On 10/15/19 2:21 PM, Stéphane Grosjean wrote:
>>> /*
>>> * start interface
>>> */
>>> static int pcan_usb_start(struct peak_usb_device *dev) {
>>> struct pcan_usb *pdev = container_of(dev, struct pcan_usb, dev);
>>> +int err;
>>>
>>> /* number of bits used in timestamps read from adapter struct */
>>> peak_usb_init_time_ref(&pdev->time_ref, &pcan_usb);
>>>
>>> +pdev->bec.rxerr = 0;
>>> +pdev->bec.txerr = 0;
>>> +
>>> +/* be notified on any error counter change */
>>
>> Does the device offer the possibility to read the error counters? If so please
>> do it in pcan_usb_get_berr_counter().
> Nope! The value of the error counters can only be obtained through
> the below "bus error" notification mechanism:
I assume in the current kernel the device shows 0 errors, right?
How many errors will the device generate on a proper terminated bus
without a 2nd CAN device acking the send packages?
On SoC with integrated CAN controllers this will generate a huge load of
CAN frames, resulting in quite a lot of CPU load (~50%). So I'm a bit
hesitated.
>>> +err = pcan_usb_set_err_frame(dev, PCAN_USB_ERR_ECC |
>>> + PCAN_USB_ERR_RXERR |
>> PCAN_USB_ERR_TXERR |
>>> + PCAN_USB_ERR_RXERR_CNT |
>>> + PCAN_USB_ERR_TXERR_CNT);
>>
>> Better only enable bus errors, if the user has requested them. See:
>>
>> https://elixir.bootlin.com/linux/latest/source/drivers/net/can/sja1000/sja10
>> 00.c#L152
>
> Ok. But this also means that the rx/tx err counters will always be 0
> if user didn't request "berr-reporting on". Is this ok?
I tend to say yes, it doesn't change the behaviour of the driver. Can
you generate some numbers for the alone-on-the-bus scenario? Error
frames per seconds, IRQs per second.
Marc
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