-08 9:13 ` Oliver Neukum
2020-06-08 11:39 ` Joakim Tjernlund
2020-06-08 15:40 ` Oliver Neukum
2020-06-08 16:00 ` Joakim Tjernlund
2020-06-08 19:21 ` Oliver Neukum
2020-06-15 11:01 ` Joakim Tjernlund
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