Messages in this thread | | | Date | Mon, 24 Jul 2023 11:18:42 -0700 | Subject | Re: [PATCH V10 2/5] PCI: Create device tree node for bridge | From | Lizhi Hou <> |
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On 7/18/23 11:15, Rob Herring wrote: > On Fri, Jun 30, 2023 at 12:25 PM Lizhi Hou <lizhi.hou@amd.com> wrote: >> >> On 6/29/23 16:52, Rob Herring wrote: >>>>> + rp[i].child_addr[0] = j; >>>>> + ret = of_changeset_add_empty_prop(ocs, np, "dynamic"); >>>> It seems slightly confusing to use a "dynamic" property here when we >>>> also have the OF_DYNAMIC dynamic flag above. I think they have >>>> different meanings, don't they? >>> Hum, what's the property for? It's new in this version. Any DT property >>> needs to be documented, but I don't see why we need it. >> This is mentioned in my previous reply for V9 >> >> https://lore.kernel.org/lkml/af9b6bb3-a98d-4fb6-b51e-b48bca61dada@amd.com/ >> >> As we discussed before, "interrupt-map" was intended to be used here. >> >> And after thinking it more, it may not work for the cases where ppnode >> >> is not dynamically generated and it does not have "interrupt-map". >> >> For example the IBM ppc system, its device tree has nodes for pci bridge >> >> and it does not have "interrupt-map". > How do you know? I ask because usually the only way I have visibility > there is when I break something. In traditional OpenFirmware, which > IBM PPC is, all PCI devices have a DT node because it's the firmware > telling the OS "these are the devices I discovered and this is how I > configured them".
I configured a ppc VM and added a bridge to the VM
qemu-system-ppc -L pc-bios -boot c -prom-env "boot-device=hd:,\yaboot" -prom-env "boot-args=conf=hd:,\yaboot.conf" -M mac99 -m 1024 -hda debian10.qcow2 -nographic -device pci-bridge,chassis_nr=1,id=pci.9
# ls /proc/device-tree/pci\@f2000000/pci1b36\,1\@f/ 66mhz-capable class-code fast-back-to-back min-grant vendor-id assigned-addresses device-id interrupts name bus-range devsel-speed linux,phandle reg cache-line-size ethernet@1 max-latency revision-id
The bridge node does not have 'interrupt-map'. That is why I concerned for using 'interrupt-map'.
To further debugging on if it really breaks anything, I added a nic device under bridge. Even without my patch, it is failed anyway.
[ 0.086586] pci 0000:01:01.0: of_irq_parse_pci: failed with rc=-22
So I setup another power10 VM and see the 'interrupt-map' is created for pci bridge. And the nic device under bridge works fine.
Maybe using 'interrupt-map' will not break anything in the real world. I will re-create a patchset which uses 'interrupt-map' (like V9) and checks it only when CONFIG_PCI_DYNAMIC_OF_NODES is turned on.
Thanks,
Lizhi
> >> Based on previous discussions, OF_DYNAMIC should not be used here. > For the same reasons, I don't think the behavior should change based > on being dynamic. Now maybe the behavior when it's an ACPI system with > DT overlays has to change, but that's a problem for later. I don't yet > know if we'd handle that here somehow or elsewhere so that this node > looks like a normal DT system. > > This should all work the same whether we've generated the nodes or > they were already present in the FDT when we booted. > >> So I think adding "dynamic" might be a way to identify the dynamically >> >> added node. Or we can introduce a new flag e.g OF_IRQ_SWIZZLING. > I hope not. The flags tend to be hacks. > > Rob
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