USB: serial: ch341: fix lost character on LCR updates

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commit 8e83622ae7 upstream.

Disable LCR updates for pre-0x30 devices which use a different (unknown)
protocol for line control and where the current register write causes
the next received character to be lost.

Note that updating LCR using the INIT command has no effect on these
devices either.

Reported-by: Jonathan Woithe <jwoithe@just42.net>
Tested-by: Jonathan Woithe <jwoithe@just42.net>
Link: https://lore.kernel.org/r/Ys1iPTfiZRWj2gXs@marvin.atrad.com.au
Fixes: 4e46c410e0 ("USB: serial: ch341: reinitialize chip on reconfiguration")
Fixes: 55fa15b598 ("USB: serial: ch341: fix baud rate and line-control handling")
Cc: stable@vger.kernel.org      # 4.10
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

...

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Johan Hovold 2022-08-31 10:15:24 +02:00 • committed by Greg Kroah-Hartman

parent 735e7d0834

commit cffe34a4d0

1 changed files with 9 additions and 1 deletions

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drivers/usb/serial/ch341.c

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