Re: pch_can: Data transmission stops after dropped packet

[Wolfgang Grandegger <wg@grandegger.com>]

Hi Michael,

On 11/20/2012 08:12 PM, Michael Pellegrini wrote:
> Wolfgang Grandegger <wg <at> grandegger.com> writes:
> 
>>>
>>> However, everything isn't fixed yet.  After sending a handful of messages, 
> the 
>>> CAN interface hits the same problem that started this thread.  My 
> application 
>>> prints the error "No buffer space available" and the only way to recover is 
> an 
>>> interface reset via "ifconfig can0 down" followed by "ifconfig can0 up".
>>
>> Could you please send the output of "candump any,0:0,#FFFFFFFF" while
>> sending the messages. Do they go out to the bus? Also "ip -d -s link
>> show can0" would be useful.
> 
> candump produced no output while my application was running and trying to send
> messages.  Furthermore, the lack of output from candump suggests that messages
> aren't being received as well.  There is another CAN device on the bus and I can
> confirm, using a CAN monitor tool on another PC, that it is actively sending
> messages.
> 
> Upon starting my application, 16 messages are transmitted on the bus (confirmed
> via the external CAN monitor tool) which candump does not report.  Then
> transmission stops.  This lines up with the output of "ip -d -s link show can0",
> shown below:

I'm a bit confused. Where is the application running? On this
PCH-System? Or does an external node send messages, which are not
received by the PCH-C_CAN?

> At startup:
> 
> 4: can0: <NOARP,UP,LOWER_UP,ECHO> mtu 16 qdisc pfifo_fast state UNKNOWN qlen 10
>     link/can
>     can state ERROR-ACTIVE (berr-counter tx 0 rx 0) restart-ms 0
>     bitrate 250000 sample-point 0.875
>     tq 500 prop-seg 3 phase-seg1 3 phase-seg2 1 sjw 1
>     c_can: tseg1 2..16 tseg2 1..8 sjw 1..4 brp 1..1024 brp-inc 1
>     clock 50000000
>     re-started bus-errors arbit-lost error-warn error-pass bus-off
>     0          0          0          0          0          0
>     RX: bytes  packets  errors  dropped overrun mcast
>     0          0        0       0       0       0
>     TX: bytes  packets  errors  dropped carrier collsns
>     0          0        0       0       0       0
> 
> After transmission stops:
> 
> 4: can0: <NOARP,UP,LOWER_UP,ECHO> mtu 16 qdisc pfifo_fast state UNKNOWN qlen 10
>     link/can
>     can state ERROR-ACTIVE (berr-counter tx 0 rx 0) restart-ms 0
>     bitrate 250000 sample-point 0.875
>     tq 500 prop-seg 3 phase-seg1 3 phase-seg2 1 sjw 1
>     c_can: tseg1 2..16 tseg2 1..8 sjw 1..4 brp 1..1024 brp-inc 1
>     clock 50000000
>     re-started bus-errors arbit-lost error-warn error-pass bus-off
>     0          0          0          0          0          0
>     RX: bytes  packets  errors  dropped overrun mcast
>     0          0        0       0       0       0
>     TX: bytes  packets  errors  dropped carrier collsns
>     0          0        0       0       0       0
> 
> After transmission stops & interface is reset:
> 
> 4: can0: <NOARP,UP,LOWER_UP,ECHO> mtu 16 qdisc pfifo_fast state UNKNOWN qlen 10
>     link/can
>     can state ERROR-ACTIVE (berr-counter tx 0 rx 0) restart-ms 0
>     bitrate 250000 sample-point 0.875
>     tq 500 prop-seg 3 phase-seg1 3 phase-seg2 1 sjw 1
>     c_can: tseg1 2..16 tseg2 1..8 sjw 1..4 brp 1..1024 brp-inc 1
>     clock 50000000
>     re-started bus-errors arbit-lost error-warn error-pass bus-off
>     0          0          0          0          0          0
>     RX: bytes  packets  errors  dropped overrun mcast
>     0          0        0       0       0       0
>     TX: bytes  packets  errors  dropped carrier collsns
>     0          0        0       16      0       0
> 
> The best I can tell, the 16 messages which are successfully transmitted on the
> bus are considered dropped by the driver.

OK, we still have a problem with TX and RX, most likely with interrupts.
Could you please send a message on the PCH-System executing
"cansend can0 123#abcdef":

- Does "candump any,0:0,#FFFFFFFF" report anything.

- Does the message show up on the bus (visiable to another node or
  analyser)?

- Does the interrupt count increase? Check output of /proc/interrupts.

I will prepare an instrumented driver tomorrow.

Wolfgang.