Re: [PATCH] Input: matrix_keypad - fix keypad does not response

At 2018-02-03 21:44:50, "Marcus Folkesson" [off-list ref] wrote:

quoted

diff --git a/drivers/input/keyboard/matrix_keypad.c b/drivers/input/keyboard/matrix_keypad.c
index 1f316d66e6f7..13fe51824637 100644
--- a/drivers/input/keyboard/matrix_keypad.c
+++ b/drivers/input/keyboard/matrix_keypad.c

@@ -169,7 +169,8 @@ static void matrix_keypad_scan(struct work_struct *work)
 	/* Enable IRQs again */
 	spin_lock_irq(&keypad->lock);
 	keypad->scan_pending = false;
-	enable_row_irqs(keypad);
+	if (keypad->stopped == false)
+		enable_row_irqs(keypad);
 	spin_unlock_irq(&keypad->lock);
 }
 

@@ -202,14 +203,16 @@ static int matrix_keypad_start(struct input_dev *dev)
 {
 	struct matrix_keypad *keypad = input_get_drvdata(dev);
 
+	spin_lock_irq(&keypad->lock);
 	keypad->stopped = false;
-	mb();
 
 	/*
 	 * Schedule an immediate key scan to capture current key state;
 	 * columns will be activated and IRQs be enabled after the scan.
 	 */
-	schedule_delayed_work(&keypad->work, 0);
+	if (keypad->scan_pending == false)
+		schedule_delayed_work(&keypad->work, 0);
+	spin_unlock_irq(&keypad->lock);
 
 	return 0;
 }

@@ -218,14 +221,17 @@ static void matrix_keypad_stop(struct input_dev *dev)
 {
 	struct matrix_keypad *keypad = input_get_drvdata(dev);
 
+	spin_lock_irq(&keypad->lock);
 	keypad->stopped = true;
-	mb();
-	flush_work(&keypad->work.work);
 	/*
 	 * matrix_keypad_scan() will leave IRQs enabled;
 	 * we should disable them now.
 	 */
-	disable_row_irqs(keypad);
+	if (keypad->scan_pending == false)
+		disable_row_irqs(keypad);
+	spin_unlock_irq(&keypad->lock);
+
+	flush_work(&keypad->work.work);
 }

Hum, I think we should use spin_lock_irqsave/spin_lock_irqrestore
instead to be on the safe side. 
I don't see how we could guarantee that irqs is allways enabled when
calling spin_lock_irq().

spin_lock_irq and  spin_unlock_irq are called in matrix_keypad_stop and matrix_keypad_start
which are in suspend and resume,  they run in process context, matrix_keypad_scan runs in
worker which is in process context also.