netdev - [PATCH 1/2] can: mcp251x: fix resume when device is down

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Message-Id: <1431966808-26213-1-git-send-email-stefan@agner.ch>
Date:	Mon, 18 May 2015 18:33:27 +0200
From:	Stefan Agner <stefan@...er.ch>
To:	wg@...ndegger.com, mkl@...gutronix.de
Cc:	chripell@...e.org, linux-can@...r.kernel.org,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	stefan@...er.ch
Subject: [PATCH 1/2] can: mcp251x: fix resume when device is down

If a valid power regulator or a dummy regulator is used (which
happens to be the case when no regulator is specified), restart_work
is queued no matter whether the device was running or not at suspend
time. Since work queues get initialized in the ndo_open callback,
resuming leads to a NULL pointer exception.

Reverse exactly the steps executed at suspend time:
- Enable the power regulator in any case
- Enable the transceiver regulator if the device was running, even in
  case we have a power regulator
- Queue restart_work only in case the device was running

Fixes: bf66f3736a94 ("can: mcp251x: Move to threaded interrupts instead of workqueues.")
Signed-off-by: Stefan Agner <stefan@...er.ch>
---
 drivers/net/can/spi/mcp251x.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/drivers/net/can/spi/mcp251x.c b/drivers/net/can/spi/mcp251x.c
index bf63fee..34c625e 100644
--- a/drivers/net/can/spi/mcp251x.c
+++ b/drivers/net/can/spi/mcp251x.c
@@ -1221,17 +1221,16 @@ static int __maybe_unused mcp251x_can_resume(struct device *dev)
 	struct spi_device *spi = to_spi_device(dev);
 	struct mcp251x_priv *priv = spi_get_drvdata(spi);
 
-	if (priv->after_suspend & AFTER_SUSPEND_POWER) {
+	if (priv->after_suspend & AFTER_SUSPEND_POWER)
 		mcp251x_power_enable(priv->power, 1);
+
+	if (priv->after_suspend & AFTER_SUSPEND_UP) {
+		mcp251x_power_enable(priv->transceiver, 1);
 		queue_work(priv->wq, &priv->restart_work);
 	} else {
-		if (priv->after_suspend & AFTER_SUSPEND_UP) {
-			mcp251x_power_enable(priv->transceiver, 1);
-			queue_work(priv->wq, &priv->restart_work);
-		} else {
-			priv->after_suspend = 0;
-		}
+		priv->after_suspend = 0;
 	}
+
 	priv->force_quit = 0;
 	enable_irq(spi->irq);
 	return 0;
-- 
2.4.1

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