linux-kernel - [PATCH] leds: mt6323: move period calculation

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Message-Id: <20200809163221.32413-1-trix@redhat.com>
Date:   Sun,  9 Aug 2020 09:32:21 -0700
From:   trix@...hat.com
To:     sean.wang@...iatek.com, pavel@....cz, dmurphy@...com,
        matthias.bgg@...il.com, jacek.anaszewski@...il.com
Cc:     linux-leds@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Tom Rix <trix@...hat.com>
Subject: [PATCH] leds: mt6323: move period calculation

From: Tom Rix <trix@...hat.com>

clang static analysis reports this problem

leds-mt6323.c:275:12: warning: Division by zero
        duty_hw = MT6323_CAL_HW_DUTY(*delay_on, period);
                  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This is because period can be 0.

	period = *delay_on + *delay_off;

There is a later check that *delay_on/off are valid.

	if (!*delay_on && !*delay_off) {
		*delay_on = 500;
		*delay_off = 500;
	}

Setting the delay_on/off means period needs to be recalculated
anyway.  So move the period statements after this check.

Fixes: 216ec6cc4c19 ("leds: Add LED support for MT6323 PMIC")

Signed-off-by: Tom Rix <trix@...hat.com>
---
 drivers/leds/leds-mt6323.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/leds/leds-mt6323.c b/drivers/leds/leds-mt6323.c
index 2a13e3161bf4..7b240771e45b 100644
--- a/drivers/leds/leds-mt6323.c
+++ b/drivers/leds/leds-mt6323.c
@@ -248,15 +248,6 @@ static int mt6323_led_set_blink(struct led_classdev *cdev,
 	u8 duty_hw;
 	int ret;
 
-	/*
-	 * Units are in ms, if over the hardware able
-	 * to support, fallback into software blink
-	 */
-	period = *delay_on + *delay_off;
-
-	if (period > MT6323_MAX_PERIOD)
-		return -EINVAL;
-
 	/*
 	 * LED subsystem requires a default user
 	 * friendly blink pattern for the LED so using
@@ -268,6 +259,15 @@ static int mt6323_led_set_blink(struct led_classdev *cdev,
 		*delay_off = 500;
 	}
 
+	/*
+	 * Units are in ms, if over the hardware able
+	 * to support, fallback into software blink
+	 */
+	period = *delay_on + *delay_off;
+
+	if (period > MT6323_MAX_PERIOD)
+		return -EINVAL;
+
 	/*
 	 * Calculate duty_hw based on the percentage of period during
 	 * which the led is ON.
-- 
2.18.1