linux-kernel - Re: [PATCH v14.a 1/1] PCI: Only put Intel PCIe ports >= 2015 into D3

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Message-ID: <CAJZ5v0gwFKHLtd9rqNAe5ozgp_EWi3A158VukcX0oA4LBPBfOQ@mail.gmail.com>
Date:   Mon, 21 Aug 2023 20:17:16 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Mario Limonciello <mario.limonciello@....com>
Cc:     Mika Westerberg <mika.westerberg@...ux.intel.com>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Bjorn Helgaas <helgaas@...nel.org>, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
        Iain Lane <iain@...ngesquash.org.uk>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        stable@...r.kernel.org
Subject: Re: [PATCH v14.a 1/1] PCI: Only put Intel PCIe ports >= 2015 into D3

On Fri, Aug 18, 2023 at 9:40 PM Mario Limonciello
<mario.limonciello@....com> wrote:
>
> commit 9d26d3a8f1b0 ("PCI: Put PCIe ports into D3 during suspend")
> changed pci_bridge_d3_possible() so that any vendor's PCIe ports
> from modern machines (>=2015) are allowed to be put into D3.
>
> Iain reports that USB devices can't be used to wake a Lenovo Z13
> from suspend. This is because the PCIe root port has been put
> into D3 and AMD's platform can't handle USB devices waking in this
> case.
>
> This behavior is only reported on Linux. Comparing the behavior
> on Windows and Linux, Windows doesn't put the root ports into D3.
>
> To fix the issue without regressing existing Intel systems,
> limit the >=2015 check to only apply to Intel PCIe ports.
>
> Cc: stable@...r.kernel.org
> Fixes: 9d26d3a8f1b0 ("PCI: Put PCIe ports into D3 during suspend")
> Reported-by: Iain Lane <iain@...ngesquash.org.uk>
> Closes: https://forums.lenovo.com/t5/Ubuntu/Z13-can-t-resume-from-suspend-with-external-USB-keyboard/m-p/5217121
> Reviewed-by:Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
> Signed-off-by: Mario Limonciello <mario.limonciello@....com>

Acked-by: Rafael J. Wysocki <rafael@...nel.org>

> ---
> In v14 this series has been split into 3 parts.
>  part A: Immediate fix for AMD issue.
>  part B: LPS0 export improvements
>  part C: Long term solution for all vendors
> v13->v14:
>  * Reword the comment
>  * add tag
> v12->v13:
>  * New patch
> ---
>  drivers/pci/pci.c | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 60230da957e0c..bfdad2eb36d13 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -3037,10 +3037,15 @@ bool pci_bridge_d3_possible(struct pci_dev *bridge)
>                         return false;
>
>                 /*
> -                * It should be safe to put PCIe ports from 2015 or newer
> -                * to D3.
> +                * Allow Intel PCIe ports from 2015 onward to go into D3 to
> +                * achieve additional energy conservation on some platforms.
> +                *
> +                * This is only set for Intel PCIe ports as it causes problems
> +                * on both AMD Rembrandt and Phoenix platforms where USB keyboards
> +                * can not be used to wake the system from suspend.
>                  */
> -               if (dmi_get_bios_year() >= 2015)
> +               if (bridge->vendor == PCI_VENDOR_ID_INTEL &&
> +                   dmi_get_bios_year() >= 2015)
>                         return true;
>                 break;
>         }
> --
> 2.34.1
>