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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: Mon, 25 May 2020 17:02:57 +0200	[thread overview]
Message-ID: <1590418977.2838.16.camel@suse.com> (raw)
In-Reply-To: <6a4fe396ab5ae6cda548e904c57bc823103999d7.camel@infinera.com>

Am Montag, den 25.05.2020, 14:46 +0000 schrieb Joakim Tjernlund:

> This (EMI?) disconnect causes 2 things.
> 1) I loose the TTY temporarily and have to reconnect.

Unfortunately I see no way to reestablish contact transparantly
on the level of the driver.

> 2) After reconnect there are garbage chars on the gadget side, such as:
>      h�^@^@� ^@^@� ^@

This looks like MM is acting up in user space.

>    or
>      X���)H��4Ğ^���
>    which causes confusion on for the tty/bash on the gadget.
> 
> The disconnect is mostly just annoying but the garbage chars are a major pain, one cannot trust
> that cmds are understod. Is there a bug in ttyACM driver causing these?

Hi,

thanks for the bug report. The most likely cause of your problem is
ModemManager probing the new device. It has a blacklist.

	HTH
		Oliver


  reply	other threads:[~2020-05-25 15:03 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 [this message]
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
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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