[EXT] Re: [PATCH v3 3/4] dt-bindings: irqchip: imx mu work as msi controller

[Krzysztof Kozlowski]

On 25/07/2022 18:55, Frank Li wrote:

>>>> Not minItems but maxItems in general, but anyway you need to actually
>>>> list and describe the items (and then skip min/max)
>>> [Frank Li]
>>>       I am not sure format.  Any example?
>>>
>>> Reg:
>>>       Items:
>>>            - description:  a side register
>>>            - description: b side register
>>
>> Yes, but then explain what is A and B in bindings description.
> 
> [Frank Li]  How about "A(B) side base register address."
> Any other description need?  

In top-level description you have:
  "The MU also provides the ability for one processor to signal the
other processor using interrupts."

so maybe:
  "The MU also provides the ability for one processor (A side) to signal
the other processor (B side) using interrupts."

> 
>>
>> Why MU, which sits on A side needs to access other side (B) registers?
> 
> [Frank Li] MU work as MSI controller for PCI EP.  So driver need provide
> B side register to PCI EP by msi_msg.   PCI EP driver use this address to set
> PCI bar<n>.  Then PCI host can write this address to trigger PCIe EP side irq
> As doorbell. 
> 
> MU MSI driver also need A side register
> To get irq status.  So MU MSI need both side registers. 

OK.


Best regards,
Krzysztof