From: Johan Hovold <johan@kernel.org>
To: Nix <nix@esperi.org.uk>
Cc: Paul Martin <pm@debian.org>, Oliver Neukum <oliver@neukum.org>,
Johan Hovold <jhovold@gmail.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-kernel@vger.kernel.org
Subject: Re: [3.16.1 BISECTED REGRESSION]: Simtec Entropy Key (cdc-acm) broken in 3.16
Date: Sun, 12 Oct 2014 20:58:45 +0200 [thread overview]
Message-ID: <20141012185845.GB2786@localhost> (raw)
In-Reply-To: <87y4smz1l0.fsf@spindle.srvr.nix>
On Sat, Oct 11, 2014 at 11:24:59PM +0100, Nix wrote:
> On 11 Oct 2014, Paul Martin spake thusly:
>
> > Having been privy to the firmware of the eKey, it is very simplisting,
> > with no implementation whatsoever of any flow control.
>
> That's what I thought. (Why would something that just provides data at a
> constant rate way below that of even the slowest USB bus *need* flow
> control?)
>
> One presumes therefore that the kernel suddenly trying to do flow
> control on shutdown would fubar the firmware's internal state, leading
> to the symptoms I see.
The cdc-acm driver was dropping DTR/RTS on shutdown (close) also before
the commit you refer to. One thing it did change however is that this is
now only done if HUPCL is set. Might setting that flag be enough to
prevent the device firmware from crashing?
Johan
next prev parent reply other threads:[~2014-10-12 18:56 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-31 23:07 [3.16.1 REGRESSION]: Simtec Entropy Key (cdc-acm) broken in 3.16 Nix
2014-09-01 11:09 ` Oliver Neukum
2014-09-04 23:40 ` Nix
2014-09-05 7:59 ` Oliver Neukum
2014-09-05 15:17 ` Nix
2014-09-08 7:21 ` Oliver Neukum
2014-09-08 7:58 ` Nix
2014-10-11 19:05 ` [3.16.1 BISECTED " Nix
2014-10-11 19:51 ` Paul Martin
2014-10-11 22:24 ` Nix
2014-10-12 11:14 ` Paul Martin
2014-10-12 18:58 ` Johan Hovold [this message]
2014-10-12 21:36 ` Nix
2014-10-14 8:34 ` Johan Hovold
2014-10-14 14:44 ` Nix
2014-10-17 13:21 ` Nix
2014-10-19 13:45 ` Johan Hovold
2014-10-22 9:31 ` Nix
2014-10-22 10:14 ` Johan Hovold
2014-10-22 14:00 ` Nix
2014-10-22 15:36 ` Nix
2014-10-24 11:14 ` Johan Hovold
2014-10-24 15:08 ` Nix
2014-10-31 16:44 ` Nix
2014-11-05 11:56 ` Johan Hovold
2014-11-05 15:14 ` Nix
2014-11-05 15:46 ` Daniel Silverstone
2014-11-05 18:14 ` Johan Hovold
2014-11-06 13:49 ` Nix
2014-11-06 17:04 ` Johan Hovold
2014-11-06 17:08 ` [PATCH] USB: cdc-acm: add quirk for control-line state requests Johan Hovold
2014-11-07 9:05 ` Oliver Neukum
2014-11-07 9:16 ` Johan Hovold
2014-11-07 10:23 ` Oliver Neukum
2014-11-06 17:14 ` [3.16.1 BISECTED REGRESSION]: Simtec Entropy Key (cdc-acm) broken in 3.16 Nix
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