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Date:   Mon, 22 Feb 2021 16:34:20 +0100
From:   Johan Hovold <johan@kernel.org>
To:     "Michael G. Katzmann" <michaelk@IEEE.org>
Cc:     charles-yeh@prolific.com.tw, linux-serial@vger.kernel.org,
        linux-usb@vger.kernel.org, Charles Yeh <charlesyeh522@gmail.com>,
        Joe Abbott <jabbott@rollanet.org>
Subject: Re: non-standard baud rates with Prolific 2303 USB-serial
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On Mon, Feb 22, 2021 at 09:53:39AM -0500, Michael G. Katzmann wrote:
> On 2/22/21 8:18 AM, Johan Hovold wrote:
> 
> I tried hardcoding buf[6-0] in pl2303_set_termios as
> 
> a8 a6 01 80 00 02 07 and got a bitrate of ~200kb 
> 
> so, no these settings do not work in my case (or I missunderstood your
> instructions 8-))

Thanks for testing (and that was with 0xa8 in byte 0, right?)

So it seems we have three devices with bcdDevice 0x0300 encoding the
divisors in slightly different ways and that are all still supported by
the vendor's Windows driver.

Unless Prolific are willing to shed some light on this, I guess someone
needs to try to figure out how the Windows driver determines which
encoding to use.

Is your device supposedly also a PL2303 TA? Could you post the output of
lsusb -v for completeness?

Johan