linux-kernel - [PATCH v7] tty: Fix the keyboard led light display problem

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Date:   Tue, 26 Oct 2021 10:40:32 +0800
From:   lianzhi chang <changlianzhi@...ontech.com>
To:     linux-kernel@...r.kernel.org
Cc:     dmitry.torokhov@...il.com, gregkh@...uxfoundation.org,
        jirislaby@...nel.org, andriy.shevchenko@...ux.intel.com,
        282827961@...com, lianzhi chang <changlianzhi@...ontech.com>
Subject: [PATCH v7] tty: Fix the keyboard led light display problem

Switching from the desktop environment to the tty environment,
the state of the keyboard led lights and the state of the keyboard
lock are inconsistent. This is because the attribute kb->kbdmode
of the tty bound in the desktop environment (xorg) is set to
VC_OFF, which causes the ledstate and kb->ledflagstate
values of the bound tty to always be 0, which causes the switch
from the desktop When to the tty environment, the LED light
status is inconsistent with the keyboard lock status.

Signed-off-by: lianzhi chang <changlianzhi@...ontech.com>
---
 v6-->v7:
 Delete the casting in the kbd_update_ledstate function, and the
 new code no longer needs casting.
 
 drivers/tty/vt/keyboard.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/drivers/tty/vt/keyboard.c b/drivers/tty/vt/keyboard.c
index c7fbbcdcc346..e2cf40d06483 100644
--- a/drivers/tty/vt/keyboard.c
+++ b/drivers/tty/vt/keyboard.c
@@ -1130,6 +1130,19 @@ static void kbd_init_leds(void)
 
 #endif
 
+static void kbd_update_ledstate(struct input_dev *dev)
+{
+	if (!!test_bit(LED_NUML, dev->led) !=
+	    !!(ledstate & BIT(VC_NUMLOCK)))
+		ledstate ^= BIT(VC_NUMLOCK);
+	if (!!test_bit(LED_CAPSL, dev->led) !=
+	    !!(ledstate & BIT(VC_CAPSLOCK)))
+		ledstate ^= BIT(VC_CAPSLOCK);
+	if (!!test_bit(LED_SCROLLL, dev->led) !=
+	    !!(ledstate & BIT(VC_SCROLLOCK)))
+		ledstate ^= BIT(VC_SCROLLOCK);
+}
+
 /*
  * The leds display either (i) the status of NumLock, CapsLock, ScrollLock,
  * or (ii) whatever pattern of lights people want to show using KDSETLED,
@@ -1247,9 +1260,14 @@ void vt_kbd_con_stop(unsigned int console)
  */
 static void kbd_bh(struct tasklet_struct *unused)
 {
+	struct kbd_struct *kb;
 	unsigned int leds;
 	unsigned long flags;
 
+	kb = kbd_table + fg_console;
+	if (kb->kbdmode == VC_OFF)
+		return;
+
 	spin_lock_irqsave(&led_lock, flags);
 	leds = getleds();
 	leds |= (unsigned int)kbd->lockstate << 8;
@@ -1524,6 +1542,9 @@ static void kbd_event(struct input_handle *handle, unsigned int event_type,
 	/* We are called with interrupts disabled, just take the lock */
 	spin_lock(&kbd_event_lock);
 
+	if (test_bit(EV_LED, handle->dev->evbit))
+		kbd_update_ledstate(handle->dev);
+
 	if (event_type == EV_MSC && event_code == MSC_RAW &&
 			kbd_is_hw_raw(handle->dev))
 		kbd_rawcode(value);
-- 
2.20.1