linux-kernel - Re: [PATCH 3/3] PCI/ACPI: Add new quirk detection, enable bcm2711

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Date:   Tue, 10 Aug 2021 10:09:35 -0500
From:   Shanker R Donthineni <sdonthineni@...dia.com>
To:     Jeremy Linton <jeremy.linton@....com>, <linux-pci@...r.kernel.org>
CC:     <lorenzo.pieralisi@....com>, <nsaenz@...nel.org>,
        <bhelgaas@...gle.com>, <rjw@...ysocki.net>, <lenb@...nel.org>,
        <robh@...nel.org>, <kw@...ux.com>, <f.fainelli@...il.com>,
        <bcm-kernel-feedback-list@...adcom.com>,
        <linux-acpi@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-rpi-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/3] PCI/ACPI: Add new quirk detection, enable bcm2711



On 8/10/21 9:47 AM, Jeremy Linton wrote:
>>> diff --git a/drivers/acpi/pci_mcfg.c b/drivers/acpi/pci_mcfg.c
>>> index 53cab975f612..7d77fc72c2a4 100644
>>> --- a/drivers/acpi/pci_mcfg.c
>>> +++ b/drivers/acpi/pci_mcfg.c
>>> @@ -169,6 +169,9 @@ static struct mcfg_fixup mcfg_quirks[] = {
>>>          ALTRA_ECAM_QUIRK(1, 13),
>>>          ALTRA_ECAM_QUIRK(1, 14),
>>>          ALTRA_ECAM_QUIRK(1, 15),
>>> +
>>> +       { "bcm2711", "", 0, 0, MCFG_BUS_ANY, &bcm2711_pcie_ops,
>>> +         DEFINE_RES_MEM(0xFD500000, 0xA000) },
>>>   };
>>>
>>>   static char mcfg_oem_id[ACPI_OEM_ID_SIZE];
>>> @@ -198,8 +201,19 @@ static void pci_mcfg_apply_quirks(struct acpi_pci_root *root,
>>>          u16 segment = root->segment;
>>>          struct resource *bus_range = &root->secondary;
>>>          struct mcfg_fixup *f;
>>> +       const char *soc;
>>>          int i;
>>>
>>> +       /*
>>> +        * This could be a machine with a PCI/SMC conduit,
>>> +        * which means it doens't have MCFG. Get the machineid from
>>> +        * the namespace definition instead.
>>> +        */
>>> +       if (!fwnode_property_read_string(acpi_fwnode_handle(root->device),
>>> +                                        "linux,pcie-quirk", &soc)) {
>>> +               memcpy(mcfg_oem_id, soc, ACPI_OEM_ID_SIZE);
>>> +       }
>>> +
>>
>> Is there any specific reason for not using the firmware agnostic API to get properties?
>>
>>
>>   if (!device_property_read_string(root->device, "linux,pcie-quirk", &soc)) {
>>       memcpy(mcfg_oem_id, soc, ACPI_OEM_ID_SIZE);
>>   }
>>
>>
>
> IIRC it was because the "device" here isn't a struct device, rather a
> struct acpi_device. I think this is the normal way in this situation
> since we are directly picking up the fwnode rather than finding a
> generic node and then backtracking to get the fwnode. 

Yes, you are right.