linux-kernel - Re: [PATCH v4 1/2] PCI: Refactor pci_bridge_d3

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Message-ID: <CAJZ5v0hhymQ-MSMOc0kCV4as6UhU0oHq0L0LRj4NC=VdAbrwVA@mail.gmail.com>
Date:   Thu, 25 May 2023 15:48:42 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Mario Limonciello <mario.limonciello@....com>
Cc:     Bjorn Helgaas <bhelgaas@...gle.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        S-k Shyam-sundar <Shyam-sundar.S-k@....com>,
        Natikar Basavaraj <Basavaraj.Natikar@....com>,
        Deucher Alexander <Alexander.Deucher@....com>,
        linux-pm@...r.kernel.org, Lukas Wunner <lukas@...ner.de>
Subject: Re: [PATCH v4 1/2] PCI: Refactor pci_bridge_d3_possible()

On Wed, May 24, 2023 at 9:07 PM Mario Limonciello
<mario.limonciello@....com> wrote:
>
> All of the cases handled by pci_bridge_d3_possible() are specific
> to these branches:
> ```
>         case PCI_EXP_TYPE_ROOT_PORT:
>         case PCI_EXP_TYPE_UPSTREAM:
>         case PCI_EXP_TYPE_DOWNSTREAM:
> ```
> Drop a level of indentation by returning false in the default case
> instead.  No intended functional changes.
>
> Signed-off-by: Mario Limonciello <mario.limonciello@....com>

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

> ---
> v3->v4:
>  * New patch
> ---
>  drivers/pci/pci.c | 68 +++++++++++++++++++++++------------------------
>  1 file changed, 34 insertions(+), 34 deletions(-)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 5ede93222bc1..d1fa040bcea7 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -2978,48 +2978,48 @@ bool pci_bridge_d3_possible(struct pci_dev *bridge)
>         case PCI_EXP_TYPE_ROOT_PORT:
>         case PCI_EXP_TYPE_UPSTREAM:
>         case PCI_EXP_TYPE_DOWNSTREAM:
> -               if (pci_bridge_d3_disable)
> -                       return false;
> +               break;
> +       default:
> +               return false;
> +       }
>
> -               /*
> -                * Hotplug ports handled by firmware in System Management Mode
> -                * may not be put into D3 by the OS (Thunderbolt on non-Macs).
> -                */
> -               if (bridge->is_hotplug_bridge && !pciehp_is_native(bridge))
> -                       return false;
> +       if (pci_bridge_d3_disable)
> +               return false;
>
> -               if (pci_bridge_d3_force)
> -                       return true;
> +       /*
> +        * Hotplug ports handled by firmware in System Management Mode
> +        * may not be put into D3 by the OS (Thunderbolt on non-Macs).
> +        */
> +       if (bridge->is_hotplug_bridge && !pciehp_is_native(bridge))
> +               return false;
>
> -               /* Even the oldest 2010 Thunderbolt controller supports D3. */
> -               if (bridge->is_thunderbolt)
> -                       return true;
> +       if (pci_bridge_d3_force)
> +               return true;
>
> -               /* Platform might know better if the bridge supports D3 */
> -               if (platform_pci_bridge_d3(bridge))
> -                       return true;
> +       /* Even the oldest 2010 Thunderbolt controller supports D3. */
> +       if (bridge->is_thunderbolt)
> +               return true;
>
> -               /*
> -                * Hotplug ports handled natively by the OS were not validated
> -                * by vendors for runtime D3 at least until 2018 because there
> -                * was no OS support.
> -                */
> -               if (bridge->is_hotplug_bridge)
> -                       return false;
> +       /* Platform might know better if the bridge supports D3 */
> +       if (platform_pci_bridge_d3(bridge))
> +               return true;
>
> -               if (dmi_check_system(bridge_d3_blacklist))
> -                       return false;
> +       /*
> +        * Hotplug ports handled natively by the OS were not validated
> +        * by vendors for runtime D3 at least until 2018 because there
> +        * was no OS support.
> +        */
> +       if (bridge->is_hotplug_bridge)
> +               return false;
>
> -               /*
> -                * It should be safe to put PCIe ports from 2015 or newer
> -                * to D3.
> -                */
> -               if (dmi_get_bios_year() >= 2015)
> -                       return true;
> -               break;
> -       }
> +       if (dmi_check_system(bridge_d3_blacklist))
> +               return false;
>
> -       return false;
> +       /*
> +        * It should be safe to put PCIe ports from 2015 or newer
> +        * to D3.
> +        */
> +       return dmi_get_bios_year() >= 2015;
>  }
>
>  static int pci_dev_check_d3cold(struct pci_dev *dev, void *data)
> --
> 2.34.1
>