On 11/13/2014 06:03 PM, Marc Kleine-Budde wrote:
> On 11/13/2014 04:23 PM, Roger Quadros wrote:
>> DRA7 CAN IP suffers from a problem which causes it to be prevented
>> from fully turning OFF (i.e. stuck in transition) if the module was
>> disabled while there was traffic on the CAN_RX line.
>>
>> To work around this issue we select the SLEEP pin state by default
>> on probe and use the DEFAULT pin state on CAN up and back to the
>> SLEEP pin state on CAN down.
>>
>> Signed-off-by: Roger Quadros <rogerq@xxxxxx>
>> ---
>> drivers/net/can/c_can/c_can.c | 37 +++++++++++++++++++++++++++++++++++++
>> drivers/net/can/c_can/c_can.h | 1 +
>> 2 files changed, 38 insertions(+)
>>
>> diff --git a/drivers/net/can/c_can/c_can.c b/drivers/net/can/c_can/c_can.c
>> index 8e78bb4..c80cb3d 100644
>> --- a/drivers/net/can/c_can/c_can.c
>> +++ b/drivers/net/can/c_can/c_can.c
>> @@ -35,6 +35,7 @@
>> #include <linux/list.h>
>> #include <linux/io.h>
>> #include <linux/pm_runtime.h>
>> +#include <linux/pinctrl/consumer.h>
>>
>> #include <linux/can.h>
>> #include <linux/can/dev.h>
>> @@ -587,6 +588,21 @@ static int c_can_chip_config(struct net_device *dev)
>> return c_can_set_bittiming(dev);
>> }
>>
>> +/*
>> + * Selects the pinctrl state specified in the name.
>> + */
>> +static void c_can_pinctrl_select_state(struct c_can_priv *priv,
>> + const char *name)
>> +{
>> + if (!IS_ERR(priv->pinctrl)) {
>> + struct pinctrl_state *s;
>> +
>> + s = pinctrl_lookup_state(priv->pinctrl, name);
>> + if (!IS_ERR(s))
>> + pinctrl_select_state(priv->pinctrl, s);
>> + }
>> +}
>> +
>> static int c_can_start(struct net_device *dev)
>> {
>> struct c_can_priv *priv = netdev_priv(dev);
>> @@ -603,6 +619,8 @@ static int c_can_start(struct net_device *dev)
>>
>> priv->can.state = CAN_STATE_ERROR_ACTIVE;
>>
>> + /* activate pins */
>> + c_can_pinctrl_select_state(priv, PINCTRL_STATE_DEFAULT);
>> return 0;
>> }
>>
>> @@ -611,6 +629,9 @@ static void c_can_stop(struct net_device *dev)
>> struct c_can_priv *priv = netdev_priv(dev);
>>
>> c_can_irq_control(priv, false);
>> +
>> + /* deactivate pins */
>> + c_can_pinctrl_select_state(priv, PINCTRL_STATE_SLEEP);
>> priv->can.state = CAN_STATE_STOPPED;
>> }
>>
>> @@ -1244,6 +1265,22 @@ int register_c_can_dev(struct net_device *dev)
>> struct c_can_priv *priv = netdev_priv(dev);
>> int err;
>>
>> + priv->pinctrl = devm_pinctrl_get(dev->dev.parent);
>
> What's dev->dev.parent?
> Ah, this is set by SET_NETDEV_DEV(dev, &pdev->dev); Good work!
>
> I thought we had to set priv->pinctrl in the platform.c.
>
>> + if (!IS_ERR(priv->pinctrl)) {
>> + struct pinctrl_state *s;
>> +
>> + /* Deactivate pins to prevent DRA7 DCAN IP from being
>> + * stuck in transition when module is disabled.
>> + * Pins are activated in c_can_start() and deactivated
>> + * in c_can_stop()
>> + */
>> + s = pinctrl_lookup_state(priv->pinctrl, PINCTRL_STATE_SLEEP);
>> + if (!IS_ERR(s))
>> + pinctrl_select_state(priv->pinctrl, s);
>> + } else {
>> + netdev_dbg(dev, "failed to get pinctrl\n");
>> + }
>> +
> The above can be replace by this?
>
> c_can_pinctrl_select_state(priv, PINCTRL_STATE_SLEEP)
Yes, indeed.
>
> Then we don't have the worrying looking error message if there isn't any
> pinctrl, e.g. for the PCI driver with pinctrl enabled in the Kernel.
>
> I just stumbled over pinctrl_pm_select_sleep_state(), is it possible to
> integrate this into runtime pm?
>
> http://lxr.free-electrons.com/source/drivers/pinctrl/core.c#L1282
I think those functions are there for the same reason but not sure why aren't
they used in runtime pm core.
Linus W. any hints?
cheers,
-roger
>
>> c_can_pm_runtime_enable(priv);
>>
>> dev->flags |= IFF_ECHO; /* we support local echo */
>> diff --git a/drivers/net/can/c_can/c_can.h b/drivers/net/can/c_can/c_can.h
>> index c6715ca..3cedf48 100644
>> --- a/drivers/net/can/c_can/c_can.h
>> +++ b/drivers/net/can/c_can/c_can.h
>> @@ -210,6 +210,7 @@ struct c_can_priv {
>> u32 comm_rcv_high;
>> u32 rxmasked;
>> u32 dlc[C_CAN_MSG_OBJ_TX_NUM];
>> + struct pinctrl *pinctrl;
>> };
>>
>> struct net_device *alloc_c_can_dev(void);
>>
>
> Marc
>
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