Hello,
I'm a newbie to devicetrees, and am trying to understand and create device tree
for a new powerpc platform. My questions:
1) For a PCI-PCI bridge that I'm representing like this:
pcie@2,3 {
vendor-id = <0x10b5>;
device-id = <0x8618>;
class-code = <0x060400>;
#size-cells = <2>;
#address-cells = <3>;
device_type = "pci";
bus-range = <0x20 0x2f>;
reg = <0x00021800 0x00000000 0x000000000 /* Cfg:2.3.0: */
0x00000000 0x00000000>;
ranges = <0x02000000 0x00000000 0xA0000000 /* Mem behind bridge:
0xA0000000 - 0xA03FFFFF */
0x02000000 0x00000000 0xA0000000
0x00000000 0x04000000>;
};
Is the above is only to _notify_ the kernel that this is how the firmware shall
be setting the PCI bridge (Thus firmware has obligation of setting it like this
before passing control to the kernel), and hence the kernel will merely take
note of it?
Or is the above telling the kernel that this is how the kernel should _setup_
the device (thus firmware does not set up the device, but rather the kernel use
this info to setup the device)?
2) For an PCI endpoint that I am representing like this:
xyz@20,0 {
vendor-id = ...
device-id = ...
class-code = <0x0880>;
compatible = ...
...
reg = <0x00200000 0x00000000 0x00000000 /* Cfg:20.0.0: */
0x00000000 0x00000000
0x02200010 0x00000000 0xA0000000 /* Mem:20.0.0:(Bar0)
64MB@0xA0000000 */
0x00000000 0x04000000>;
...
};
Does the above tell the kernel to _program_ the BAR0 register using the above
address? Or does it cause the kernel to assume that the BAR0 has been
programmed with this address?
3) Lastly, what is the difference in behavior when I select PCI_PROBE_NORMAL
over PCI_PROBE_DEVTREE?
Thanks,
Rajat
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