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From:   Ben Skeggs <skeggsb@gmail.com>
Date:   Thu, 30 Apr 2020 13:59:39 +1000
Message-ID: <CACAvsv6XmvsnRz7=Brd0dMBfh7FqGA0X_6rz=tTt9M_ess9Lvw@mail.gmail.com>
Subject: Re: [PATCH 1/1] drm/nouveau: Use generic helper to check _PR3 presence
To:     Kai-Heng Feng <kai.heng.feng@canonical.com>
Cc:     Ben Skeggs <bskeggs@redhat.com>, David Airlie <airlied@linux.ie>,
        "open list:DRM DRIVER FOR NVIDIA GEFORCE/QUADRO GPUS" 
        <nouveau@lists.freedesktop.org>,
        open list <linux-kernel@vger.kernel.org>,
        "open list:DRM DRIVER FOR NVIDIA GEFORCE/QUADRO GPUS" 
        <dri-devel@lists.freedesktop.org>
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Sender: linux-kernel-owner@vger.kernel.org
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Thanks!

On Thu, 23 Apr 2020 at 17:37, Kai-Heng Feng <kai.heng.feng@canonical.com> wrote:
>
> Replace nouveau_pr3_present() in favor of a more generic one,
> pci_pr3_present().
>
> Also the presence of upstream bridge _PR3 doesn't need to go hand in
> hand with device's _DSM, so check _PR3 before _DSM.
>
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
> ---
>  drivers/gpu/drm/nouveau/nouveau_acpi.c | 44 ++++++--------------------
>  1 file changed, 10 insertions(+), 34 deletions(-)
>
> diff --git a/drivers/gpu/drm/nouveau/nouveau_acpi.c b/drivers/gpu/drm/nouveau/nouveau_acpi.c
> index fe3a10255c36..b84dff1b0f28 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_acpi.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_acpi.c
> @@ -212,37 +212,6 @@ static const struct vga_switcheroo_handler nouveau_dsm_handler = {
>         .get_client_id = nouveau_dsm_get_client_id,
>  };
>
> -/*
> - * Firmware supporting Windows 8 or later do not use _DSM to put the device into
> - * D3cold, they instead rely on disabling power resources on the parent.
> - */
> -static bool nouveau_pr3_present(struct pci_dev *pdev)
> -{
> -       struct pci_dev *parent_pdev = pci_upstream_bridge(pdev);
> -       struct acpi_device *parent_adev;
> -
> -       if (!parent_pdev)
> -               return false;
> -
> -       if (!parent_pdev->bridge_d3) {
> -               /*
> -                * Parent PCI bridge is currently not power managed.
> -                * Since userspace can change these afterwards to be on
> -                * the safe side we stick with _DSM and prevent usage of
> -                * _PR3 from the bridge.
> -                */
> -               pci_d3cold_disable(pdev);
> -               return false;
> -       }
> -
> -       parent_adev = ACPI_COMPANION(&parent_pdev->dev);
> -       if (!parent_adev)
> -               return false;
> -
> -       return parent_adev->power.flags.power_resources &&
> -               acpi_has_method(parent_adev->handle, "_PR3");
> -}
> -
>  static void nouveau_dsm_pci_probe(struct pci_dev *pdev, acpi_handle *dhandle_out,
>                                   bool *has_mux, bool *has_opt,
>                                   bool *has_opt_flags, bool *has_pr3)
> @@ -250,6 +219,16 @@ static void nouveau_dsm_pci_probe(struct pci_dev *pdev, acpi_handle *dhandle_out
>         acpi_handle dhandle;
>         bool supports_mux;
>         int optimus_funcs;
> +       struct pci_dev *parent_pdev;
> +
> +       *has_pr3 = false;
> +       parent_pdev = pci_upstream_bridge(pdev);
> +       if (parent_pdev) {
> +               if (parent_pdev->bridge_d3)
> +                       *has_pr3 = pci_pr3_present(parent_pdev);
> +               else
> +                       pci_d3cold_disable(pdev);
> +       }
>
>         dhandle = ACPI_HANDLE(&pdev->dev);
>         if (!dhandle)
> @@ -270,7 +249,6 @@ static void nouveau_dsm_pci_probe(struct pci_dev *pdev, acpi_handle *dhandle_out
>         *has_mux = supports_mux;
>         *has_opt = !!optimus_funcs;
>         *has_opt_flags = optimus_funcs & (1 << NOUVEAU_DSM_OPTIMUS_FLAGS);
> -       *has_pr3 = false;
>
>         if (optimus_funcs) {
>                 uint32_t result;
> @@ -280,8 +258,6 @@ static void nouveau_dsm_pci_probe(struct pci_dev *pdev, acpi_handle *dhandle_out
>                          (result & OPTIMUS_ENABLED) ? "enabled" : "disabled",
>                          (result & OPTIMUS_DYNAMIC_PWR_CAP) ? "dynamic power, " : "",
>                          (result & OPTIMUS_HDA_CODEC_MASK) ? "hda bios codec supported" : "");
> -
> -               *has_pr3 = nouveau_pr3_present(pdev);
>         }
>  }
>
> --
> 2.17.1
>
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