target/linux/ar7/patches-4.9/002-MIPS-AR7-ensure-the-port-type-s-FCR-value-is-used.patch

   1 From ee6c9d41de084b2cefd90e5e0c9f30a35f6d3967 Mon Sep 17 00:00:00 2001
   2 From: Jonas Gorski <jonas.gorski@gmail.com>
   3 Date: Sun, 29 Oct 2017 15:50:42 +0100
   4 Subject: [PATCH RFC 3/3] MIPS: AR7: ensure the port type's FCR value is used
   5
   6 Since commit aef9a7bd9b67 ("serial/uart/8250: Add tunable RX interrupt
   7 trigger I/F of FIFO buffers"), the port's default FCR value isn't used
   8 in serial8250_do_set_termios anymore, but copied over once in
   9 serial8250_config_port and then modified as needed.
  10
  11 Unfortunately, serial8250_config_port will never be called if the port
  12 is shared between kernel and userspace, and the port's flag doesn't have
  13 UPF_BOOT_AUTOCONF, which would trigger a serial8250_config_port as well.
  14
  15 This causes garbled output from userspace:
  16
  17 [    5.220000] random: procd urandom read with 49 bits of entropy available
  18 ers
  19    [kee
  20
  21 Fix this by forcing it to be configured on boot, resulting in the
  22 expected output:
  23
  24 [    5.250000] random: procd urandom read with 50 bits of entropy available
  25 Press the [f] key and hit [enter] to enter failsafe mode
  26 Press the [1], [2], [3] or [4] key and hit [enter] to select the debug level
  27
  28 Fixes: aef9a7bd9b67 ("serial/uart/8250: Add tunable RX interrupt trigger I/F of FIFO buffers")
  29 Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com>
  30 ---
  31 I'm not sure if this is just AR7's issue, or if this points to a general
  32 issue for UARTs used as kernel console and login console with the "fixed"
  33 commit.
  34
  35  arch/mips/ar7/platform.c | 2 +-
  36  1 file changed, 1 insertion(+), 1 deletion(-)
  37
  38 --- a/arch/mips/ar7/platform.c
  39 +++ b/arch/mips/ar7/platform.c
  40 @@ -576,7 +576,7 @@ static int __init ar7_register_uarts(voi
  41         uart_port.type          = PORT_AR7;
  42         uart_port.uartclk       = clk_get_rate(bus_clk) / 2;
  43         uart_port.iotype        = UPIO_MEM32;
  44 -       uart_port.flags         = UPF_FIXED_TYPE;
  45 +       uart_port.flags         = UPF_FIXED_TYPE | UPF_BOOT_AUTOCONF;
  46         uart_port.regshift      = 2;
  47
  48         uart_port.line          = 0;