Re: [PATCH v3 05/12] PCI: of_property: Assign PCI instead of CPU bus address to dynamic bridge nodes

Stanimir Varbanov
2024-11-07T11:51:41Z

Hi Mani,

On 11/6/24 16:35, Manivannan Sadhasivam wrote:
> On Mon, Nov 04, 2024 at 05:49:37PM -0600, Bjorn Helgaas wrote:
>> On Mon, Nov 04, 2024 at 08:35:21PM +0530, Manivannan Sadhasivam wrote:
>>> On Mon, Nov 04, 2024 at 09:54:57AM +0100, Andrea della Porta wrote:
>>>> On 22:39 Sat 02 Nov , Manivannan Sadhasivam wrote:
>>>>> On Mon, Oct 28, 2024 at 03:07:22PM +0100, Andrea della Porta wrote:
>>>>>> When populating "ranges" property for a PCI bridge, of_pci_prop_ranges()
>>>>>> incorrectly use the CPU bus address of the resource. Since this is a PCI-PCI
>>>>>> bridge, the window should instead be in PCI address space. Call
>>>>>> pci_bus_address() on the resource in order to obtain the PCI bus
>>>>>> address.
>>>>>
>>>>> of_pci_prop_ranges() could be called for PCI devices also (not just PCI
>>>>> bridges), right?
>>>>
>>>> Correct. Please note however that while the PCI-PCI bridge has the parent
>>>> address in CPU space, an endpoint device has it in PCI space: here we're
>>>> focusing on the bridge part. It probably used to work before since in many
>>>> cases the CPU and PCI address are the same, but it breaks down when they
>>>> differ.
>>>
>>> When you say 'focusing', you are specifically referring to the
>>> bridge part of this API I believe. But I don't see a check for the
>>> bridge in your change, which is what concerning me. Am I missing
>>> something?
>>
>> I think we want this change for all devices in the PCI address
>> domain, including PCI-PCI bridges and endpoints, don't we? All those
>> "ranges" addresses should be in the PCI domain.
>>
>
> Yeah, right. I was slightly confused by the commit message. Maybe including a
> sentence about how the change will work fine for endpoint devices would help.
> Also, why it went unnoticed till now (ie., both CPU and PCI addresses are same
> in many SoCs).

Most probably it is unnoticed because until now nobody has enabled
/selected CONFIG_PCI_DYNAMIC_OF_NODES ?

~Stan