On Mon, Mar 14, 2016 at 10:28:11PM -0400, Sinan Kaya wrote:
> On 3/14/2016 9:48 PM, Bjorn Helgaas wrote:
>
> Yes. I was talking about PCIe on ARM64.
>
> > If you go to Fry's and buy a conventional PCI card, it is going to
> > pull INTA# low to assert an interrupt. It doesn't matter whether you
> > put it in an x86 system or an arm64 system.
>
> I don't see INTA# of the PCIe card at the system level. The PCIe wire
> interrupt gets converted to the system level interrupt by the PCIe controller.
That's why I said *conventional PCI*. If you have a conventional PCI
device below either a conventional PCI host controller or a PCIe-to-PCI
bridge, there are real INTx wires, not virtual wires, and they are
level/low. But I think you pointed out the key below (that the
Interrupt resource in a PNP0C0F device encodes the trigger type).
> >> > I pasted the code here again. It looks like you want to validate that
> >> > PCI interrupts are always level low.
> > I don't really care whether PCI interrupts are always level low. What
> > matters is that the PCI interrupt line matches the configuration of
> > the interrupt controller input.
> >
>
> Agreed. But the interrupt controller configuration is system specific. How would
> you check interrupt line against what the interrupt controller requires
> on each architecture as this is common code?
>
>
> > If the PCI interrupt can be a different type, e.g., level high, and
> > there's a way to discover that, we can check that against the
> > interrupt controller configuration.
> >
> > This is all in the context of conventional PCI, and we're probably
> > talking about arm64 PCIe systems, not conventional PCI.
>
> INTx interrupts are TLP messages on PCIe as you already know. There is no INTA
> interrupt wire.
Yes, that's why I mentioned PCIe sec 2.2.8.1 below.
> "6.1.2. PCI Compatible INTx Emulation" section of the PCIe spec describes
> INTx emulation on PCIe.
> ...
>
> > I'm not sure what an Interrupt Link device means in PCIe. I suppose it would have
> > to connect an INTx virtual wire to a system interrupt? The PCIe spec
> > says this sort of mapping is system implementation specific (r3.0, sec
> > 2.2.8.1).
>
> The INTx messages are converted to the system interrupt by the PCIe controller.
> The interrupt type between the PCIe controller and the ARM GIC interrupt
> controller is dictated by the ARM GIC Interrupt Controller Specification for
> ARM64.
>
> Here is what ACPI table looks like for reference
>
> Name(_PRT, Package(){
> Package(){0x0FFFF, 0, \_SB.LN0A, 0}, // Slot 0, INTA
> Package(){0x0FFFF, 1, \_SB.LN0B, 0}, // Slot 0, INTB
> Package(){0x0FFFF, 2, \_SB.LN0C, 0}, // Slot 0, INTC
> Package(){0x0FFFF, 3, \_SB.LN0D, 0} // Slot 0, INTD
> })
>
> Device(LN0A){
> Name(_HID, EISAID("PNP0C0F")) // PCI interrupt link
> Name(_UID, 1)
> Name(_PRS, ResourceTemplate(){
> Interrupt(ResourceProducer, Level, ActiveHigh, Exclusive, , ,) {0x123}
> })
I forgot that the link already include the trigger mode in it. Maybe we
can check for that instead of assuming level/low.
Bjorn
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