PM: sleep: console: Fix the black screen issue

When the computer enters sleep status without a monitor
connected, the system switches the console to the virtual
terminal tty63(SUSPEND_CONSOLE).

If a monitor is subsequently connected before waking up,
the system skips the required VT restoration process
during wake-up, leaving the console on tty63 instead of
switching back to tty1.

To fix this issue, a global flag vt_switch_done is introduced
to record whether the system has successfully switched to
the suspend console via vt_move_to_console() during suspend.

If the switch was completed, vt_switch_done is set to 1.
Later during resume, this flag is checked to ensure that
the original console is restored properly by calling
vt_move_to_console(orig_fgconsole, 0).

This prevents scenarios where the resume logic skips console
restoration due to incorrect detection of the console state,
especially when a monitor is reconnected before waking up.

Signed-off-by: tuhaowen <tuhaowen@uniontech.com>
Link: https://patch.msgid.link/20250611032345.29962-1-tuhaowen@uniontech.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/kernel/power/console.c b/kernel/power/console.c
index fcdf0e14a47d478c4553de679eb68ad3c1871049..19c48aa5355d2bff37f5f5e23b279acfcb4aefc2 100644 (file)
--- a/kernel/power/console.c
+++ b/kernel/power/console.c
@@ -16,6 +16,7 @@
 #define SUSPEND_CONSOLE        (MAX_NR_CONSOLES-1)
 
 static int orig_fgconsole, orig_kmsg;
+static bool vt_switch_done;
 
 static DEFINE_MUTEX(vt_switch_mutex);
 
@@ -136,17 +137,21 @@ void pm_prepare_console(void)
        if (orig_fgconsole < 0)
                return;
 
+       vt_switch_done = true;
+
        orig_kmsg = vt_kmsg_redirect(SUSPEND_CONSOLE);
        return;
 }
 
 void pm_restore_console(void)
 {
-       if (!pm_vt_switch())
+       if (!pm_vt_switch() && !vt_switch_done)
                return;
 
        if (orig_fgconsole >= 0) {
                vt_move_to_console(orig_fgconsole, 0);
                vt_kmsg_redirect(orig_kmsg);
        }
+
+       vt_switch_done = false;
 }