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| author | Peter Hurley <peter@hurleysoftware.com> | 2015-03-09 14:05:01 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-05-06 22:03:59 +0200 |
| commit | cc1064fc8f1d71f9c3429e6bdd8129629fc39784 (patch) | |
| tree | 4ce26978eabee5d767cd5c1e816af6e6b9e7cbda /drivers/tty | |
| parent | 8067aec1b07ce3f80c8209eb3589abdf38753ac1 (diff) | |
| download | lwn-cc1064fc8f1d71f9c3429e6bdd8129629fc39784.tar.gz lwn-cc1064fc8f1d71f9c3429e6bdd8129629fc39784.zip | |
serial: 8250: Check UART_SCR is writable
commit f01a0bd8921b9d6668d41fae3198970e6318f532 upstream.
Au1x00/RT2800+ doesn't implement the 8250 scratch register (and
this may be true of other h/w currently supported by the 8250 driver);
read back the canary value written to the scratch register to enable
the console h/w restart after resume from system suspend.
Fixes: 4516d50aabedb ("serial: 8250: Use canary to restart console ...")
Reported-by: Mason <slash.tmp@free.fr>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty')
| -rw-r--r-- | drivers/tty/serial/8250/8250_core.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c index deae122c9c4b..d465ace95186 100644 --- a/drivers/tty/serial/8250/8250_core.c +++ b/drivers/tty/serial/8250/8250_core.c @@ -3444,7 +3444,8 @@ void serial8250_suspend_port(int line) port->type != PORT_8250) { unsigned char canary = 0xa5; serial_out(up, UART_SCR, canary); - up->canary = canary; + if (serial_in(up, UART_SCR) == canary) + up->canary = canary; } uart_suspend_port(&serial8250_reg, port); |