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

[Marc Zyngier]

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...
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/