Re: What are you doing if the TX buffer overflows?

[Wolfgang Grandegger <wg@grandegger.com>]

On 09/18/2012 02:37 PM, Wolfgang Grandegger wrote:
> On 09/17/2012 03:58 PM, Heinz-Jürgen Oertel wrote:
>>
>> Hello,
>> is there a way to empty the tx buffer ?
>> Or read out the occupied size of it
>> to get the mumber of CAN frames waiting for transmission?
> 
> As we usally get a TX done interrupt we in principle know how much
> messages are still pending in the software and hardware queue but we
> will only be able to flush the messages in the software queue because
> aborting of messages in the device TX queue is not supported (even if
> most controllers can do it). Therefore the only clean way to get rid of
> all pending messages is to stop and restart the device (ifconfig down ->
> up).
> 
> Other protocols seem to provide the ioctl request SIOCINQ to query the
> number of untransmitted messages, e.g.:
> 
>  http://lxr.linux.no/#linux+v3.5.4/net/packet/af_packet.c#L3385
> 
> Should not be a big deal to add it to the CAN ioctl requests.

SIOCINQ is for RX. SIOCOUTQ for TX.

Wolfgang.