On 07/24/2010 10:40 PM, Fawad Lateef wrote:
> On Sat, Jul 24, 2010 at 8:29 PM, Wolfgang Grandegger 
> <[email protected]>wrote:
> 
>> On 07/24/2010 09:15 PM, Fawad Lateef wrote:
>>> On Sat, Jul 24, 2010 at 7:10 PM, Wolfgang Grandegger <[email protected]
>>> wrote:
>>
>> ...
>>
>>>> I'm curious why you did re-write the driver. Did you try the mcp251x
>>>> driver from the mainline kernel? What problems did you encounter?
>>>>
>>>> Thanks,
>>>>
>>>> Wolfgang.
>>>>
>>>
>>>
>>> I used latest socket-can from git (and I think this is same as the driver
>> in
>>> latest kernel, right ?). I found that this synchronous driver is not
>> giving
>>
>> Do you mean Socket-CAN from the SVN repository? Unfortunately, it's not
>> the same driver then in mainline any more. It uses IRQ threads instead
>> of work queues.
>>
>>
> Why socket-can driver and mainline kernel driver are different ? I just
> looked at the diff between socket-can svn driver and linux-2.6.34.1 driver
> and noticed this change. I wasn't aware of this request_threaded_irq
> functionality in kernel. Thanks for the information.

Yes, I agree, that's confusing. IIRC. The driver in the SVN repos are
mainly for backward compatibility. Threaded-interrupts are not available
in old kernels and therefore the SVN repos was not updated. I will add
some notes to the SVN driver.

>>> performance according to our requirements and if bus is overloaded when
>>> generating packets from other CAN controller like from PEAK or CAN-Modul
>>> then system response to external events like ssh takes too much time in
>>> responding. Almost a year ago one of our engineer wrote Asynchronous
>> driver
>>> using old mcp251x driver which performs very well, but error handling in
>>> that was very bad which lock-down the system.
>>>
>>> So recently referencing that Async driver I re-wrote tx and rx path (sort
>> of
>>> merging our Async and latest Sync processing) in latest mcp251x driver
>> from
>>> socket-can. Now till now everything is very well with modified driver.
>>
>> Does it apply to the new driver in mainline?
>>
>> Wolfgang.
>>
> 
> I haven't tested this latest mainline kernel driver, but I doubt this will
> behave somewhat similar due to its synchronous functionality. Will give this
> a try soon.

That would be nice, indeed.

> Also some weeks ago when I asked some questions about Async implementation
> in mcp251x driver then AFAIR Christian replied that he like to see Async
> driver implementation.

OK, any effort to improve the driver is welcome.

Thanks,

Wolfgang.
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