target/linux/generic/backport-4.14/180-earlycon-initialize-port-uartclk-based-on-clock-frequency-property.patch

   1 From 814453adea7d081ad8917aa0f32d6a14165a3563 Mon Sep 17 00:00:00 2001
   2 From: Michal Simek <michal.simek@xilinx.com>
   3 Date: Tue, 10 Apr 2018 15:32:28 +0200
   4 Subject: earlycon: Initialize port->uartclk based on clock-frequency property
   5
   6 From: Michal Simek <michal.simek@xilinx.com>
   7
   8 commit 814453adea7d081ad8917aa0f32d6a14165a3563 upstream.
   9
  10 On DT based platforms when current-speed property is present baudrate
  11 is setup. Also port->uartclk is initialized to bogus BASE_BAUD * 16
  12 value. Drivers like uartps/ns16550 contain logic when baudrate and
  13 uartclk is used for baudrate calculation.
  14
  15 The patch is reading optional clock-frequency property to replace bogus
  16 BASE_BAUD * 16 calculation to have proper baudrate calculation.
  17
  18 [-stable comment: commit 31cb9a8575ca ("earlycon: initialise baud field
  19  of earlycon device structure") has changed 8250_early.c behavior which
  20  now tries to setup UART speed. Ignoring clock-frequency results in
  21  wrong value of calculated divisor & malformed early console output.]
  22
  23 Fixes: 31cb9a8575ca ("earlycon: initialise baud field of earlycon device structure")
  24 Signed-off-by: Michal Simek <michal.simek@xilinx.com>
  25 [rmilecki: add -stable comment and Fixes tag]
  26 Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
  27 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  28
  29 ---
  30  drivers/tty/serial/earlycon.c |    4 ++++
  31  1 file changed, 4 insertions(+)
  32
  33 --- a/drivers/tty/serial/earlycon.c
  34 +++ b/drivers/tty/serial/earlycon.c
  35 @@ -289,6 +289,10 @@ int __init of_setup_earlycon(const struc
  36         if (val)
  37                 early_console_dev.baud = be32_to_cpu(*val);
  38
  39 +       val = of_get_flat_dt_prop(node, "clock-frequency", NULL);
  40 +       if (val)
  41 +               port->uartclk = be32_to_cpu(*val);
  42 +
  43         if (options) {
  44                 early_console_dev.baud = simple_strtoul(options, NULL, 0);
  45                 strlcpy(early_console_dev.options, options,