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SubjectRe: [PATCH V3 20/21] pci, acpi: Match PCI config space accessors against platfrom specific quirks.
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On 19.01.2016 02:49, liudongdong (C) wrote:
> Hi Tomasz, Mark
>
> 在 2016/1/18 20:41, Tomasz Nowicki 写道:
>> 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



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