RE: [PATCH V2 22/23] pci, acpi: Match PCI config space accessors against platfrom specific quirks.

[Gabriele Paoloni]

Hi Tomasz

> -----Original Message-----
> From: linux-kernel-owner@xxxxxxxxxxxxxxx [mailto:linux-kernel-
> owner@xxxxxxxxxxxxxxx] On Behalf Of Tomasz Nowicki
> Sent: 22 December 2015 10:20
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> Subject: Re: [PATCH V2 22/23] pci, acpi: Match PCI config space
> accessors against platfrom specific quirks.
> 
> On 21.12.2015 12:47, Gabriele Paoloni wrote:
> > 2) In the quirk mechanism you proposed, I see that the callback
> function
> >     allows to do some preparation work for the host bridge. For
> example in
> >     Hisilicon hip05 case we would need to read some values from the
> ACPI
> >     table (see acpi_pci_root_hisi_add() function in
> >     https://lkml.org/lkml/2015/12/3/426).
> >     I am quite new to ACPI and I wonder if it is OK to add such
> "Packages"
> >     to the  PCI host bridge ACPI device...or maybe we need to declare
> a new
> >     one...?
> 
> I may miss sth so please correct me in that case.
> 
> https://lkml.org/lkml/2015/12/3/426 shows that you need special
> handling for root->secondary.start bus number only, right? So how about
> creating special MCFG region <rc-base:rc-base+rc-size> only for
> <segment,bus>.
> Like that:
> 
> [0008]                       Base Address : <rc-base>
> [0002]               Segment Group Number : <segment>
> [0001]                   Start Bus Number : <root->secondary.start>
> [0001]                     End Bus Number : <root->secondary.start>
> [0004]                           Reserved : 00000000
> 
> 
> static const struct dmi_system_id hisi_quirk[] = {
> 	{
> 		.ident = "HiSi...",
> 		.matches = {
> 			DMI_MATCH(<whatever you need to match your platform>),
> 		},
> 	},
> 	{ }
> };
> 
> static struct pci_ops hisi_ecam_pci_ops = {
> 	.map_bus = pci_mcfg_dev_base,
> 	.read = hisi_pcie_cfg_read,
> 	.write = hisi_pcie_cfg_write,
> };
> 
> DECLARE_ACPI_MCFG_FIXUP(hisi_quirk, &hisi_ecam_pci_ops,
> 			<segment>, <bus>);
> 
> With above code you can use your custom PCI config accessor only for
> that region.
> 
> Let me know if that is not enough for you.

In principle I think it can work...

Liudongdong, Guo Hanjun what is your opinion about?

Thanks

Gab

> 
> Tomasz
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