Majun,

On Tue, 13 Oct 2015, majun (F) wrote:

? 2015/10/12 0:45, Thomas Gleixner ??:

quoted

So now in the mbigen case this looks like this:

    [MSI-BUS] ----- [MBIGEN]<-------------------[Device interrupt]

Again, you have a 'wire' from the device to the MSI unit (MBIGEN) and
we do not care about that 'wire' either. What we care about is how we
find the MSI (mbigen) configuration registers for a particular
device. So we need a DT/ACPI entry which describes those configuration
registers and whatever supplementary information is required. That
will make the mbigen driver extremly simple.

According to your suggestions, I tried to make the hardware structure likes below:

device(8250 uart) -> mbigne -> ITS-pMSI --> ITS --> GIC

I'm not sure whether mbigen should be connected to ITS-pMSI (I assume
you mean ITS-PCI-MSI).

mbigen is a seperate MSI domain, so it should connect to ITS, but I
leave that to Marc.
 

And  8250 uart dts node is:

 8250_uart {
	compatible = "xxx";
	msi-parent = < &mbigen>;
	config_addr = <xxxxx> ; /* configuration register */
	interrupts = <x>;
	interrupt-parent = ?
}

My question is what's the interrupt-parent should be?

There is no interrupt parent for 8250_uart. Why would you want that?
I'm really not a DT expert, but I think you want something like this:

  8250_uart {
 	compatible = "xxx";
 	msi-parent = < &mbigen_node5>;
 	interrupt-map = <&mbigen5 0>;
  };

and then have

  mbigen_node5 {
  	...
	reg = <....>;
  };

So the other devices which are connected to mbigen_node5 have the same
msi-parent. But then again, please discuss that with Marc and the DT
wizards.

Thanks,

	tglx