From: Johan Hovold <johan@kernel.org>
To: jakub nantl <jn@forever.cz>
Cc: linux-usb@vger.kernel.org
Subject: Re: ch341 garbage read with 5.5.x kernel
Date: Wed, 5 Feb 2020 08:43:12 +0100 [thread overview]
Message-ID: <20200205074312.GP26725@localhost> (raw)
In-Reply-To: <b23691c8-9219-b360-6114-93e86a8bd997@forever.cz>
On Tue, Feb 04, 2020 at 11:02:04PM +0100, jakub nantl wrote:
> Hi,
>
> I have arduino nano (ch341) connected to my pc and after upgrading
> kernel to 5.5.x I am getting garbage instead of text while reading it
> (with both 5.5.1 and 5.5.2 kernels):
>
> Feb 4 09:24:20 sopa read.pl[2070]: StX.XXA(aurXXXŅstXC#021XX XJXR
> FuX,#027XX#005
> Feb 4 09:24:20 sopa read.pl[2070]: XtX,+XX HXX#026XX go.XXRXXXXXng*Xery
> XXX5XUXiXY'XX4
> Feb 4 09:24:20 sopa read.pl[2070]: XP5逮#013XXteXX11XS4
> Feb 4 09:24:20 sopa read.pl[2070]:
> XP5逮#013XXhuXZ.XX=6SHX#005XAXXXpXKVX}XXt=MXXj
> Feb 4 09:24:20 sopa read.pl[2070]: DXUu X#013X-XXXXXeXNMSX
> Feb 4 09:24:20 sopa read.pl[2070]: XP)}XNXC
>
> with 5.4.17 I get:
>
> Feb 4 22:43:10 sopa read.pl[2040]: Started (auriol_last)
> Feb 4 22:43:11 sopa read.pl[2040]: Reporting every 300s
> Feb 4 22:43:11 sopa read.pl[2040]: Uptime: 60
> Feb 4 22:43:11 sopa read.pl[2040]: DATA: sopa-temp=11.21
> Feb 4 22:43:11 sopa read.pl[2040]: DATA: sopa-humidity=60
> Feb 4 22:43:11 sopa read.pl[2040]: DATA: sopa-dewpoint=3.68
> Feb 4 22:43:11 sopa read.pl[2040]: DATA: sopa-pressure=97136
> Feb 4 22:43:11 sopa read.pl[2040]: DATA_END
>
> any suggestions?
There were some fixes to the baudrate handling that went into 5.5 that
are likely related to this.
These changes provide more accurate output rates, but I have since
received one report that it may inadvertently have made the device more
sensitive to errors in the input rate. In that case, the reporter
switched to a baudrate that matches his actual rate which was 117647
rather than 115200 (i.e. 2.1% error) and that addressed the problem.
Which baudrate are you using here?
Johan
next prev parent reply other threads:[~2020-02-05 7:43 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-04 22:02 ch341 garbage read with 5.5.x kernel jakub nantl
2020-02-05 7:43 ` Johan Hovold [this message]
2020-02-05 7:53 ` jakub nantl
2020-02-05 8:50 ` Johan Hovold
2020-02-05 12:31 ` jakub nantl
2020-02-05 12:35 ` Johan Hovold
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