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Date:   Mon, 28 Nov 2022 15:41:59 +0100
From:   Johan Hovold <johan@kernel.org>
To:     Alex Henrie <alexh@vpitech.com>
Cc:     linux-usb@vger.kernel.org, johanna.abrahamsson@afconsult.com,
        alexhenrie24@gmail.com
Subject: Re: [PATCH] USB: serial: cp210x: map B0 to B9600
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On Fri, Nov 25, 2022 at 08:58:25PM -0700, Alex Henrie wrote:
> When a baud rate of 0 is requested, both the 8250 driver and the FTDI
> driver reset the baud rate to the default of 9600 (see the comment above
> the uart_get_baud_rate function). Some old versions of the NXP blhost
> utility depend on this behavior. 

What exactly do you mean by "depend on" here? Setting B0 is supposed to
hang up a modem connection by deasserting the modem control lines, but
there's nothing mandating any particular line speed to be set in
hardware. Why would that even matter?

If the user space tool is thrown off by the fact that B0 isn't
implemented, perhaps that's what should be addressed.

Johan