[PATCH 3.19.y-ckt 014/130] can: mcp251x: fix resume when device is down

From: Kamal Mostafa
Date: Thu Aug 27 2015 - 18:51:22 EST


3.19.8-ckt6 -stable review patch. If anyone has any objections, please let me know.

------------------

From: Stefan Agner <stefan@xxxxxxxx>

commit 25b401c1816ae64bcc5dcb1d39ab41812522a0ce upstream.

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@xxxxxxxx>
Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
---
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 c66d699..0c8094e 100644
--- a/drivers/net/can/spi/mcp251x.c
+++ b/drivers/net/can/spi/mcp251x.c
@@ -1220,17 +1220,16 @@ 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;
--
1.9.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/