netdev - [PATCH net v3] net: dsa: qca8k: fix illegal usage of GPIO

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Message-Id: <1706266175-3408-1-git-send-email-michal.vokac@ysoft.com>
Date: Fri, 26 Jan 2024 11:49:35 +0100
From: Michal Vokáč <michal.vokac@...ft.com>
To: Andrew Lunn <andrew@...n.ch>,
	Florian Fainelli <f.fainelli@...il.com>,
	Vladimir Oltean <olteanv@...il.com>,
	"David S. Miller" <davem@...emloft.net>
Cc: Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Christian Marangi <ansuelsmth@...il.com>,
	"Russell King (Oracle)" <rmk+kernel@...linux.org.uk>,
	Marek Behún <kabel@...nel.org>,
	Christian Lamparter <chunkeey@...il.com>,
	netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	petr.benes@...ft.com,
	Michal Vokáč <michal.vokac@...ft.com>
Subject: [PATCH net v3] net: dsa: qca8k: fix illegal usage of GPIO

When working with GPIO, its direction must be set either when the GPIO is
requested by gpiod_get*() or later on by one of the gpiod_direction_*()
functions. Neither of this is done here which results in undefined
behavior on some systems.

As the reset GPIO is used right after it is requested here, it makes sense
to configure it as GPIOD_OUT_HIGH right away. With that, the following
gpiod_set_value_cansleep(1) becomes redundant and can be safely
removed.

Fixes: a653f2f538f9 ("net: dsa: qca8k: introduce reset via gpio feature")
Signed-off-by: Michal Vokáč <michal.vokac@...ft.com>
---
Changes in v3:
- Keep line length under 80 characters for netdev changes

Changes in v2:
- Remove the now redundant gpiod_set_value_cansleep(1) call.

 drivers/net/dsa/qca/qca8k-8xxx.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/net/dsa/qca/qca8k-8xxx.c b/drivers/net/dsa/qca/qca8k-8xxx.c
index ec57d9d52072..c247ab09874c 100644
--- a/drivers/net/dsa/qca/qca8k-8xxx.c
+++ b/drivers/net/dsa/qca/qca8k-8xxx.c
@@ -2038,12 +2038,11 @@ qca8k_sw_probe(struct mdio_device *mdiodev)
 	priv->info = of_device_get_match_data(priv->dev);
 
 	priv->reset_gpio = devm_gpiod_get_optional(priv->dev, "reset",
-						   GPIOD_ASIS);
+						   GPIOD_OUT_HIGH);
 	if (IS_ERR(priv->reset_gpio))
 		return PTR_ERR(priv->reset_gpio);
 
 	if (priv->reset_gpio) {
-		gpiod_set_value_cansleep(priv->reset_gpio, 1);
 		/* The active low duration must be greater than 10 ms
 		 * and checkpatch.pl wants 20 ms.
 		 */
-- 
2.1.4