[PATCH v3 24/25] irq_domain: remove "hint" when allocating irq numbers

On Wed, Feb 15, 2012 at 01:21:45PM -0700, Grant Likely wrote:

On Wed, Feb 15, 2012 at 04:04:28PM +0100, Nicolas Ferre wrote:

quoted

On 02/07/2012 07:07 PM, Nicolas Ferre :

quoted

On 01/27/2012 10:36 PM, Grant Likely :

quoted

The 'hint' used to try and line up irq numbers with hw irq numbers is
rather a hack and not very useful.  Now that /proc/interrupts also outputs
the hwirq number, it is even less useful to keep around the 'hint' heuristic.

This patch removes it.

Grant,

While trying your patch series in conjunction with Rob one, I do not
find this patch in your irqdomain/next branch (and a couple of others).
Can you tell me if this v3 series is available as a git tree?

I am still interested by patch 24-25 of this series but still cannot
find them in your irqdomain/next branch:
Are they also expected to join the 3.4 merge window material?

I've held off on putting them in irqdomain/next because they are a bit more
risky than the other patches, and I want an explicit ack from Ben for patches
24 & 25.  However, that shouldn't really cause any issues since the changes
in 24 & 25 don't impact the irq_domain functionality or API.  They are just
optimizations.

I'm seeing that patch 24 does impact on irq_domain functionality
a little bit.  On next tree which has no this patch yet,
irq_create_mapping can reasonably create virq in range 1..15, while
irq_find_mapping will only try to find the virq from 16
(NUM_ISA_INTERRUPTS).  This will result in that any hwirq that is < 16
gets multiple entries in the mapping table with different virq numbers
mapped to the same one hwirq.

That's why I have to apply patch #24 (with one line change below) on
top of next tree to get my imx irqdomain series work properly.

@@ -371,7 +371,7 @@ unsigned int irq_create_mapping(struct irq_domain *domain,
                return irq_domain_legacy_revmap(domain, hwirq);
 
        /* Allocate a virtual interrupt number */
-       virq = irq_alloc_desc(0);
+       virq = irq_alloc_desc_from(1, 0);
        if (!virq) {
                pr_debug("irq: -> virq allocation failed\n");
                return 0;

I need this line of change, because the first call on irq_alloc_desc
will always return 0 to virq and in turn irq_create_mapping fails.
On imx, that's the mapping for timer irq.  Hence, the system will hang
there due to irq mapping failure.

-- 
Regards,
Shawn