Re: [PATCH v5 3/3] pci, pci-thunder-ecam: Add driver for ThunderX-pass1 on-chip devices

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 




On 02/08/2016 01:12 PM, Rob Herring wrote:
On Mon, Feb 8, 2016 at 2:47 PM, David Daney <ddaney@xxxxxxxxxxxxxxxxxx> wrote:
On 02/08/2016 11:56 AM, Rob Herring wrote:

On Fri, Feb 05, 2016 at 03:41:15PM -0800, David Daney wrote:

From: David Daney <david.daney@xxxxxxxxxx>

[...]

+Properties of the host controller node that differ from
+host-generic-pci.txt:
+
+- compatible     : Must be "cavium,pci-host-thunder-ecam"
+
+Example:
+
+       pci@84b0,00000000 {


Drop the comma,


OK...

and the node name should be "pcie".


Why pcie?

There are no PCIe devices or buses reachable from this type of root complex.
There are however many PCI devices.

I thought ECAM is a PCIe thing. If not, then nevermind.


Well, Enhanced Configuration Access Mechanism (ECAM) is defined the the PCI Express(R) base Specification, but it just defines a standard layout of address bits to memory map config space operations. Since the PCI config space is a sub set of the PCIe config space, ECAM can also be used in PCI systems.

Really, it is a bit of a gray area here as we don't have any bridges to PCIe buses and there are multiple devices residing on each bus, so from that point of view it cannot be PCIe. There are, however, devices that implement the PCI Express Capability structure, so does that make it PCIe? It is not clear what the specifications demand here.

I choose to call it "pci" as it lacks much of what it means to be PCIe, and also you cannot plug things into it.

David Daney




Rob


--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html



[Index of Archives]     [Device Tree Compilter]     [Device Tree Spec]     [Linux Driver Backports]     [Video for Linux]     [Linux USB Devel]     [Linux PCI Devel]     [Linux Audio Users]     [Linux Kernel]     [Linux SCSI]     [XFree86]     [Yosemite Backpacking]
  Powered by Linux