Re: RFC: [PATCH 1/3] Enhance platform support for PCI

[Manish Jaggi <mjaggi@caviumnetworks.com>]

On Tuesday 17 March 2015 12:58 PM, Jan Beulich wrote:
>>>> On 17.03.15 at 06:26, <mjaggi@caviumnetworks.com> wrote:
>> In drivers/xen/pci.c on notification BUS_NOTIFY_ADD_DEVICE dom0 issues a
>> hypercall to inform xen that a new pci device has been added.
>> If we were to inform xen about a new pci bus that is added there are  2 ways
>> a) Issue the hypercall from drivers/pci/probe.c
>> b) When a new device is found (BUS_NOTIFY_ADD_DEVICE) issue
>> PHYSDEVOP_pci_device_add hypercall to xen, if xen does not finds that
>> segment number (s_bdf), it will return an error
>> SEG_NO_NOT_FOUND. After that the linux xen code could issue the
>> PHYSDEVOP_pci_host_bridge_add hypercall.
>>
>> I think (b) can be done with minimal code changes. What do you think ?
> I'm pretty sure (a) would even be refused by the maintainers, unless
> there already is a notification being sent. As to (b) - kernel code could
> keep track of which segment/bus pairs it informed Xen about, and
> hence wouldn't even need to wait for an error to be returned from
> the device-add request (which in your proposal would need to be re-
> issued after the host-bridge-add).
Have a query on the CFG space address to be passed as hypercall parameter.
The of_pci_get_host_bridge_resource only parses the ranges property and 
not reg.
reg property has the CFG space address, which is usually stored in 
private pci host controller driver structures.

so pci_dev 's parent pci_bus would not have that info.
One way is to add a method in struct pci_ops but not sure it will be 
accepted or not.
> Jan
>
>
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