can: mcp251x: fix resume when device is down

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@agner.ch>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
[lizf: Backported to 3.4:
 - adjust filename
 - adjust context]
Signed-off-by: Zefan Li <lizefan@huawei.com>

diff --git a/drivers/net/can/mcp251x.c b/drivers/net/can/mcp251x.c
index 9d6074273caa54b576eedb620e9c117c7dd3a2cd..d07426d007d05d5646e1c68ccd31972ec0af2e8b 100644 (file)
--- a/drivers/net/can/mcp251x.c
+++ b/drivers/net/can/mcp251x.c
@@ -1161,18 +1161,17 @@ static int mcp251x_can_resume(struct spi_device *spi)
        struct mcp251x_platform_data *pdata = spi->dev.platform_data;
        struct mcp251x_priv *priv = dev_get_drvdata(&spi->dev);
 
-       if (priv->after_suspend & AFTER_SUSPEND_POWER) {
+       if (priv->after_suspend & AFTER_SUSPEND_POWER)
                pdata->power_enable(1);
+
+       if (priv->after_suspend & AFTER_SUSPEND_UP) {
+               if (pdata->transceiver_enable)
+                       pdata->transceiver_enable(1);
                queue_work(priv->wq, &priv->restart_work);
        } else {
-               if (priv->after_suspend & AFTER_SUSPEND_UP) {
-                       if (pdata->transceiver_enable)
-                               pdata->transceiver_enable(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;