On Tue, Aug 14, 2012 at 1:12 PM, Thierry Reding
<thierry.reding@xxxxxxxxxxxxxxxxx> wrote:
> On Thu, Jul 26, 2012 at 09:55:12PM +0200, Thierry Reding wrote:
>> diff --git a/arch/arm/boot/dts/tegra20.dtsi b/arch/arm/boot/dts/tegra20.dtsi
>> index a094c97..c886dff 100644
>> --- a/arch/arm/boot/dts/tegra20.dtsi
>> +++ b/arch/arm/boot/dts/tegra20.dtsi
>> @@ -199,6 +199,68 @@
>> #size-cells = <0>;
>> };
>>
>> + pcie-controller {
>> + compatible = "nvidia,tegra20-pcie";
>> + reg = <0x80003000 0x00000800 /* PADS registers */
>> + 0x80003800 0x00000200 /* AFI registers */
>> + 0x81000000 0x01000000 /* configuration space */
>> + 0x90000000 0x10000000>; /* extended configuration space */
>> + interrupts = <0 98 0x04 /* controller interrupt */
>> + 0 99 0x04>; /* MSI interrupt */
>> + status = "disabled";
>> +
>> + ranges = <0 0 0 0x80000000 0x00001000 /* root port 0 */
>> + 0 1 0 0x81000000 0x00800000 /* port 0 config space */
>> + 0 2 0 0x90000000 0x08000000 /* port 0 ext config space */
>> + 0 3 0 0x82000000 0x00010000 /* port 0 downstream I/O */
>> + 0 4 0 0xa0000000 0x08000000 /* port 0 non-prefetchable memory */
>> + 0 5 0 0xb0000000 0x08000000 /* port 0 prefetchable memory */
>> +
>> + 1 0 0 0x80001000 0x00001000 /* root port 1 */
>> + 1 1 0 0x81800000 0x00800000 /* port 1 config space */
>> + 1 2 0 0x98000000 0x08000000 /* port 1 ext config space */
>> + 1 3 0 0x82010000 0x00010000 /* port 1 downstream I/O */
>> + 1 4 0 0xa8000000 0x08000000 /* port 1 non-prefetchable memory */
>> + 1 5 0 0xb8000000 0x08000000>; /* port 1 prefetchable memory */
>
> I've been thinking about this some more. The translations for both the
> regular and extended configuration spaces are configured in the top-
> level PCIe controller. It is therefore wrong how they are passed to the
> PCI host bridges via the ranges property.
>
> I remember Mitch saying that it should be passed down to the children
> because it is partitioned among them, but since the layout is compatible
> with ECAM, the partitioning isn't as simple as what's in the tree. In
> fact the partitions will be dependent on the number of devices attached
> to the host bridges.
I don't understand this last bit about the number of devices attached
to the host bridges. Logically, the host bridge has a bus number
aperture that you can know up front, even before you know anything
about what devices are below it. On x86, for example, the ACPI _CRS
method has something like "[bus 00-7f]" in it, which means that any
buses in that range are below this bridge. That doesn't tell us
anything about which buses actually have devices on them, of course;
it's just analogous to the secondary and subordinate bus number
registers in a P2P bridge.
>> +
>> + #address-cells = <3>;
>> + #size-cells = <1>;
>> +
>> + pci@0 {
>> + device_type = "pciex";
>> + reg = <0 0 0 0x1000>;
>> + status = "disabled";
>> +
>> + #address-cells = <3>;
>> + #size-cells = <2>;
>> +
>> + ranges = <0x80000000 0 0 0 1 0 0 0x00800000 /* config space */
>> + 0x90000000 0 0 0 2 0 0 0x08000000 /* ext config space */
>> + 0x81000000 0 0 0 3 0 0 0x00010000 /* I/O */
>> + 0x82000000 0 0 0 4 0 0 0x08000000 /* non-prefetchable memory */
>> + 0xc2000000 0 0 0 5 0 0 0x08000000>; /* prefetchable memory */
>> +
>> + nvidia,num-lanes = <2>;
>> + };
>> +
>> + pci@1 {
>> + device_type = "pciex";
>> + reg = <1 0 0 0x1000>;
>> + status = "disabled";
>> +
>> + #address-cells = <3>;
>> + #size-cells = <2>;
>> +
>> + ranges = <0x80000000 0 0 1 1 0 0 0x00800000 /* config space */
>> + 0x90000000 0 0 1 2 0 0 0x08000000 /* ext config space */
>> + 0x81000000 0 0 1 3 0 0 0x00010000 /* I/O */
>> + 0x82000000 0 0 1 4 0 0 0x08000000 /* non-prefetchable memory */
>> + 0xc2000000 0 0 1 5 0 0 0x08000000>; /* prefetchable memory */
>> +
>> + nvidia,num-lanes = <2>;
>> + };
>> + };
>
> The same is true for the ranges properties of the PCI host bridge nodes.
> Which part of the configuration spaces maps to the children of the
> respective host bridge depends on the actual device hierarchy.
>
> Would it be possible to alternatively pass the complete range to the
> children without further partitioning?
>
> The driver doesn't actually care about the ranges property and only uses
> the values specified in the reg property of the pcie-controller node.
>
> Thierry
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