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   1 From linux@rasmusvillemoes.dk  Thu Jan 12 13:40:41 2023
   2 From: Rasmus Villemoes <linux@rasmusvillemoes.dk>
   3 Date: Thu, 22 Dec 2022 12:44:14 +0100
   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>, "Lukas Wunner" <lukas@wunner.de>, "Dominique Martinet" <dominique.martinet@atmark-techno.com>, "Daisuke Mizobuchi" <mizo@atmark-techno.com>, "Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>
   6 Cc: linux-serial@vger.kernel.org, stable@vger.kernel.org, Rasmus Villemoes <linux@rasmusvillemoes.dk>
   7 Message-ID: <20221222114414.1886632-1-linux@rasmusvillemoes.dk>
   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 5.15.y, there known as
  13 b079d3775237, some hunks were accidentally left out.
  14
  15 In fsl_lpuart.c, this amounts to uart_remove_one_port() being called
  16 in an error path despite uart_add_one_port() not having been called.
  17
  18 In serial_core.c, it is possible that the omission in
  19 uart_suspend_port() is harmless, but the backport did have the
  20 corresponding hunk in uart_resume_port(), it runs counter to the
  21 original commit's intention of
  22
  23   Skip any invocation of ->set_mctrl() if RS485 is enabled.
  24
  25 and it's certainly better to be aligned with upstream.
  26
  27 Fixes: b079d3775237 ("serial: Deassert Transmit Enable on probe in driver-specific way")
  28 Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
  29 Reviewed-by: Dominique MARTINET <dominique.martinet@atmark-techno.com>
  30 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  31 ---
  32  drivers/tty/serial/fsl_lpuart.c  |    2 +-
  33  drivers/tty/serial/serial_core.c |    3 ++-
  34  2 files changed, 3 insertions(+), 2 deletions(-)
  35
  36 --- a/drivers/tty/serial/fsl_lpuart.c
  37 +++ b/drivers/tty/serial/fsl_lpuart.c
  38 @@ -2784,9 +2784,9 @@ static int lpuart_probe(struct platform_
  39         return 0;
  40
  41  failed_irq_request:
  42 -failed_get_rs485:
  43         uart_remove_one_port(&lpuart_reg, &sport->port);
  44  failed_attach_port:
  45 +failed_get_rs485:
  46  failed_reset:
  47         lpuart_disable_clks(sport);
  48         return ret;
  49 --- a/drivers/tty/serial/serial_core.c
  50 +++ b/drivers/tty/serial/serial_core.c
  51 @@ -2225,7 +2225,8 @@ int uart_suspend_port(struct uart_driver
  52
  53                 spin_lock_irq(&uport->lock);
  54                 ops->stop_tx(uport);
  55 -               ops->set_mctrl(uport, 0);
  56 +               if (!(uport->rs485.flags & SER_RS485_ENABLED))
  57 +                       ops->set_mctrl(uport, 0);
  58                 ops->stop_rx(uport);
  59                 spin_unlock_irq(&uport->lock);
  60