On 02/08/2011 10:04 AM, Bhupesh SHARMA wrote:
> Hi Wolfgang,
>
>>> + stats->rx_errors++;
>>> + cf->can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR;
>>> + cf->data[2] |= CAN_ERR_PROT_UNSPEC;
>>> +
>>> + switch (lec_type) {
>>> + case LEC_STUFF_ERROR:
>>> + netdev_dbg(dev, "stuff error\n");
>>> + cf->data[2] |= CAN_ERR_PROT_STUFF;
>>> + break;
>>> +
>>> + case LEC_FORM_ERROR:
>>> + netdev_dbg(dev, "form error\n");
>>> + cf->data[2] |= CAN_ERR_PROT_FORM;
>>> + break;
>>> +
>>> + case LEC_ACK_ERROR:
>>> + netdev_dbg(dev, "ack error\n");
>>> + cf->data[2] |= (CAN_ERR_PROT_LOC_ACK |
>>> + CAN_ERR_PROT_LOC_ACK_DEL);
>>> + break;
>>> +
>>> + case LEC_BIT1_ERROR:
>>> + netdev_dbg(dev, "bit1 error\n");
>>> + cf->data[2] |= CAN_ERR_PROT_BIT1;
>>> + break;
>>> +
>>> + case LEC_BIT0_ERROR:
>>> + netdev_dbg(dev, "bit0 error\n");
>>> + cf->data[2] |= CAN_ERR_PROT_BIT0;
>>> + break;
>>> +
>>> + case LEC_CRC_ERROR:
>>> + netdev_dbg(dev, "CRC error\n");
>>> + cf->data[2] |= (CAN_ERR_PROT_LOC_CRC_SEQ |
>>> + CAN_ERR_PROT_LOC_CRC_DEL);
>>> + break;
>>> + }
>
>>From the C_CAN manual:
>>
>> "The LEC field holds a code which indicates the type of the last error
>> to occur on the CAN bus. This field will be cleared to '0' when a
>> message has been transferred (reception or transmission) without error.
>> The unused code '7' may be written by the CPU to check for updates."
>
>> Not sure if it's necessary to reset the lec at init and after an error
>> to 0x7 and check it. More below...
>
> I worked on your suggestion and instead found that the follow algo must be
> used
> for reading updated `lec` values:
> a. Init lec by 0x07 at start.
> b. In function `c_can_err` check if lec is 0x7 (no bus error since this value
> was
> written by CPU on status register) or 0x0 (no error). If so, return without
> sending an error frame on stack. Else, check for the lec error type and
> submit error frame on stack accordingly.
> c. In case a lec error is found and served in `c_can_err` routine, write
> lec value to 0x07 again in status reg to check for updated lec later.
>
> This is my understanding after reading the specs time and again and
> implementing/testing the logic.
>
> Do you think this is fine or do you have any better approach?
That's what I remember from the CC770 driver. Search for lec in:
http://svn.berlios.de/wsvn/socketcan/trunk/kernel/2.6/drivers/net/can/cc770/cc770.c
Wolfgang.
_______________________________________________
Socketcan-core mailing list
[email protected]
https://lists.berlios.de/mailman/listinfo/socketcan-core
