Thanks David,
I'll go see if I can find a 2.6.25 kernel someplace (kernel.org seems
to be down right now) and see if I can figure out what's changed.

--wpd


On Wed, Sep 7, 2011 at 2:58 PM, David Bisset <david_bisset@btconnect.com> wrote:
> Interesting.
> I had the AUX interrupt working but under 2.6.25, but since then this code has changed.
> I rebuilt the working driver under 2.6.39-4 last week it worked, all except the interrupt. I put this down to my not being up to date.
> Interrupt names and the code in balloon.c have certainly changed between these versions.
> So I was about to start looking at this, but please go ahead on the assumption that no one has had this working under any recent kernel and that balloon.c may be in error.
> I'll not get to this till Friday, so feel free to beat me to it... :-)
>
> Kind Regards
>
> David
>
>
> On 7 Sep 2011, at 19:28, Patrick Doyle wrote:
>
>> While not trying to malign anybody, I am curious to learn if it is
>> possible that the AUX_NIRQ interrupt on the balloon3 board has never
>> been adequately tested.
>>
>> I ask because some of the code I see in arch/arm/mach-pxa/balloon3.c
>> looks just plain wrong, and because, right or wrong (I haven't even
>> gotten to that code yet), I can't seem to get my FPGA to generate an
>> interrupt that is serviced by my kernel.
>>
>> I will debug this problem differently depending on whether I should
>> assume that the code is known to work than I would if I don't have
>> that up front knowledge.
>>
>> The questionable code looks like:
>>
>> static void balloon3_irq_handler(unsigned int irq, struct irq_desc *desc)
>> {
>>       unsigned long pending = __raw_readl(BALLOON3_INT_CONTROL_REG) &
>>                                       balloon3_irq_enabled;
>>       do {
>>               /* clear useless edge notification */
>>               if (desc->chip->ack)
>>                       desc->chip->ack(BALLOON3_AUX_NIRQ);
>>               while (pending) {
>>                       irq = BALLOON3_IRQ(0) + __ffs(pending);
>>                       generic_handle_irq(irq);
>>                       pending &= pending - 1;
>>               }
>>               pending = __raw_readl(BALLOON3_INT_CONTROL_REG) &
>>                               balloon3_irq_enabled;
>>       } while (pending);
>> }
>>
>> The part that confuses me however is the line that reads:
>>
>> pending &= pending - 1;
>>
>> Shouldn't that be more like:
>>
>> pending &= ~(1 << (irq - BALLOON3_IRQ(0)))
>>
>> (I wouldn't do it exactly that way, but I'm just trying to make a point here).
>>
>> Feel free to tell me the code works fine in millions of applications
>> worldwide, and I'll continue down the path of assuming balloon3.c is
>> correct and my code is wrong.
>>
>> If I don't hear from anybody, I'm going to start assuming that
>> balloon3.c is questionable, fix things the way I think they should be
>> fixed, and submit a patch to the list.
>>
>> Oh yeah, for purely hysterical reasons, I'm working with the 2.6.37.6
>> kernel from the stock balloonboard tree, if that makes any difference.
>>
>> --wpd
>>
>> _______________________________________________
>> Balloon mailing list
>> Balloon@balloonboard.org
>> http://balloonboard.org/mailman/listinfo/balloon
>
>