Thread (651 messages) 651 messages, 7 authors, 2025-08-28
STALE294d

[PATCH 5.15 316/644] PM: sleep: console: Fix the black screen issue

From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: 2025-08-26 13:49:44
Also in: linux-patches
Subsystem: hibernation (aka software suspend, aka swsusp), suspend to ram, the rest · Maintainers: "Rafael J. Wysocki", Linus Torvalds

5.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: tuhaowen <redacted>

[ Upstream commit 4266e8fa56d3d982bf451d382a410b9db432015c ]

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 <redacted>
Link: https://patch.msgid.link/20250611032345.29962-1-tuhaowen@uniontech.com
Signed-off-by: Rafael J. Wysocki <redacted>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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..19c48aa5355d 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 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;
 }
-- 
2.39.5


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