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

On 12/22/2015 10:48 PM, Gabriele Paoloni wrote:

Hi Tomasz

quoted

-----Original Message-----
From: linux-kernel-owner at vger.kernel.org [mailto:linux-kernel-
owner at vger.kernel.org] On Behalf Of Tomasz Nowicki
Sent: 22 December 2015 10:20
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will.deacon at arm.com; catalin.marinas at arm.com; rjw at rjwysocki.net;
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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:

quoted

2) In the quirk mechanism you proposed, I see that the callback

function

quoted

     allows to do some preparation work for the host bridge. For

example in

quoted

     Hisilicon hip05 case we would need to read some values from the

ACPI

quoted

     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"

quoted

     to the  PCI host bridge ACPI device...or maybe we need to declare

a new

quoted

     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?

Let me and Dongdong prepare a patch for Hip05 and then will
back to this discussion to see if we met some problems.

Thanks
Hanjun