linux-kernel - Re: [PATCH v2 3/4] PCI/ACPI: Add Broadcom bcm2711 MCFG quirk

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Message-ID: <9796674a-5870-135c-2fdc-fb0d5347d7c7@gmail.com>
Date:   Sun, 22 Aug 2021 10:53:33 +0200
From:   Florian Fainelli <f.fainelli@...il.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,
        sdonthineni@...dia.com, stefan.wahren@...e.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 v2 3/4] PCI/ACPI: Add Broadcom bcm2711 MCFG quirk



On 8/19/2021 11:56 PM, Jeremy Linton wrote:
> Now that there is a bcm2711 quirk, it needs to be enabled when the
> MCFG is missing. Use an ACPI namespace _DSD property
> "linux-ecam-quirk-id" as an alternative to the MCFG OEM.
> 
> Signed-off-by: Jeremy Linton <jeremy.linton@....com>
> ---
>   drivers/acpi/pci_mcfg.c | 13 +++++++++++++
>   1 file changed, 13 insertions(+)
> 
> diff --git a/drivers/acpi/pci_mcfg.c b/drivers/acpi/pci_mcfg.c
> index 53cab975f612..4b991ee5c66c 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 +201,18 @@ 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 may be a machine with a PCI/SMC conduit, which means it doesn't
> +	 * have an MCFG. Use an ACPI namespace definition instead.
> +	 */
> +	if (!fwnode_property_read_string(acpi_fwnode_handle(root->device),
> +					 "linux-ecam-quirk-id", &soc)) {
> +		memcpy(mcfg_oem_id, soc, ACPI_OEM_ID_SIZE);

Being super paranoid here, can we use one of the "safe" string copy 
routines here just in case?

> +	}
> +
>   	for (i = 0, f = mcfg_quirks; i < ARRAY_SIZE(mcfg_quirks); i++, f++) {
>   		if (pci_mcfg_quirk_matches(f, segment, bus_range)) {
>   			if (f->cfgres.start)
> 

-- 
Florian