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Re: [Xen-devel] [PATCH for-4.5 7/8] xen/irq: Handle multiple action per IRQ

Hi Ian,

On 03/18/2014 09:33 AM, Ian Campbell wrote:
> On Mon, 2014-03-17 at 21:05 +0000, Julien Grall wrote:
>> For instance for the SMMU on midway, the device tree bindings is:
>>                smmu_sata: smmu@9,20180000 {
>>                        compatible = "arm,mmu-400";
>>                        reg = <0x9 0x20180000 0x10000>;
>>                        mmu-masters = <&sata 0 1 2 3 4 5 6 7 8 9>;
>>                        #global-interrupts = <1>;
>>                        interrupts = <0 114 4 0 114 4>;
>>                        calxeda,smmu-secure-config-access;
>>                        arm,smmu-isolate-devices;
>>               };
>> As you can see the same interrupts is used twice:
> Is that actually valid in device tree? Or is this a quirk of the midway
> DT?

Yes it's valid. The interrupts property for the SMMU is described as:

"Interrupt list, with the first #global-irqs entries corresponding to
the global interrupts and any following entries corresponding to context
interrupts, specified in order of their indexing by the SMMU.

For SMMUv2 implementations, there must be exactly one interrupt per
context bank. In the case of a single, combined interrupt, it must be
listed multiple times."

On midway there is only one IRQ with is used for both context interrupt
and global interrupt. As it's the only platform on Linux with SMMU
support in the device tree, we don't know if every platform will have
the same behavior.


Julien Grall

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