fix serial console suspend on PNP

Hi Greg,

The kernel command line parameter, no_console_suspend, enables the serial console to continue to output kernel message during system suspend/resume.

However, the PNP bus will disable and power-down pnp devices on system suspend, which defeats the purpose of no_console_suspend; namely to continue to output messages in case those are the last messages before crashing.

The first patch is a cleanup of the baroque logic of uart_suspend_port(). The second patch overrides the PNP bus disabling the console device if no_console_suspend is set. This patch uses existing PNP bus logic but perhaps in a way not originally intended.
The third patch requires Rafael's ack, as it adds a capability to allow the device to override the power-down function.
The fourth patch actually performs the power-down override enabled by patch 3.

With these patches, the PNP0501 device (16550A uart) will continue to output messages while system suspend finishes, as intended by the no_console_suspend parameter. [System resume is another problem, which I'm working on].

Regards,

Peter Hurley (4):
serial: core: Simplify console suspend logic in uart_suspend_port()
serial: 8250_pnp: Override pnp disable for no_console_suspend
PNP: Allow device to override ACPI device sleep
serial: 8250_pnp: Override pnp suspend for no_console_suspend

 drivers/pnp/driver.c               |  2 +-
 drivers/pnp/pnpacpi/core.c         |  2 +-
 drivers/tty/serial/8250/8250_pnp.c | 61 +++++++++++++++++++++++++++++++-------
 drivers/tty/serial/serial_core.c   | 35 +++++++++++-----------
 include/linux/pnp.h                |  3 ++
 5 files changed, 72 insertions(+), 31 deletions(-)

2.1.3