[PATCH] ARM: OMAP: irqs: Fix NR_IRQS value to handle PRCM interrupts

[PATCH] ARM: OMAP: irqs: Fix NR_IRQS value to handle PRCM interrupts

[Cousson, Benoit]

The following commit: 2f31b51659c2d8315ea2888ba5b93076febe672b
Author: Tero Kristo <t-kristo@ti.com>
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

Fix that by adding 64 more interrupts for OMAP2PLUS config.

Signed-off-by: Benoit Cousson <b-cousson@ti.com>
Cc: Tero Kristo <t-kristo@ti.com>
---
Tony,

This patch should probably go for the next -rc if possible.

Thanks,
Benoit

 arch/arm/plat-omap/include/plat/irqs.h |   10 +++++++++-
 1 files changed, 9 insertions(+), 1 deletions(-)

diff --git a/arch/arm/plat-omap/include/plat/irqs.h b/arch/arm/plat-omap/include/plat/irqs.h
index 2efd645..37bbbbb 100644
--- a/arch/arm/plat-omap/include/plat/irqs.h
+++ b/arch/arm/plat-omap/include/plat/irqs.h
@@ -428,8 +428,16 @@
 #define OMAP_GPMC_NR_IRQS	8
 #define OMAP_GPMC_IRQ_END	(OMAP_GPMC_IRQ_BASE + OMAP_GPMC_NR_IRQS)
 
+/* PRCM IRQ handler */
+#ifdef CONFIG_ARCH_OMAP2PLUS
+#define OMAP_PRCM_IRQ_BASE	(OMAP_GPMC_IRQ_END)
+#define OMAP_PRCM_NR_IRQS	64
+#define OMAP_PRCM_IRQ_END	(OMAP_PRCM_IRQ_BASE + OMAP_PRCM_NR_IRQS)
+#else
+#define OMAP_PRCM_IRQ_END	OMAP_GPMC_IRQ_END
+#endif
 
-#define NR_IRQS			OMAP_GPMC_IRQ_END
+#define NR_IRQS			OMAP_PRCM_IRQ_END
 
 #define OMAP_IRQ_BIT(irq)	(1 << ((irq) % 32))
 
-- 
1.7.0.4

[PATCH] ARM: OMAP: irqs: Fix NR_IRQS value to handle PRCM interrupts

[Russell King - ARM Linux]

On Tue, Feb 28, 2012 at 02:10:09PM +0100, Cousson, Benoit wrote:
> The following commit: 2f31b51659c2d8315ea2888ba5b93076febe672b
> Author: Tero Kristo <t-kristo@ti.com>
> 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.

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.

[PATCH] ARM: OMAP: irqs: Fix NR_IRQS value to handle PRCM interrupts

[Cousson, Benoit]

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@ti.com>
>> 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

[PATCH] ARM: OMAP: irqs: Fix NR_IRQS value to handle PRCM interrupts

[Russell King - ARM Linux]

On Tue, Feb 28, 2012 at 09:32:28PM +0100, Cousson, Benoit wrote:
> 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@ti.com>
>>> 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.

One thing I didn't consider is that the GIC has been converted to
sparse IRQ support, so enabling it on OMAP will make the irq_alloc_descs()
in there to fail if you try and keep it below NR_IRQS.

That rules out a piecemeal conversion, which rather sucks.

[PATCH] ARM: OMAP: irqs: Fix NR_IRQS value to handle PRCM interrupts

[Tony Lindgren]

* Cousson, Benoit <b-cousson@ti.com> [120228 04:38]:
> The following commit: 2f31b51659c2d8315ea2888ba5b93076febe672b
> Author: Tero Kristo <t-kristo@ti.com>
> 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
> 
> Fix that by adding 64 more interrupts for OMAP2PLUS config.
> 
> Signed-off-by: Benoit Cousson <b-cousson@ti.com>
> Cc: Tero Kristo <t-kristo@ti.com>
> ---
> Tony,
> 
> This patch should probably go for the next -rc if possible.

Thanks applying into fixes as it seems like the only available
fix right now.

Tony