Hi Russell,
On 2/28/2012 3:36 PM, Russell King - ARM Linux wrote:
On Tue, Feb 28, 2012 at 02:10:09PM +0100, Cousson, Benoit wrote:
The following commit: 2f31b51659c2d8315ea2888ba5b93076febe672b
Author: Tero Kristo<t-kristo@xxxxxx>
Date: Fri Dec 16 14:37:00 2011 -0700
ARM: OMAP4: PRM: use PRCM interrupt handler
introduced the PRCM interrupt handler and thus the need
for 64 more interrupts. Since SPARSE_IRQ is still not fully
functional on OMAP, the NR_IRQS needs to be updated to avoid
the failure that happen during irq_alloc_descs call inside
the PRCM driver:
[ 0.208221] PRCM: failed to allocate irq descs: -12
Later the mux framework is then unable to request an IRQ from
the PRCM interrupt handler.
[ 1.802795] mux: Failed to setup hwmod io irq -22
This is fine for rc, but longer term...
Do any of these have hard-coded interrupt numbers associated with them?
If not, just enabling sparse IRQ will sort this out.
You're right, in that case, it does not depend on any hard-coded number.
As I tried to explain yesterday, there are two modes for IRQ allocation:
1. Without sparse IRQ enabled, irq_alloc_descs(-1, from, num, -1) will
allocate IRQs _within_ the existing from..NR_IRQS range, and will fail
if there is insufficient IRQs available.
2. With sparse IRQs enabled, irq_alloc_descs(-1, from, num, -1) will
allocate IRQs starting at max(from, NR_IRQS) and working upwards.
In either case, irq_alloc_descs(start, 0, num, -1) will allocate 'num'
IRQs at 'start' or fail if the range is already in use (and 0..NR_IRQS
is defined as 'being in use' when sparse IRQs are enabled.)
So, if the PRCM interrupts aren't statically assigned (the code suggests
that they aren't) then it's already sparse-IRQ compliant, and enabling
sparse IRQ support will mean that they will be allocated above NR_IRQS.
Therefore, I suggest rather than raising NR_IRQS, you instead enable
SPARSE_IRQ now so that anyone using the dynamic IRQ allocation can
benefit from sparse IRQ support without having to have a large NR_IRQS.
So, you don't have to wait until everything is converted to use
sparse IRQ. You just need to make sure that nothing uses
irq_alloc_descs(start, from, num, ...) where start< NR_IRQS, and
nothing using that requires statically defined IRQ numbering.
Yes, I fully agree, and that's still the plan. That's why I started
sending last week a bunch of cleanup for SPARSE_IRQ support.
Unfortunately, they might not be ready for 3.4 either, but I'm still
working on it.
Meanwhile, we need the current temporary fix.
I can emphasis the temporary duration on that patch in the changelog if
needed.
Thanks,
Benoit
--
To unsubscribe from this list: send the line "unsubscribe linux-omap" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
