Messages in this thread | | | Date | Sat, 20 Mar 2010 08:55:16 +0100 | From | Wolfgang Grandegger <> | Subject | Re: [PATCH 2/3] can: add support for Janz VMOD-ICAN3 Intelligent CAN module |
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Ira W. Snyder wrote: > On Fri, Mar 19, 2010 at 09:13:37PM +0100, Wolfgang Grandegger wrote: >> Ira W. Snyder wrote: >>> On Fri, Mar 19, 2010 at 04:45:09PM +0100, Wolfgang Grandegger wrote: >>>> Ira W. Snyder wrote: >>>>> On Fri, Mar 19, 2010 at 10:01:14AM +0100, Wolfgang Grandegger wrote: >>>>>> Hi Ira, >>>>>> >>>>>> we already discussed this patch on the SocketCAN mailing list and there >>>>>> are just a few minor issues and the request to add support for the new >>>>>> "berr-reporting" option, if feasible. See: >>>>>> >>>>>> commit 52c793f24054f5dc30d228e37e0e19cc8313f086 >>>>>> Author: Wolfgang Grandegger <wg@grandegger.com> >>>>>> Date: Mon Feb 22 22:21:17 2010 +0000 >>>>>> >>>>>> can: netlink support for bus-error reporting and counters >>>>>> >>>>>> This patch makes the bus-error reporting configurable and allows to >>>>>> retrieve the CAN TX and RX bus error counters via netlink interface. >>>>>> I have added support for the SJA1000. The TX and RX bus error counters >>>>>> are also copied to the data fields 6..7 of error messages when state >>>>>> changes are reported. >>>>>> >>>>>> Should not be a big deal. >>>>>> >>>>> I think this patch came along since my last post of the driver. I must >>>>> have missed it. I'll try and add support. >>>> No problem, it's really new. Just just need to enable BEI depending on >>>> CAN_CTRLMODE_BERR_REPORTING. >>>> >>> I have one final question about this. >>> >>> The documentation for the firmware isn't very specific here. I believe >>> that in order to get any kind of error messages, I need the bus error >>> feature turned on. What is the expected behavior of an SJA1000 with the >>> BEI (bus error interrupt) turned off? Will you still get warning >>> messages for ERROR_ACTIVE -> ERROR_PASSIVE state transitions? >> Yes. State transitions are enabled with EI and EPI. >> > > I cannot set the registers directly, but I think I got it right. See > below. > >>> I'm not sure how I would go about testing this feature, either. Ideas? >> Send messages without cable connected and watch the error messages with >> "candump any,0:0,#ffffffff". With "ip ... berr-reporting on" you should >> see additional bus-errors. >> > > Ok, I tried this. On one controller, I turned on bus-error reporting. On > the other, I turn off bus-error reporting. I then tried sending lots of > messages with the cable unplugged. Here is what happened: > > bus-error reporting on: > Lots of CAN_ERR_BUSERR messages are flooded in candump. There is also a > CAN_ERR_CRTL_TX_WARNING message, when there are too many TX errors.
OK, you will now also understand why bus-error reporting is off by default. On low-end systems bus-error flooding may even hang the system.
> bus-error reporting off: > There was only one message reported before the controller went into > ERROR-WARNING state. It was the same CAN_ERR_CRTL_TX_WARNING message as > above. There was no flooding of CAN_ERR_BUSERR messages. > > Does this seem right? It seems pretty good to me.
Yes, I'm just missing an error-passive message. What state does "ip -d link show can0" report.
>>> I also noticed that I can enable "self test mode" and "listen only mode" >>> using the same firmware command. It appears that there are netlink >>> messages for this as well. Should I try and support these, too? I don't >>> really have any use for them (yet). I assume "self test mode" is >>> equivalent to "loopback mode" in the netlink messages. >> List-only is straight forward while "self test mode" is not exactly like >> "loopback mode", IIRC. Feel free to send a follow-up patch when you have >> time for a thorough implementation and testing. It's also on my to-do >> list for the SJA1000. >> > > Ok, then I'll put this off for a while. Feel free to pester me about it > when there is a working implementation in the SJA1000 driver for me to > borrow from. :)
I will let you know when I have something working.
Wolfgang.
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