[PATCH] Input: st-keyscan - disable interrupt while clock is gated

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

The driver gates off its peripheral clock when the input device is not
open and during system suspend without wakeup. However, the interrupt is
requested without IRQF_NO_AUTOEN and remains unmasked when the device is
stopped. If a pending or spurious interrupt fires while the clock is
disabled, keyscan_isr() will attempt to read the matrix state register
with the clock gated off, triggering a bus fault (synchronous external
abort) and panicking the system.

Request the interrupt with IRQF_NO_AUTOEN, enable it in keyscan_start(),
and disable it in keyscan_stop() prior to gating the clock. Drop the
pointless clock enable/stop sequence in keyscan_probe(), leaving the
clock gated and hardware untouched until the device is opened.

Fixes: 062589b13991 ("Input: add st-keyscan driver")
Reported-by: sashiko-bot@kernel.org
Assisted-by: LLM
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
---
 drivers/input/keyboard/st-keyscan.c | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/drivers/input/keyboard/st-keyscan.c b/drivers/input/keyboard/st-keyscan.c
index ebeda020ffe1..6101bf53379a 100644
--- a/drivers/input/keyboard/st-keyscan.c
+++ b/drivers/input/keyboard/st-keyscan.c
@@ -75,6 +75,8 @@ static int keyscan_start(struct st_keyscan *keypad)
 
 	writel(KEYSCAN_CONFIG_ENABLE, keypad->base + KEYSCAN_CONFIG_OFF);
 
+	enable_irq(keypad->irq);
+
 	return 0;
 }
 
@@ -82,6 +84,8 @@ static void keyscan_stop(struct st_keyscan *keypad)
 {
 	writel(0, keypad->base + KEYSCAN_CONFIG_OFF);
 
+	disable_irq(keypad->irq);
+
 	clk_disable(keypad->clk);
 }
 
@@ -177,20 +181,12 @@ static int keyscan_probe(struct platform_device *pdev)
 		return dev_err_probe(&pdev->dev, PTR_ERR(keypad_data->clk),
 				     "cannot get clock\n");
 
-	error = clk_enable(keypad_data->clk);
-	if (error) {
-		dev_err(&pdev->dev, "failed to enable clock\n");
-		return error;
-	}
-
-	keyscan_stop(keypad_data);
-
 	keypad_data->irq = platform_get_irq(pdev, 0);
 	if (keypad_data->irq < 0)
 		return keypad_data->irq;
 
-	error = devm_request_irq(&pdev->dev, keypad_data->irq, keyscan_isr, 0,
-				 pdev->name, keypad_data);
+	error = devm_request_irq(&pdev->dev, keypad_data->irq, keyscan_isr,
+				 IRQF_NO_AUTOEN, pdev->name, keypad_data);
 	if (error)
 		return error;
 
-- 
2.55.0.897.gb25b4bd76c-goog


-- 
Dmitry