linux-kernel - [PATCH v2] gpio: rockchip: resolve underflow issue

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Message-Id: <20240823034314.62305-5-ye.zhang@rock-chips.com>
Date: Fri, 23 Aug 2024 11:43:07 +0800
From: Ye Zhang <ye.zhang@...k-chips.com>
To: linus.walleij@...aro.org,
	brgl@...ev.pl,
	heiko@...ech.de,
	linux-gpio@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org
Cc: linux-rockchip@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	mika.westerberg@...ux.intel.com,
	andriy.shevchenko@...ux.intel.com,
	tao.huang@...k-chips.com,
	finley.xiao@...k-chips.com,
	tim.chen@...k-chips.com,
	elaine.zhang@...k-chips.com,
	Ye Zhang <ye.zhang@...k-chips.com>
Subject: [PATCH v2] gpio: rockchip: resolve underflow issue

div_reg may be < 0 if debounce is zero, causing the unsigned int to
overflow.

Fixes: 3bcbd1a85b68 ("gpio/rockchip: support next version gpio controller")
Signed-off-by: Ye Zhang <ye.zhang@...k-chips.com>
---
 drivers/gpio/gpio-rockchip.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/gpio/gpio-rockchip.c b/drivers/gpio/gpio-rockchip.c
index bf22b103b6a2..c3a87d075908 100644
--- a/drivers/gpio/gpio-rockchip.c
+++ b/drivers/gpio/gpio-rockchip.c
@@ -204,8 +204,8 @@ static int rockchip_gpio_set_debounce(struct gpio_chip *gc,
 	unsigned int cur_div_reg;
 	u64 div;
 
-	if (bank->gpio_type == GPIO_TYPE_V2 && !IS_ERR(bank->db_clk)) {
-		div_debounce_support = true;
+	div_debounce_support = (bank->gpio_type == GPIO_TYPE_V2) && !IS_ERR(bank->db_clk);
+	if (debounce && div_debounce_support) {
 		freq = clk_get_rate(bank->db_clk);
 		if (!freq)
 			return -EINVAL;
@@ -216,8 +216,6 @@ static int rockchip_gpio_set_debounce(struct gpio_chip *gc,
 
 		div = (u64)debounce * freq;
 		div_reg = DIV_ROUND_CLOSEST_ULL(div, 2 * USEC_PER_SEC) - 1;
-	} else {
-		div_debounce_support = false;
 	}
 
 	raw_spin_lock_irqsave(&bank->slock, flags);
-- 
2.34.1