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

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Date:   Tue, 10 Aug 2021 09:31:30 -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

Hi Jeremy,

On 8/5/21 4:12 PM, Jeremy Linton wrote:
> Now that we have a bcm2711 quirk, we need to be able to
> detect it when the MCFG is missing. Use a namespace
> property as an alternative to the MCFG OEM.
>
> Signed-off-by: Jeremy Linton <jeremy.linton@....com>
> ---
>  drivers/acpi/pci_mcfg.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
>
> 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);
 }