From mboxrd@z Thu Jan  1 00:00:00 1970
From: Wolfgang Grandegger <wg@grandegger.com>
Subject: Re: What are you doing if the TX buffer overflows?
Date: Tue, 18 Sep 2012 15:25:18 +0200
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To: =?ISO-8859-1?Q?Heinz-J=FCrgen_Oertel?= <oe@port.de>
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On 09/18/2012 02:37 PM, Wolfgang Grandegger wrote:
> On 09/17/2012 03:58 PM, Heinz-J=FCrgen 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?
>=20
> 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).
>=20
> Other protocols seem to provide the ioctl request SIOCINQ to query th=
e
> number of untransmitted messages, e.g.:
>=20
>  http://lxr.linux.no/#linux+v3.5.4/net/packet/af_packet.c#L3385
>=20
> Should not be a big deal to add it to the CAN ioctl requests.

SIOCINQ is for RX. SIOCOUTQ for TX.

Wolfgang.