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   1 From dominique.martinet@atmark-techno.com  Thu Jan 12 13:46:08 2023
   2 From: Dominique Martinet <dominique.martinet@atmark-techno.com>
   3 Date: Fri, 23 Dec 2022 13:23:54 +0900
   4 Subject: serial: fixup backport of "serial: Deassert Transmit Enable on probe in driver-specific way"
   5 To: "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>, "Jiri Slaby" <jirislaby@kernel.org>, "Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>, "Lukas Wunner" <lukas@wunner.de>, "Rasmus Villemoes" <linux@rasmusvillemoes.dk>
   6 Cc: Daisuke Mizobuchi <mizo@atmark-techno.com>, stable@vger.kernel.org, linux-serial@vger.kernel.org, Dominique Martinet <dominique.martinet@atmark-techno.com>
   7 Message-ID: <20221223042354.4080724-2-dominique.martinet@atmark-techno.com>
   8
   9 From: Rasmus Villemoes <linux@rasmusvillemoes.dk>
  10
  11 When 7c7f9bc986e6 ("serial: Deassert Transmit Enable on probe in
  12 driver-specific way") got backported to 5.10.y, there known as
  13 26a2b9c468de, some hunks were accidentally left out.
  14
  15 In serial_core.c, it is possible that the omission in
  16 uart_suspend_port() is harmless, but the backport did have the
  17 corresponding hunk in uart_resume_port(), it runs counter to the
  18 original commit's intention of
  19
  20   Skip any invocation of ->set_mctrl() if RS485 is enabled.
  21
  22 and it's certainly better to be aligned with upstream.
  23
  24 Link: https://lkml.kernel.org/r/20221222114414.1886632-1-linux@rasmusvillemoes.dk
  25 Fixes: 26a2b9c468de ("serial: Deassert Transmit Enable on probe in driver-specific way")
  26 Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
  27 [the fsl_lpuart part of the 5.15 patch is not required on 5.10,
  28 because the code before 26a2b9c468de was incorrectly not calling
  29 uart_remove_one_port on failed_get_rs485]
  30 Signed-off-by: Dominique Martinet <dominique.martinet@atmark-techno.com>
  31 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  32 ---
  33  drivers/tty/serial/serial_core.c |    3 ++-
  34  1 file changed, 2 insertions(+), 1 deletion(-)
  35
  36 --- a/drivers/tty/serial/serial_core.c
  37 +++ b/drivers/tty/serial/serial_core.c
  38 @@ -2254,7 +2254,8 @@ int uart_suspend_port(struct uart_driver
  39
  40                 spin_lock_irq(&uport->lock);
  41                 ops->stop_tx(uport);
  42 -               ops->set_mctrl(uport, 0);
  43 +               if (!(uport->rs485.flags & SER_RS485_ENABLED))
  44 +                       ops->set_mctrl(uport, 0);
  45                 ops->stop_rx(uport);
  46                 spin_unlock_irq(&uport->lock);
  47