On 02/29/2012 02:32 PM, Maxime Ripard wrote: > Hi everyone, > > I'm working on adding the support for the AT91SAM9M10G45-EK board from > Atmel for the at91_adc driver I previously posted, and I encounter some > weird issue here. > > When calling the iio_allocate_trigger > (http://lxr.free-electrons.com/source/drivers/staging/iio/industrialio-trigger.c?a=arm#L421) > from my driver on the G45, it returns ENOMEM, while on the > AT91SAM9G20-EK board, it works perfectly. > > Digging a bit into it, it seems that the call to irq_alloc_descs is > returning the error (the value of CONFIG_IIO_CONSUMERS_PER_TRIGGER is 2 > in my configuration, which seems pretty reasonable and is the default > value anyway), which is itself getting that return value from > irq_expand_nr_irqs. > > Here, I'm left confused, I don't know this part of the kernel anymore, > and most importantly, it seems to be pretty-much arch-independant, while > the nature of my issue seems really platform-dependant. > > Do you have any clue of what's going on here ? We ran into this originally on the pxa as well. My guess is that nr_irqs is not set high enough for that particular board. Looking back I can find some mention of a nasty bit of code that just adds a bit of padding but I can't find it now. Anyhow, you probably have a line somewhere in the kernel log saying something like: [ 0.000000] NR_IRQS:288 nr_irqs:296 296 NR_IRQS is typically the number of the SoC nr_irqs should be large enough to accomodate those provided by other peripherals. I also have a vague recollection that the problem goes away entirely with sparse irqs? Michael, you commented on this issue originally, can you remember any more details than me? (It seemed like I wrote plenty at the time but I can't for the life of me fill in the missing details!) -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
