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

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

[Stefan Agner]

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>
---
 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

[PATCH 2/2] can: mcp251x: get regulators optionally

[Stefan Agner]

The regulators power and transceiver are optional. If those are not
present, the pointer (or error pointer) is correctly handled by the
driver, hence we can use devm_regulator_get_optional safely, which
avoids regulators getting created.

Signed-off-by: Stefan Agner <stefan@agner.ch>
---
 drivers/net/can/spi/mcp251x.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/can/spi/mcp251x.c b/drivers/net/can/spi/mcp251x.c
index 34c625e..117e78f 100644
--- a/drivers/net/can/spi/mcp251x.c
+++ b/drivers/net/can/spi/mcp251x.c
@@ -1085,8 +1085,8 @@ static int mcp251x_can_probe(struct spi_device *spi)
 	if (ret)
 		goto out_clk;
 
-	priv->power = devm_regulator_get(&spi->dev, "vdd");
-	priv->transceiver = devm_regulator_get(&spi->dev, "xceiver");
+	priv->power = devm_regulator_get_optional(&spi->dev, "vdd");
+	priv->transceiver = devm_regulator_get_optional(&spi->dev, "xceiver");
 	if ((PTR_ERR(priv->power) == -EPROBE_DEFER) ||
 	    (PTR_ERR(priv->transceiver) == -EPROBE_DEFER)) {
 		ret = -EPROBE_DEFER;
-- 
2.4.1

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

[Stefan Agner]

Hi Marc, hi Wolfgang,

Any comment on this two patches? I don't think these have made it in any
tree...

--
Stefan

On 2015-05-18 18:33, Stefan Agner wrote:
> 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>
> ---
>  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;

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

[Marc Kleine-Budde]

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On 07/15/2015 03:05 PM, Stefan Agner wrote:
> Hi Marc, hi Wolfgang,
> 
> Any comment on this two patches? I don't think these have made it in any
> tree...

Sorry - Should I add stable in Cc for 1/2 or even both?

Marc

-- 
Pengutronix e.K.                  | Marc Kleine-Budde           |
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Vertretung West/Dortmund          | Fax:   +49-5121-206917-5555 |
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Re: [PATCH 1/2] can: mcp251x: fix resume when device is down

[Stefan Agner]

On 2015-07-15 15:15, Marc Kleine-Budde wrote:
> On 07/15/2015 03:05 PM, Stefan Agner wrote:
>> Hi Marc, hi Wolfgang,
>>
>> Any comment on this two patches? I don't think these have made it in any
>> tree...
> 
> Sorry - Should I add stable in Cc for 1/2 or even both?

2/2 does not fix an actual issue, it only prevents dummy regulators
being created. It even has a slight potential of a regression, in case
the absence of a dummy regulator could not be handled properly...

But 1/2 is definitely stable material.

--
Stefan