netdev - [PATCH can v3 2/2] can: m_can: m_can_close(): stop clocks after device has been shut down

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Message-Id: <20240910-can-m_can-fix-ifup-v3-2-6c1720ba45ce@pengutronix.de>
Date: Tue, 10 Sep 2024 19:15:29 +0200
From: Marc Kleine-Budde <mkl@...gutronix.de>
To: Jake Hamby <Jake.Hamby@...edyne.com>, 
 Chandrasekar Ramakrishnan <rcsekar@...sung.com>, 
 Vincent Mailhol <mailhol.vincent@...adoo.fr>, 
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
 Dong Aisheng <b29396@...escale.com>, Varka Bhadram <varkabhadram@...il.com>
Cc: linux-can@...r.kernel.org, netdev@...r.kernel.org, 
 linux-kernel@...r.kernel.org, Marc Kleine-Budde <mkl@...gutronix.de>
Subject: [PATCH can v3 2/2] can: m_can: m_can_close(): stop clocks after
 device has been shut down

After calling m_can_stop() an interrupt may be pending or NAPI might
still be executed. This means the driver might still touch registers
of the IP core after the clocks have been disabled. This is not good
practice and might lead to aborts depending on the SoC integration.

To avoid these potential problems, make m_can_close() symmetric to
m_can_open(), i.e. stop the clocks at the end, right before shutting
down the transceiver.

Fixes: e0d1f4816f2a ("can: m_can: add Bosch M_CAN controller support")
Signed-off-by: Marc Kleine-Budde <mkl@...gutronix.de>
---
 drivers/net/can/m_can/m_can.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
index c1a07013433eb7b863eee072b959f46c1d5b008d..7fec04b024d5b83eece7a0b9c70a1352ee05138a 100644
--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c
@@ -1764,7 +1764,6 @@ static int m_can_close(struct net_device *dev)
 	netif_stop_queue(dev);

 	m_can_stop(dev);
-	m_can_clk_stop(cdev);
 	free_irq(dev->irq, dev);

 	m_can_clean(dev);
@@ -1779,6 +1778,7 @@ static int m_can_close(struct net_device *dev)

 	close_candev(dev);

+	m_can_clk_stop(cdev);
 	phy_power_off(cdev->transceiver);

 	return 0;

-- 
2.45.2