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Date: Mon, 04 Aug 2014 16:27:49 +0200
From: Marc Kleine-Budde <mkl@...gutronix.de>
To: Stefan Agner <stefan@...er.ch>
CC: shawn.guo@...escale.com, kernel@...gutronix.de,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
linux-can@...r.kernel.org
Subject: Re: [PATCH v3 4/4] can: flexcan: add vf610 support for FlexCAN
On 08/04/2014 03:43 PM, Stefan Agner wrote:
[...]
>> Thanks for the test, so far looks promising :) With this setup the other
>> CAN node repeats the CAN frame until it's ACKed. Because there is no
>> node with a compatible bitrate, there is no ACking CAN node.
>>
>> Can you add a third CAN node to the network. The second and third node
>> should use the same bitrate, while your vf610 uses a different one. With
>> the new setup it should take more than one frame until the vf610 goes
>> into error warning and even more frames to error passive. This way we
>> can see it the error warning interrupt is connected or not. The error
>> counters should increase with each "wrong" bitrate frame it sees, you
>> can check with:
>>
>> ip -details link show can0
>>
>> The output looks like this:
>>
>>> 4: can0: <NOARP,UP,LOWER_UP,ECHO> mtu 16 qdisc pfifo_fast state UNKNOWN mode DEFAULT qlen 10
>>> link/can
>>> can state ERROR-ACTIVE (berr-counter tx 0 rx 0) restart-ms 0
>> ^^^^^^^^^^^^^^^^^^^^^^
>>> bitrate 1000000 sample-point 0.750
>>> tq 125 prop-seg 2 phase-seg1 3 phase-seg2 2 sjw 1
>>> sja1000: tseg1 1..16 tseg2 1..8 sjw 1..4 brp 1..64 brp-inc 1
>>> clock 8000000
>>
>> When one of the berr-counter crosses 96 (and stays below 128) a warning
>> interrupt should be generated.
>
> Ok, created this setup, could successfully communicate with all three
> nodes. I then set the Vybrid to half of the bitrate. When I send a frame
> from Vybrid, the berr-counter tx immediately ends up at 128 and the
> device is in ERROR-PASSIVE:
This is expected.
> root@...ibri-vf:~# ip -details link show can1
> 3: can1: <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 0 rx 0) restart-ms 0
> bitrate 124990 sample-point 0.739
> tq 347 prop-seg 8 phase-seg1 8 phase-seg2 6 sjw 1
> flexcan: tseg1 4..16 tseg2 2..8 sjw 1..4 brp 1..256 brp-inc 1
> clock 83368421
^^^^^^^^
BTW: the can core has a really weird clock rate, have a look at the
datasheet if you manage to route a 24 MHz clock (or another multiple of
8MHz) to the flexcan core. I had a quick glance at the datasheet, if I
understand it correctly the Fast OSC clock runs with 24 MHz.
> root@...ibri-vf:~# cansend can1 1F334455#1122334455667788
> interface = can1, family = 29, type = 3, proto = 1
> root@...ibri-vf:~# [ 818.886664] flexcan_irq, esr=00062242
> [ 818.890365] flexcan_irq, ctrl=1c3dac57
>
> root@...ibri-vf:~# ip -details link show can1
> 3: can1: <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-PASSIVE (berr-counter tx 128 rx 0) restart-ms 0
> bitrate 124990 sample-point 0.739
> tq 347 prop-seg 8 phase-seg1 8 phase-seg2 6 sjw 1
> flexcan: tseg1 4..16 tseg2 2..8 sjw 1..4 brp 1..256 brp-inc 1
> clock 83368421
>
>
> When I send the frames from another device on the bus, I can see the rx
> count incrementing by one on each frame I send. As you expected, the
> device changes to ERROR-WARNING when crossing the 96 frame boundary:
This is correct
> root@...ibri-vf:~# ip -details link show can1
> 3: can1: <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 0 rx 92) restart-ms 0
> bitrate 124990 sample-point 0.739
> tq 347 prop-seg 8 phase-seg1 8 phase-seg2 6 sjw 1
> flexcan: tseg1 4..16 tseg2 2..8 sjw 1..4 brp 1..256 brp-inc 1
> clock 83368421
> root@...ibri-vf:~# [ 448.331150] flexcan_irq, esr=0005050a
> [ 448.334851] flexcan_irq, ctrl=1c3dac57
> ip -details link show can1
> 3: can1: <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-WARNING (berr-counter tx 0 rx 102) restart-ms 0
> bitrate 124990 sample-point 0.739
> tq 347 prop-seg 8 phase-seg1 8 phase-seg2 6 sjw 1
> flexcan: tseg1 4..16 tseg2 2..8 sjw 1..4 brp 1..256 brp-inc 1
> clock 83368421
> However, once reaching 128, I don't get another interrupt and the device
> stays in ERROR-WARNING:
The contents of the esr reg would be interesting, especially the
FLT_CONF part.
> 3: can1: <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-WARNING (berr-counter tx 0 rx 128) restart-ms 0
> bitrate 124990 sample-point 0.739
> tq 347 prop-seg 8 phase-seg1 8 phase-seg2 6 sjw 1
> flexcan: tseg1 4..16 tseg2 2..8 sjw 1..4 brp 1..256 brp-inc 1
> clock 83368421
>
> Is this the expected behavior on receive?
No, it should go into error passive if one of the error counters have >
127. Maybe this is an error onthe vf610, maybe it's a general flexcan
problem.
Marc
--
Pengutronix e.K. | Marc Kleine-Budde |
Industrial Linux Solutions | Phone: +49-231-2826-924 |
Vertretung West/Dortmund | Fax: +49-5121-206917-5555 |
Amtsgericht Hildesheim, HRA 2686 | http://www.pengutronix.de |
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