Messages in this thread | | | From | Jayachandran C <> | Date | Mon, 2 May 2016 18:56:13 +0530 | Subject | Re: [PATCH V6 02/13] pci, acpi: Provide generic way to assign bus domain number. |
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On Mon, May 2, 2016 at 6:13 PM, Tomasz Nowicki <tn@semihalf.com> wrote: > On 04/27/2016 01:17 PM, Lorenzo Pieralisi wrote: >> >> On Tue, Apr 26, 2016 at 09:26:49PM -0500, Bjorn Helgaas wrote: >>> >>> On Fri, Apr 15, 2016 at 07:06:37PM +0200, Tomasz Nowicki wrote: > > [...] > >>> +int acpi_pci_bus_domain_nr(struct device *parent) >>> +{ >>> + struct acpi_device *acpi_dev = to_acpi_device(parent); >>> + unsigned long long segment = 0; >>> + acpi_status status; >>> + >>> + /* >>> + * If _SEG method does not exist, following ACPI spec (6.5.6) >>> + * all PCI buses belong to domain 0. >>> + */ >>> + status = acpi_evaluate_integer(acpi_dev->handle, >>> METHOD_NAME__SEG, NULL, >>> + &segment); >>> We already have code in acpi_pci_root_add() to evaluate _SEG. We >>> don't want to evaluate it *twice*, do we? >>> >>> I was sort of expecting that if you added it here, we'd remove the >>> existing call, but it looks like you're keeping both? >> >> We can't remove the existing call, since it is used on X86 and IA64 >> to store the segment number that, in the process, is used in their >> pci_domain_nr() arch specific callback to retrieve the domain nr. >> >> On ARM64, that selects PCI_DOMAINS_GENERIC, we have to find a way >> to retrieve the domain number that is not arch dependent, since >> this is generic code, we can't rely on any bus->sysdata format (unless >> we do something like JC did below), therefore the only way is to call >> the _SEG method *again* here, which also forced Tomasz to go through >> the ACPI_COMPANION setting song and dance and pass the parent pointer >> to pci_create_root_bus() (see patch 1), which BTW is a source of >> trouble on its own as you noticed. > > What trouble in patch 1 do you mean? I may miss something. > > I agree that patch 1 is not necessary if we decide to use sysdata or rework > root bus scanning to move domain to host bridge. Nevertheless, patch 1 is > still a cleanup IMO.
In this case, getting the domain should be trivial since the ACPI companion on parent is already set, this should work
int acpi_pci_bus_domain_nr(struct device *parent) { struct acpi_device *acpi_dev = to_acpi_device(parent); struct acpi_pci_root *root = acpi_dev->driver_data;
return root->segment; }
Or am I missing something here?
JC.
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