linux-kernel - [PATCH] media: v4l2-flash: Enter LED off state after file handle closed

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Message-ID: <0e7005f10222b57f100b442a8b48bb5bc2747e78.1767674614.git.cy_huang@richtek.com>
Date: Tue, 6 Jan 2026 13:32:59 +0800
From: <cy_huang@...htek.com>
To: Mauro Carvalho Chehab <mchehab@...nel.org>
CC: ChiYuan Huang <cy_huang@...htek.com>, <linux-media@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <stable@...r.kernel.org>, Roger Wang
	<roger-hy.wang@...iatek.com>
Subject: [PATCH] media: v4l2-flash: Enter LED off state after file handle closed

From: ChiYuan Huang <cy_huang@...htek.com>

To make sure LED enter off state after file handle is closed, initiatively
configure LED_MODE to NONE. This can guarantee whatever the previous state
is torch or strobe mode, the final state will be off.

Cc: stable@...r.kernel.org
Fixes : 42bd6f59ae90 ("media: Add registration helpers for V4L2 flash sub-devices")
Reported-by: Roger Wang <roger-hy.wang@...iatek.com>
Signed-off-by: ChiYuan Huang <cy_huang@...htek.com>
---
Hi,
  We encounter an issue. When the upper layer camera process is crashed,
if the new process did not reinit the LED,  it will keeps the previous
state whatever it's in torch or strobe mode

OS will handle the resource management. So when the process is crashed
or terminated, the 'close' API will be called to release resources.
That's why we add the initiative action to trigger LED off in file
handle close is called.
---
 drivers/media/v4l2-core/v4l2-flash-led-class.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/media/v4l2-core/v4l2-flash-led-class.c b/drivers/media/v4l2-core/v4l2-flash-led-class.c
index 355595a0fefa..347b37f3ef69 100644
--- a/drivers/media/v4l2-core/v4l2-flash-led-class.c
+++ b/drivers/media/v4l2-core/v4l2-flash-led-class.c
@@ -623,6 +623,12 @@ static int v4l2_flash_close(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh)
 		return 0;
 
 	if (led_cdev) {
+		/* If file handle is released, make sure LED enter off state */
+		ret = v4l2_ctrl_s_ctrl(v4l2_flash->ctrls[LED_MODE],
+			V4L2_FLASH_LED_MODE_NONE);
+		if (ret)
+			return ret;
+
 		mutex_lock(&led_cdev->led_access);
 
 		if (v4l2_flash->ctrls[STROBE_SOURCE])
-- 
2.34.1