From: Jeroen Hofstee <jhofstee@victronenergy.com>
To: Oliver Hartkopp <socketcan@hartkopp.net>,
Marc Kleine-Budde <mkl@pengutronix.de>,
linux-can@vger.kernel.org
Cc: Chen-Yu Tsai <wens@csie.org>,
Jernej Skrabec <jernej.skrabec@siol.net>,
"open list:NETWORKING DRIVERS" <netdev@vger.kernel.org>,
"moderated list:ARM/Allwinner sunXi SoC support"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH] can: don't count arbitration lose as an error
Date: Sun, 29 Nov 2020 16:52:17 +0100 [thread overview]
Message-ID: <4319bb31-972c-78e1-ec20-11fdfd04d6bd@victronenergy.com> (raw)
In-Reply-To: <042ad21c-e238-511b-1282-2ea226e572ff@hartkopp.net>
Hello Oliver,
On 11/28/20 6:23 PM, Oliver Hartkopp wrote:
>
>
> On 27.11.20 12:09, Jeroen Hofstee wrote:
>> Hi,
>>
>> On 11/27/20 11:30 AM, Marc Kleine-Budde wrote:
>>> On 11/27/20 10:59 AM, Jeroen Hofstee wrote:
>>>> Losing arbitration is normal in a CAN-bus network, it means that a
>>>> higher priority frame is being send and the pending message will be
>>>> retried later. Hence most driver only increment arbitration_lost, but
>>>> the sja1000 and sun4i driver also incremeant tx_error, causing errors
>>>> to be reported on a normal functioning CAN-bus. So stop counting them
>>>> as errors.
>>> Sounds plausible.
>>>
>>>> For completeness, the Kvaser USB hybra also increments the tx_error
>>>> on arbitration lose, but it does so in single shot. Since in that
>>>> case the message is not retried, that behaviour is kept.
>>> You mean only in one shot mode?
>>
>> Yes, well at least the function is called
>> kvaser_usb_hydra_one_shot_fail.
>>
>>
>>> What about one shot mode on the sja1000 cores?
>>
>>
>> That is a good question. I guess it will be counted as error by:
>>
>> if (isrc & IRQ_TI) {
>> /* transmission buffer released */
>> if (priv->can.ctrlmode & CAN_CTRLMODE_ONE_SHOT &&
>> !(status & SR_TCS)) {
>> stats->tx_errors++;
>> can_free_echo_skb(dev, 0);
>> } else {
>> /* transmission complete */
>> stats->tx_bytes +=
>> priv->read_reg(priv, SJA1000_FI) & 0xf;
>> stats->tx_packets++;
>> can_get_echo_skb(dev, 0);
>> }
>> netif_wake_queue(dev);
>> can_led_event(dev, CAN_LED_EVENT_TX);
>> }
>>
>> From the datasheet, Transmit Interrupt:
>>
>> "set; this bit is set whenever the transmit bufferstatus
>> changes from ‘0-to-1’ (released) and the TIE bit is set
>> within the interrupt enable register".
>>
>> I cannot test it though, since I don't have a sja1000.
>
> I have a PCAN-ExpressCard 34 here, which should make it in a test
> setup as it acts as a PCI attached SJA1000.
>
> Will take a look at that arbitration lost behaviour on Monday. A
> really interesting detail!
>
>
Thanks, appreciated. I would be surprised if this path is not taken though.
With kind regards,
Jeroen
next prev parent reply other threads:[~2020-11-29 15:53 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-27 9:59 [PATCH] can: don't count arbitration lose as an error Jeroen Hofstee
2020-11-27 10:30 ` Marc Kleine-Budde
2020-11-27 11:09 ` Jeroen Hofstee
2020-11-27 16:02 ` Jeroen Hofstee
2020-11-28 17:23 ` Oliver Hartkopp
2020-11-29 15:52 ` Jeroen Hofstee [this message]
2020-12-02 14:35 ` Oliver Hartkopp
2020-12-02 15:37 ` Jeroen Hofstee
2020-12-02 16:22 ` Oliver Hartkopp
2020-12-02 16:31 ` Jeroen Hofstee
2020-11-30 11:50 ` Marc Kleine-Budde
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