linux-kernel - Re: [PATCH v13 12/12] PCI: ACPI: Limit the Intel specific opt-in to D3 to 2024

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Date:   Fri, 18 Aug 2023 18:09:49 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Mario Limonciello <mario.limonciello@....com>
Cc:     "Rafael J . Wysocki" <rafael@...nel.org>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Bjorn Helgaas <helgaas@...nel.org>, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        linux-acpi@...r.kernel.org,
        Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        Iain Lane <iain@...ngesquash.org.uk>,
        Shyam-sundar S-k <Shyam-sundar.S-k@....com>
Subject: Re: [PATCH v13 12/12] PCI: ACPI: Limit the Intel specific opt-in to
 D3 to 2024

On Fri, Aug 18, 2023 at 7:15 AM Mario Limonciello
<mario.limonciello@....com> wrote:
>
> Intel systems that need to have PCIe ports in D3 for low power idle
> specify this by constraints on the ACPI PNP0D80 device. As this information
> is queried, limit the DMI BIOS year check to stop at 2024. This will
> allow future systems to rely on the constraints check to set up policy
> like non-Intel systems do.
>
> Signed-off-by: Mario Limonciello <mario.limonciello@....com>
> ---
> v12->v13:
>  * New patch
> ---
>  drivers/pci/pci.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 0fc8d35154f97..5b9e11e254f34 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -3049,10 +3049,11 @@ bool pci_bridge_d3_possible(struct pci_dev *bridge)
>                         return true;
>
>                 /*
> -                * It is safe to put Intel PCIe ports from 2015 or newer
> +                * It is safe to put Intel PCIe ports from 2015 to 2024
>                  * to D3.
>                  */
>                 if (bridge->vendor == PCI_VENDOR_ID_INTEL &&
> +                   dmi_get_bios_year() <= 2024 &&
>                     dmi_get_bios_year() >= 2015)

A minor nit: The above would be somewhat easier to follow if it is
written in a reverse order, that is

dmi_get_bios_year() >= 2015 && dmi_get_bios_year() <= 2024

and maybe call dmi_get_bios_year() once to avoid the redundant string parsing?

>                         return true;
>                 break;
> --