Re: [PATCH] USB: serial: ch341: fix receiver regression

[Johan Hovold <johan@kernel.org>]

On Thu, Feb 06, 2020 at 11:45:46AM +0000, Greg Kroah-Hartman wrote:
> On Thu, Feb 06, 2020 at 12:18:19PM +0100, Johan Hovold wrote:
> > 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 is close to nominal.
> > 
> > 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: 35714565089e ("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>
> > Signed-off-by: Johan Hovold <johan@kernel.org>
> 
> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Thanks for reviewing. Now applied.

Johan