Re: [Xenomai-help] RTCAN and tsc

[Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>]

Sebastian Smolorz wrote:
> Gilles Chanteperdrix wrote:
> 
>>Sebastian Smolorz wrote:
>>
>>>If an RX interrupt appears it it necessary to read out up to 14 SJA1000
>>>regs and write one register before a CAN message can be distributed to
>>>the sockets. Do you really suggest that the reading of the SJA1000
>>>registers should be interruptible? One step towards chaos, I would say.
>>
>>Maybe it would make sense to handle the message reception in a thread (a
>>kind of bottom half), and to only disable the CAN irq when doing the
>>reception work. This way, the system would still be able to handle other
>>events while the can reception takes place.
> 
> 
> The SJA1000 interrupt handler consists of several parts:
> 1. Read out the interrupt register to determine which kind of CAN interrupt 
> raised
> 2. Check for the different kind of interrupts (error, TX, RX)
> 3. If RX:
> 3a. read out HW registers
> 3b. Distribute to sockets
> 
> It seems that an extended amount of time is spent for 3a. If we do this in a 
> bottom-half we have to deal with things like priority inversion and under 
> certain circumstances with lost CAN messages due to a full HW RX buffer of 
> the CAN controller.
> 

So, maybe it is possible to simply enable interrupts in the interrupt
handler with only the CAN interrupt disabled ?


-- 
                                                 Gilles Chanteperdrix