On Thursday, June 2, 2016 3:35:34 PM CEST Tomasz Nowicki wrote:

On 02.06.2016 14:32, Arnd Bergmann wrote:

quoted

On Thursday, June 2, 2016 2:07:43 PM CEST Tomasz Nowicki wrote:

quoted

On 02.06.2016 13:42, Arnd Bergmann wrote:

quoted

On Thursday, June 2, 2016 10:41:01 AM CEST Tomasz Nowicki wrote:

quoted

+struct pci_ecam_ops *pci_mcfg_get_ops(struct acpi_pci_root *root)
+{
+       int bus_num = root->secondary.start;
+       int domain = root->segment;
+       struct pci_cfg_fixup *f;
+
+       if (!mcfg_table)
+               return &pci_generic_ecam_ops;
+
+       /*
+        * Match against platform specific quirks and return corresponding
+        * CAM ops.
+        *
+        * First match against PCI topology <domain:bus> then use OEM ID and
+        * OEM revision from MCFG table standard header.
+        */
+       for (f = __start_acpi_mcfg_fixups; f < __end_acpi_mcfg_fixups; f++) {
+               if ((f->domain == domain || f->domain == PCI_MCFG_DOMAIN_ANY) &&
+                   (f->bus_num == bus_num || f->bus_num == PCI_MCFG_BUS_ANY) &&
+                   (!strncmp(f->oem_id, mcfg_table->header.oem_id,
+                             ACPI_OEM_ID_SIZE)) &&
+                   (f->oem_revision == mcfg_table->header.oem_revision))
+                       return f->ops;
+       }
+       /* No quirks, use ECAM */
+       return &pci_generic_ecam_ops;
+}
+
   int pci_mcfg_lookup(struct acpi_pci_root *root)

Can you explain the use of pci_ecam_ops instead of pci_ops here?

I wanted to get associated bus_shift and use it to setup configuration
region properly before calling pci_ecam_create. Please see next patch.

I see. It feels really odd to do it this way though, since having a
nonstandard bus_shift essentially means not using anything resembling
ECAM to start with.

I realize that a lot of the host bridges are not ECAM, but because
of this, it would be more logical to have their own pci_ops instead
of pci_ecam_ops.

Well, we have bus_shift there to express bus shift differentiation. So I 
would say we should change just structure name to prevent misunderstanding.

I'm not really convinced here. We use the bus_shift for two
completely different things in the end: for sizing the MMIO window
that gets mapped by ACPI and for the pci_ecam_map_bus() function
that isn't actually used for the typical fixups that override the
pci_ops.

I see now that this sneaks in an .init callback for the quirk
through the backdoor, by adding it to the pci_ecam_ops. I think
that is not good: if the idea is to have the config space access
be adapted to various quirks that is one thing, but if we actually
need a function to be called for the quirk we should do just that
and have it be obvious. That function can then override the
pci_ops.

	Arnd