From: Oliver Hartkopp <socketcan@hartkopp.net>
To: Jeroen Hofstee <jhofstee@victronenergy.com>,
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: Wed, 2 Dec 2020 15:35:22 +0100 [thread overview]
Message-ID: <0988dd09-70d9-3ee8-9945-10c4dea49407@hartkopp.net> (raw)
In-Reply-To: <f5f93e72-c55f-cfd3-a686-3454e42c4371@victronenergy.com>
Hi Jeroen,
On 27.11.20 12:09, Jeroen Hofstee wrote:
> 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++;
I can confirm with CAN_CTRLMODE_ONE_SHOT active and the patch ("can:
sja1000: sja1000_err(): don't count arbitration lose as an error")
https://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can.git/commit/?h=testing&id=bd0ccb92efb09c7da5b55162b283b42a93539ed7
I now get ONE(!) increment for tx_errors and ONE increment in the
arbitration-lost counter.
Before the above patch I had TWO tx_errors for each arbitration lost case.
> 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.
Do we agree that in one-shot mode both the tx_errors and the
arbitration_lost counters are increased in the arbitration-lost case?
At least this would fit to the Kvaser USB behaviour.
And btw. I wondered if we should remove the check for
CAN_CTRLMODE_ONE_SHOT here, as we ALWAYS should count a tx_error and
drop the echo_skb when we have a TX-interrupt and TX-complete flag is zero.
So replace:
if (priv->can.ctrlmode & CAN_CTRLMODE_ONE_SHOT &&
!(status & SR_TCS)) {
with:
if (!(status & SR_TCS)) {
Any suggestions?
Best regards,
Oliver
next prev parent reply other threads:[~2020-12-02 14:38 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
2020-12-02 14:35 ` Oliver Hartkopp [this message]
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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