Re: pch_can: Data transmission stops after dropped packet

[Marc Kleine-Budde <mkl@pengutronix.de>]

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On 12/06/2012 11:02 PM, Wolfgang Grandegger wrote:
> Hi Michael,
> 
> On 12/06/2012 06:05 PM, Alexander Stein wrote:
>> Hi Michael,
>> 
>> On Thursday 06 December 2012 15:49:03, Wolfgang Grandegger wrote:
>>>> Details of the soak test:
>>>> 
>>>> There are two systems involved in the test: the PCH-System and
>>>> an External Node. The External Node transmits data at a high
>>>> rate, bringing bus utilization to ~35%. The PCH-System also
>>>> transmits data, in bursts of 10 messages every 5 ms. Combined,
>>>> the two systems utilize ~90% of bus bandwidth. The PCH-System
>>>> is constantly checking that it is receiving data from the 
>>>> External Node at the expected rate and in the expected order.
>> 
>> So you do a lot of transmit and reception of CAN frames?
>> 
>>> On another thread Alexander is reporting problems with the same
>>> driver when he runs a I2C application concurrently. Are you able
>>> to stress the system in a similar way?
>> 
>> Could you please test with the following patch? Do you see error
>> messages from this patch? Thanks!
> 
> To summarize my understanding of your problem(s). As long as there
> are no I2C transfers, everything works fine, right? The patch below
> does report some write-readback failures but that's due to reserved
> read-only bits. I assume t hat you also use my "RFC v2" patches for
> c_can.
> 
> Trouble starts with concurrent I2C transfers. Then the protected 
> write-readback test fails, which I regard as abnormal hardware
> behavior, resulting in message losses and out-of-order reception.

Out-of-sequence reception might be a problem due to a problem in the rx
algorithm. And the drops are probably due to overflowing rx mailboxes.
The out-of-sequence will most mist likely occur if the rx fifo runs
full, but does not overflow.

Marc

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