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Johan Hovold authored
While assumed not to make a difference, not using the factor-2 prescaler makes the receiver more susceptible to errors. Specifically, there have been reports of problems with devices that cannot generate a 115200 rate with a smaller error than 2.1% (e.g. 117647 bps). But this can also be reproduced with a low-speed RS232 tranceiver at 115200 when the input rate matches the nominal rate. So whenever possible, enable the factor-2 prescaler and halve the divisor in order to use settings closer to that of the previous algorithm. Fixes: 35714565 ("USB: serial: ch341: reimplement line-speed handling") Cc: stable <stable@vger.kernel.org> # 5.5 Reported-by:
Jakub Nantl <jn@forever.cz> Tested-by:
Jakub Nantl <jn@forever.cz> Reviewed-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by:
Johan Hovold <johan@kernel.org>
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