[PATCH 4/4 V3] irqchip: gicv2m: Add support for multiple MSI for ARM64 GICv2m

Marc Zyngier
2014-08-01T14:51:50Z

Hi Suravee,

On 01/08/14 15:36, Suravee Suthikulanit wrote:
> On 7/30/2014 10:16 AM, Marc Zyngier wrote:
>> Why do we need this complexity at all? Is there any case where we'd want
>> to limit ourselves to a single vector for MSI?
>
> I think the ARM64 GICv2m should not be the limitation for the devices
> multiple MSI if there is no real hardware/design limitation.
>
>> arm64 is a new enough architecture so that we can expect all interrupt controllers to cope
>> with that.
>
> I am not sure if I understand this comment.
>
> We are not forcing all interrupt controllers for ARM64 to handle
> multi-MSI. They have the option to support if multi-MSI if they want
> to. I just think that we should not put the architectural limit here.

Let me be clearer: I think we should put the burden of *not* handling
multi-MSI on interrupt controllers. Here, you're making the
architectural default to be "I don't support multi-MSI", hence having to
override global vectors and such for well behaved MSI controllers like
GICv2m and GICv3 ITS.

Let's only support multi-MSI for the time being. If someone comes up
with a silly old MSI controller that can't deal with it, we'll address
the issue at that problem.

Thanks,

M.
--
Jazz is not dead. It just smells funny...