Date:   Wed, 15 Mar 2017 00:44:20 -0400
From:   Akshay Bhat <nodeax@...il.com>
To:     Wolfgang Grandegger <wg@...ndegger.com>
Cc:     Akshay Bhat <akshay.bhat@...esys.com>, mkl@...gutronix.de,
        linux-can@...r.kernel.org, netdev@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/2] can: spi: hi311x: Add Holt HI-311x CAN driver

Hi Wolfgang,

On Tue, Mar 14, 2017 at 2:08 PM, Wolfgang Grandegger <wg@...ndegger.com> wrote:
...snip....
>> /////disconnect cable
>>   can0  20000088   [8]  00 00 00 19 00 00 28 00   ERRORFRAME
>>         protocol-violation{{}{acknowledge-slot}}
>>         bus-error
>>         error-counter-tx-rx{{40}{0}}
>>   can0  20000088   [8]  00 00 00 19 00 00 58 00   ERRORFRAME
>>         protocol-violation{{}{acknowledge-slot}}
>>         bus-error
>>         error-counter-tx-rx{{88}{0}}
>>   can0  20000088   [8]  00 00 00 19 00 00 80 00   ERRORFRAME
>>         protocol-violation{{}{acknowledge-slot}}
>>         bus-error
>>         error-counter-tx-rx{{128}{0}}
>
>
> TX error warning is missing.
>

This support was missing in the driver, added in V4 patch.

>>   can0  2000008C   [8]  00 20 00 19 00 00 80 00   ERRORFRAME
>>         controller-problem{tx-error-passive}
>>         protocol-violation{{}{acknowledge-slot}}
>>         bus-error
>>         error-counter-tx-rx{{128}{0}}
>
>
> Here "tx-error-passiv" is packed with a bus error. What I'm looking for are
> state change messages similar to:
>
>    can0  20000204  [8] 00 08 00 00 00 00 60 00   ERRORFRAME
>         controller-problem{tx-error-warning}
>         state-change{tx-error-warning}
>         error-counter-tx-rx{{96}{0}}
>    can0  20000204  [8] 00 30 00 00 00 00 80 00   ERRORFRAME
>         controller-problem{tx-error-passive}
>         state-change{tx-error-passive}
>         error-counter-tx-rx{{128}{0}
>
> They should always come, even with "berr-reporting off".
>

HI-3110 has only 1 bus error interrupt. There is no dedicated state
change interrupts like other controllers.

So here is my plan:
- Have the bus error interrupt always enabled
- If berr-reporting off, then have the isr checks/reports state changes
- if berr-reporting on, then have the isr checks/reports bus errors
and state changes (Does it make sense packing the error message, if
the ISR finds both bus and state changes?)

>> write: No buffer space available
>> root@...6qrom5420b1:~# ip -s -d link show can0
>> 4: can0: <NOARP,UP,LOWER_UP,ECHO> mtu 16 qdisc pfifo_fast state UNKNOWN
>> mode DEFAULT group default qlen 10
>>     link/can  promiscuity 0
>>     can <BERR-REPORTING> state ERROR-PASSIVE (berr-counter tx 128 rx 0)
>> restart-ms 0
>>           bitrate 1000000 sample-point 0.750
>>           tq 62 prop-seg 5 phase-seg1 6 phase-seg2 4 sjw 1
>>           hi3110: tseg1 2..16 tseg2 2..8 sjw 1..4 brp 1..64 brp-inc 1
>>           clock 16000000
>>           re-started bus-errors arbit-lost error-warn error-pass bus-off
>>           0          6          0          1          1          0
>
>
> The error warning and passive counter increased , though. Also the bus error
> should come in at a rather hight rate. Looking to the code, maybe
> you need to test STATF to check for state changes (and not ERR).
>

Apologize, just realized In the above case some error packets were
lost, because I forgot to set the CPU frequency to max. Will resend
the log.

..snip...
>
> After some more messages there should be also:
>
>     can0  20000200  [8] 00 40 00 00 00 00 5F 00   ERRORFRAME
>         state-change{back-to-error-active}
>         error-counter-tx-rx{{95}{0}}
>
> For each message sent, the error counter decreases by 8.
>

The HI-3110 controller decrements the error counter by 1 for every message sent.
The error count increments by 8 when there is an error.

>
>>
>> root@...6qrom5420b1:~# ip -s -d link show can0
>> 4: can0: <NOARP,UP,LOWER_UP,ECHO> mtu 16 qdisc pfifo_fast state UNKNOWN
>> mode DEFAULT group default qlen 10
>>     link/can  promiscuity 0
>>     can state ERROR-ACTIVE (berr-counter tx 117 rx 0) restart-ms 0
>>           bitrate 1000000 sample-point 0.750
>>           tq 62 prop-seg 5 phase-seg1 6 phase-seg2 4 sjw 1
>>           hi3110: tseg1 2..16 tseg2 2..8 sjw 1..4 brp 1..64 brp-inc 1
>>           clock 16000000
>>           re-started bus-errors arbit-lost error-warn error-pass bus-off
>>           0          1          0          0          0          0
>
>
> Strange, some counters got lost.
>

This was a bug introduced when adding berr-reporting, have fixed in v4 patch.

>>
>> I have not been able to check the bus-off condition by (short-circuiting
>> CAN low and high). The tec error count remains at 128 when I short the
>> CAN low and high pins and the status never goes BUSOFF.
>
>
> You also need to send a message and the short-circuit should be at the
> connector of the sending host. What tranceiver is used? Do you know?
>

ADM3054 transceiver is used with HI-3111. I connected the
HI-3111/ADM3054 board to kvaser leaf and ran "cangen -i can0" and
"candump -e any,0:0,#FFFFFFF" on the board. Removed the cable and
shorted the CAN_H/L pins coming out of ADM3054. I will try your
suggestion of using a different bit-rate on the Kvaser leaf instead.

I appreciate your continued feedback, it has helped significantly
improve the error handling of the driver. Looking back I should have
based it on sja1000 or flexcan driver.

Thanks,
Akshay

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