linux-kernel - [PATCH] leds: mt6360: Fix the second LED can not enable torch mode by V4L2

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Date: Tue, 9 Apr 2024 18:21:54 +0800
From: ChiaEn Wu <chiaen_wu@...htek.com>
To: <pavel@....cz>, <lee@...nel.org>, <matthias.bgg@...il.com>,
	<angelogioacchino.delregno@...labora.com>
CC: <linux-kernel@...r.kernel.org>, <linux-leds@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>, <linux-mediatek@...ts.infradead.org>,
	<peterwu.pub@...il.com>, <cy_huang@...htek.com>, ChiaEn Wu
	<chiaen_wu@...htek.com>
Subject: [PATCH] leds: mt6360: Fix the second LED can not enable torch mode by V4L2

V4L2 will disable strobe mode of the LED device when enable torch mode,
but this logic will conflict with the "priv->fled_torch_used"
in "mt6360_strobe_set()". So after enabling torch mode of the first
LED, the second LED will not be able to enable torch mode correctly.

Therefore, at the beginning of "mt6360_strobe_set()", check whether the
state of the upcoming change and the current LED device state are the
same, so as to avoid the above problem.

Signed-off-by: ChiaEn Wu <chiaen_wu@...htek.com>
---
 drivers/leds/flash/leds-mt6360.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/leds/flash/leds-mt6360.c b/drivers/leds/flash/leds-mt6360.c
index a90de82f4568..1b75b4d36834 100644
--- a/drivers/leds/flash/leds-mt6360.c
+++ b/drivers/leds/flash/leds-mt6360.c
@@ -241,10 +241,20 @@ static int mt6360_strobe_set(struct led_classdev_flash *fl_cdev, bool state)
 	u32 enable_mask = MT6360_STROBEN_MASK | MT6360_FLCSEN_MASK(led->led_no);
 	u32 val = state ? MT6360_FLCSEN_MASK(led->led_no) : 0;
 	u32 prev = priv->fled_strobe_used, curr;
-	int ret;
+	int ret = 0;
 
 	mutex_lock(&priv->lock);
 
+	/*
+	 * If the state of the upcoming change is the same as the current LED
+	 * device state, then skip the subsequent code to avoid conflict
+	 * with the flow of turning on LED torch mode in V4L2.
+	 */
+	if (state == !!(BIT(led->led_no) & prev)) {
+		dev_info(lcdev->dev, "No change in strobe state [0x%x]\n", prev);
+		goto unlock;
+	}
+
 	/*
 	 * Only one set of flash control logic, use the flag to avoid torch is
 	 * currently used
-- 
2.42.0