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

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Date:	Tue, 19 Jan 2016 09:49:40 +0800
From:	"liudongdong (C)" <liudongdong3@...wei.com>
To:	Tomasz Nowicki <tn@...ihalf.com>, Mark Salter <msalter@...hat.com>,
	<bhelgaas@...gle.com>, <arnd@...db.de>, <will.deacon@....com>,
	<catalin.marinas@....com>, <rjw@...ysocki.net>,
	<hanjun.guo@...aro.org>, <Lorenzo.Pieralisi@....com>,
	<okaya@...eaurora.org>, <jiang.liu@...ux.intel.com>,
	<Stefano.Stabellini@...citrix.com>
CC:	<robert.richter@...iumnetworks.com>, <mw@...ihalf.com>,
	<Liviu.Dudau@....com>, <ddaney@...iumnetworks.com>,
	<tglx@...utronix.de>, <wangyijing@...wei.com>,
	<Suravee.Suthikulpanit@....com>, <linux-pci@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-acpi@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linaro-acpi@...ts.linaro.org>, <jchandra@...adcom.com>,
	<jcm@...hat.com>, Zhou Wang <wangzhou1@...ilicon.com>,
	Gabriele Paoloni <gabriele.paoloni@...wei.com>
Subject: Re: [PATCH V3 20/21] pci, acpi: Match PCI config space accessors
 against platfrom specific quirks.

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.

Device (PCI1)
{
         Name (_HID, "HISI0080") // PCI Express Root Bridge
         Name (_CID, "PNP0A03") // Compatible PCI Root Bridge
	...
}

static const struct acpi_device_id hisi_pcie_ids[] = {
     {"HISI0080", 0},
     {"", 0},
};

static int hisi_pcie_match(struct pci_mcfg_fixup *fixup, struct acpi_pci_root *root)
{
     int ret;
     struct acpi_device *device;

     device = root->device;
     ret = acpi_match_device_ids(device, hisi_pcie_ids);
     if (ret)
         return 0;
     ......
     return 1;
}

static struct pci_ops hisi_ecam_pci_ops = {
     .map_bus = pci_mcfg_dev_base,
     .read = hisi_pci_read,
     .write = hisi_pci_write,
};

DECLARE_ACPI_MCFG_FIXUP(NULL, hisi_pcie_match, &hisi_ecam_pci_ops,
     PCI_MCFG_DOMAIN_ANY, PCI_MCFG_BUS_ANY);

Thanks
Dongdong
> Makes a lot of sense to me, I will modify as you suggested.
>
> Tomasz
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