[PATCH v3 2/2] dt-bindings: pcie: Add documentation for Mediatek PCIe

[Ryder Lee]

On Thu, 2017-05-11 at 09:17 +0200, Arnd Bergmann wrote:
> On Thu, May 11, 2017 at 4:44 AM, Ryder Lee <ryder.lee at mediatek.com> wrote:
> > On Wed, 2017-05-10 at 12:01 +0200, Arnd Bergmann wrote:
> >> On Wed, May 10, 2017 at 11:31 AM, Ryder Lee <ryder.lee at mediatek.com> wrote:
> >> > On Wed, 2017-05-10 at 10:08 +0200, Arnd Bergmann wrote:
> 
> >> >> > +Required properties:
> >> >> > +- device_type: Must be "pci"
> >> >> > +- assigned-addresses: Address and size of the port configuration registers
> >> >> > +- reg: Only the first four bytes are used to refer to the correct bus number
> >> >> > +  and device number.
> >> >> > +- #address-cells: Must be 3
> >> >> > +- #size-cells: Must be 2
> >> >> > +- #interrupt-cells: Must be 1
> >> >> > +- interrupt-map-mask and interrupt-map: Standard PCI IRQ mapping properties
> >> >> > +  Please refer to the standard PCI bus binding document for a more detailed
> >> >> > +  explanation.
> >> >>
> >> >> Child nodes do not normally have interrupt-map properties. Isn't this
> >> >> already covered by the interrupt-map in the parent?
> >> >>
> >> >
> >> > I have one Intel 4 port ethernet card(0000:00:01) and MTK WLAN card
> >> > (0000:00:02), probe message looks good to me.
> >> >
> >> > pci 0000:00:01.0: fixup irq: got 224
> >> > pci 0000:00:01.0: assigning IRQ 224
> >> > pci 0000:00:02.0: fixup irq: got 225
> >> > pci 0000:00:02.0: assigning IRQ 225
> >> >
> >> > pci 0000:01:00.0: fixup irq: got 224
> >> > pci 0000:01:00.0: assigning IRQ 224
> >> > pci 0000:01:00.1: fixup irq: got 224
> >> > pci 0000:01:00.1: assigning IRQ 224
> >> > pci 0000:01:00.2: fixup irq: got 224
> >> > pci 0000:01:00.2: assigning IRQ 224
> >> > pci 0000:01:00.3: fixup irq: got 224
> >> > pci 0000:01:00.3: assigning IRQ 224
> >> >
> >> > pci 0000:02:00.0: fixup irq: got 225
> >> > pci 0000:02:00.0: assigning IRQ 225
> >> >
> >> >
> >> > But child nodes without interrupt-map properties:
> >> > It seems incorrect.
> >> >
> >> > pci 0000:00:01.0: fixup irq: got 224
> >> > pci 0000:00:01.0: assigning IRQ 224
> >> > pci 0000:00:02.0: fixup irq: got 225
> >> > pci 0000:00:02.0: assigning IRQ 225
> >> >
> >> > pci 0000:01:00.0: fixup irq: got 223
> >> > pci 0000:01:00.0: assigning IRQ 223
> >>
> >> Not entirely sure what happens here, but I guess the problem
> >> is that the 'reg' portion of the parent interrupt-map refers to
> >> the port devices, not the devices attached the devices behind
> >> them.
> >
> > I agree with you. That's why I need additional interrupt-map properties
> > to resolve IRQ correctly for the devices behind root ports.
> >
> > Not sure whether other platforms have similar case like me here.
> 
> I think it's just a bug in this specific chip where the HW designers
> wired the IRQs in a nonstandard way.
> 
> However, you really should not need the interrupt-map properties
> in the child nodes, just change the address part in the parent
> interrupt-map. Specifically, the 'bus' portion of the device address
> in the interrupt-map would have to be nonzero to refer to
> child devices.

This is what I modify for the parent node and remove interrupt-map
properties from child..

interrupt-map-mask = <0xff800 0 0 0>;
interrupt-map = <0x0000 0 0 0 &gic GIC_SPI 193 IRQ_TYPE_NONE>,
		 <0x0800 0 0 0 &gic GIC_SPI 194 IRQ_TYPE_NONE>,
		 <0x1000 0 0 0 &gic GIC_SPI 195 IRQ_TYPE_NONE>,

		 /* workaround here*/
		 <0x10000 0 0 0 &gic GIC_SPI 193 IRQ_TYPE_NONE>,
		 <0x20000 0 0 0 &gic GIC_SPI 194 IRQ_TYPE_NONE>,
	     <0x30000 0 0 0 &gic GIC_SPI 195 IRQ_TYPE_NONE>;

It works well. But how could we handle the situation if root port0
status = "disabled" ? I think we cannot assign child bus number
dynamically from binding.

> >> On a related note, I see that you still list
> >>
> >> > +- interrupts: Three interrupt outputs of the controller. Must contain an
> >> > +  entry for each entry in the interrupt-names property.
> >> > +- interrupt-names: Must include the following names
> >> > +  - "pcie-int0"
> >> > +  - "pcie-int1"
> >> > +  - "pcie-int2"
> >>
> >> This seems to be an artifact from the older version and should be
> >> removed as the driver correctly ignores the properties now.
> >
> > Actually, everything works fine without these properties however when it
> > loads we see a few weird error message:
> >
> > pcieport 0000:00:01.0: Signaling PME with IRQ 232
> > pcieport 0000:00:02.0: enabling device (0140 -> 0142)
> > pcieport 0000:00:02.0: enabling bus mastering
> > irq 232: nobody cared (try booting with the "irqpoll" option)
> > ...
> > [<c03f6be4>] (pcie_pme_probe) from [<c03f47b8>] (pcie_port_probe_service
> > +0x44/0x6c)
> > (pcie_port_probe_service) from [<c0454cf8>] (driver_probe_device
> > +0x280/0x470)
> > ...
> > (pcie_port_device_register) from [<c03f51a0>] (pcie_portdrv_probe
> > +0x3c/0xb4)
> > (pcie_portdrv_probe) from [<c03e7acc>] (pci_device_probe+0x98/0xfc)
> > (pci_device_probe) from [<c0454cf8>] (driver_probe_device+0x280/0x470)
> > handlers:
> > [<c03f68b0>] pcie_pme_irq
> > Disabling IRQ #233
> >
> > I haven't dig it out yet, but just keep them here to solve that.
> 
> Something is going very wrong if adding the properties helps. I can't
> think of what that is, but we have to find out before the binding can
> be merged.

Not really understand PME service. But I will find the reason here.