[PATCH] PM/console: Fix the black screen issue

[tuhaowen <tuhaowen@uniontech.com>]

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.

Signed-off-by: tuhaowen <tuhaowen@uniontech.com>
---
 kernel/power/console.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/kernel/power/console.c b/kernel/power/console.c
index fcdf0e14a47d..832e04bf5439 100644
--- 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 int vt_switch_done;
 
 static DEFINE_MUTEX(vt_switch_mutex);
 
@@ -136,15 +137,19 @@ void pm_prepare_console(void)
 	if (orig_fgconsole < 0)
 		return;
 
+	vt_switch_done = 1;
+
 	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;
 
+	vt_switch_done = 0;
+
 	if (orig_fgconsole >= 0) {
 		vt_move_to_console(orig_fgconsole, 0);
 		vt_kmsg_redirect(orig_kmsg);
-- 
2.20.1