Re: can4linux compilation for i.mx25 under 2.6.39

[Martin Kozusky <mkozusky@kkmicro.cz>]

Dne 31.5.2012 18:28, Oliver Hartkopp napsal(a):
>
>>>>>>> No, CAN has it's own thread, which is just making struct from can
>>>>>>> messages (reading via select() )  and writes them into another buffer.
>>>>>>> Then the main thread reads this buffer and writes to SD card. Now I
>>>>>>> changed it so that this buffer is 30MB big, so I first store all the
>>>>>>> messages into RAM, and when I don't need to record CAN frames
>>>>>>> anymore, I
>>>>>>> write all of them to card from this big buffer.
>>>>>>> But this is just limited workaround because I'm limited with the RAM
>>>>>>> size (so I had to make the buffer cyclic and just latest xxxx messages
>>>>>>> are stored, older are overwritten when the buffer is full).
>>>>>>
>>>>>> Have you setup realtime priorities for you CAN thread?
>>>>> No, I did't set up any special attributes. Do you mean I should use
>>>>> pthread_attr_setschedpolicy(ptr,SCHED_RR) or something else?
>>>>
>>>> or better SCHED_FIFO for your can thread.
>>> Hello Marc,
>>> I tried that and still when I write
>>> dd if=/dev/zero of=/mnt/mmcblk0p1/test bs=512 count=10000 (copy 5MB to
>>> SD card)  around 300 CAN frames (from 68500 frames) are lost :(
>>
>> http://man7.org/linux/man-pages/man2/recvmmsg.2.html
>>
>> Maybe you can use recvmmsg(). I don't know if it works already on can
>> sockets.
>
>
> I wonder, if accessing the MMC/SD card leads to a long-time blocking of
> interrupts and therefore lost frames on controller level.
>
> Looks like the flexcan RX FIFO overflow is documented here:
> http://lxr.linux.no/#linux+v3.4/drivers/net/can/flexcan.c#L603
>
> Martin, can you check the overflow counters with
>
> ifconfig can0
>
> or
>
> ip -statistics link show can0
>
> after the problem with writing to the MMC/SD card showed up?

Hello Oliver,
I just configured can0 with canconfig (speed to 250kbs) and canconfig 
can0 start
(BTW: what does  "can0 state: ERROR-ACTIVE" mean after I write canconfig 
can0 start? )

Then I started sending CAN packets. I sent 39660 packets to CAN, but 
only 35734 were received by the CAN layer?

this is what is shown (without any app running)

root@vmx25 /opt$ ./ip -statistics link show can0
2: can0: <NOARP,UP,LOWER_UP,ECHO> mtu 16 qdisc pfifo_fast state UNKNOWN 
mode DEFAULT qlen 10
     link/can
     RX: bytes  packets  errors  dropped overrun mcast
     280440     35734    6       0       6       0
     TX: bytes  packets  errors  dropped carrier collsns
     0          0        0       0       0       0

And this is show when I copy 5MB to SD card with dd. This time 39347 
packets where sent from my app.

2: can0: <NOARP,UP,LOWER_UP,ECHO> mtu 16 qdisc pfifo_fast state UNKNOWN 
mode DEFAULT qlen 10
     link/can
     RX: bytes  packets  errors  dropped overrun mcast
     152197     19335    21      0       21      0
     TX: bytes  packets  errors  dropped carrier collsns
     0          0        0       0       0       0

Should I try to backport the latest flexcan.c to my 2.6.39 kernel and 
see if it helps?

Martin

> Regards,
> Oliver
> --
> To unsubscribe from this list: send the line "unsubscribe linux-can" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>