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Date:   Fri, 8 Jan 2021 15:32:48 +0100
From:   Johan Hovold <johan@kernel.org>
To:     Joe Abbott <jabbott@rollanet.org>
Cc:     Johan Hovold <johan@kernel.org>, linux-usb@vger.kernel.org
Subject: Re: pl2303.c 110 baud not working
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Please keep the USB list on CC.

On Fri, Jan 08, 2021 at 08:02:36AM -0600, Joe Abbott wrote:
> Thanks for the reply.
> 
> kernel version is 5.0.0-32-generic.  I've restored pl2303.ko to original.

5.0 should work as well.

> Chip version is PL2303TA.

And I believe that one is supposed to be compatible with HXD.

> When I loopback rs232 to pc at 150 baud it looks normal.  After
> setting to 110 baud it returns at a much higher rate and scope trace looks
> the same as when set to 9600 baud.
>
> Setting up debug might be beyond my abilities unless I could find a good
> how-to that I could follow.

You can either use debugfs:

	echo module pl2303 +p > /sys/kernel/debug/dynamic_debug/control

or provide an argument to modprobe:

	modprobe pl2303 dyndbg==p

Then just check demsg after calling stty (110 evenp).

> I'll look into capturing some windows packets at 110 and 9600.

Sounds good.

Johan