From a3cb39d258efef830181606134cfb0f7babe8c8e Mon Sep 17 00:00:00 2001 From: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Date: Mon, 17 Feb 2020 13:40:12 +0200 Subject: serial: core: Allow detach and attach serial device for console In the future we would like to disable power management on the serial devices used as kernel consoles to avoid weird behaviour in some cases. However, disabling PM may prevent system to go to deep sleep states, which in its turn leads to the higher power consumption. Tony Lindgren proposed a work around, i.e. allow user to detach such consoles to make PM working again. In case user wants to see what's going on, it also provides a mechanism to attach console back. Link: https://lists.openwall.net/linux-kernel/2018/09/29/65 Suggested-by: Tony Lindgren <tony@atomide.com> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://lore.kernel.org/r/20200217114016.49856-3-andriy.shevchenko@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- Documentation/ABI/testing/sysfs-tty | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'Documentation/ABI/testing/sysfs-tty') diff --git a/Documentation/ABI/testing/sysfs-tty b/Documentation/ABI/testing/sysfs-tty index 9eb3c2b6b040..e157130a6792 100644 --- a/Documentation/ABI/testing/sysfs-tty +++ b/Documentation/ABI/testing/sysfs-tty @@ -154,3 +154,10 @@ Description: device specification. For example, when user sets 7bytes on 16550A, which has 1/4/8/14 bytes trigger, the RX trigger is automatically changed to 4 bytes. + +What: /sys/class/tty/ttyS0/console +Date: February 2020 +Contact: Andy Shevchenko <andriy.shevchenko@linux.intel.com> +Description: + Allows user to detach or attach back the given device as + kernel console. It shows and accepts a boolean variable. -- cgit