Re: [PATCH V3 20/21] pci, acpi: Match PCI config space accessors against platfrom specific quirks.

[Tomasz Nowicki]

On 19.01.2016 02:49, liudongdong (C) wrote:
> Hi Tomasz, Mark
>
> å 2016/1/18 20:41, Tomasz Nowicki åé:
> > On 14.01.2016 16:36, Mark Salter wrote:
> > > > +extern struct pci_mcfg_fixup __start_acpi_mcfg_fixups[];
> > > > >+extern struct pci_mcfg_fixup __end_acpi_mcfg_fixups[];
> > > > >+
> > > > >+static struct pci_ops *pci_mcfg_check_quirks(struct acpi_pci_root
> > > > *root)
> > > > >+{
> > > > >+    struct pci_mcfg_fixup *f;
> > > > >+    int bus_num = root->secondary.start;
> > > > >+    int domain = root->segment;
> > > > >+
> > > > >+    /*
> > > > >+     * First match against PCI topology <domain:bus> then use DMI or
> > > > >+     * custom match handler.
> > > > >+     */
> > > > >+    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) &&
> > > > >+            (f->system ? dmi_check_system(f->system) : 0 ||
> > > > >+             f->match ? f->match(f, root) : 0))
> > > > >+            return f->ops;
> > > I think this would be better as:
> > >
> > >             (f->system ? dmi_check_system(f->system) : 1 &&
> > >              f->match ? f->match(f, root) : 1))
> > >             return f->ops;
> > >
> > > Otherwise, one has to call dmi_check_system() from f->match() if
> > > access to root is needed.
>
> Non-DMI, we need not to call dmi_check_system() from f->match(),
> we can use _HID to decide to hook the pci_ops or not.

Sorry, but I dont understand your point. Can you elaborate?

With Mark modification, you can use the following cases to identify 
platform:
1. DMI only
2. f->match() only (_HID can be used there)
3. DMI and f->match()

DMI used to be very convenient way to recognise platform, sometimes it 
is not enough, hence f->match() alternative.

Tomasz