On 07/20/2017 04:52 AM, Sergei Shtylyov wrote:
> Hello!
>
> On 7/20/2017 2:36 AM, Franklin S Cooper Jr wrote:
>
>> Various CAN or CAN-FD IP may be able to run at a faster rate than
>> what the transceiver the CAN node is connected to. This can lead to
>> unexpected errors. However, CAN transceivers typically have fixed
>> limitations and provide no means to discover these limitations at
>> runtime. Therefore, add support for a fixed-transceiver node that
>> can be reused by other CAN peripheral drivers to determine for both
>> CAN and CAN-FD what the max bitrate that can be used. If the user
>> tries to configure CAN to pass these maximum bitrates it will throw
>> an error.
>>
>> Signed-off-by: Franklin S Cooper Jr <fcooper@xxxxxx>
>> ---
>> drivers/net/can/dev.c | 48
>> ++++++++++++++++++++++++++++++++++++++++++++++++
>> include/linux/can/dev.h | 5 +++++
>> 2 files changed, 53 insertions(+)
>>
>> diff --git a/drivers/net/can/dev.c b/drivers/net/can/dev.c
>> index 365a8cc..fbab87d 100644
>> --- a/drivers/net/can/dev.c
>> +++ b/drivers/net/can/dev.c
> [...]
>> @@ -814,6 +830,38 @@ int open_candev(struct net_device *dev)
>> }
>> EXPORT_SYMBOL_GPL(open_candev);
>> +#ifdef CONFIG_OF
>> +void of_transceiver_is_fixed(struct net_device *dev)
>
> Strange name for a *void* function...
Ok I see what you mean since I'm not actually returning anything. I'll
go with of_can_transceiver_fixed based on your comment also Oliver's
suggestion.
> Also, I think 'struct net_device *' variables are typically called
> 'ndev'.
All other functions within this file uses struct net_device *dev. So I'm
just following the style currently used.
>
>> +{
>> + struct device_node *dn;
>> + struct can_priv *priv = netdev_priv(dev);
>> + u32 max_frequency;
>> + struct device_node *np;
>> +
>> + np = dev->dev.parent->of_node;
>> +
>> + /* New binding */
>> + dn = of_get_child_by_name(np, "fixed-transceiver");
>> + if (!dn)
>> + return;
>> +
>> + of_property_read_u32(dn, "max-arbitration-speed", &max_frequency);
>
> In case this function fails, 'max_frequency' will have no value --
> you'd better initialize it...
Thanks for catching this. Will fix.
>
>> +
>> + if (max_frequency > 0)
>> + priv->max_trans_arbitration_speed = max_frequency;
>> + else
>> + priv->max_trans_arbitration_speed = -1;
>> +
>> + of_property_read_u32(dn, "max-data-speed", &max_frequency);
>
> Again, when that function fails, the variable will keep the value
> from the previous call...
Will fix.
>
> [...]
>
> MBR, Sergei
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