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From: "Rafael J. Wysocki" <rafael@kernel.org>
Date: Wed, 14 Mar 2018 12:48:49 +0100
Message-ID: <CAJZ5v0gOrQhXzLHDnABEYHxGbHVY89Nij9uQzqx-oyYmFwzuSg@mail.gmail.com>
Subject: Re: [PATCH 1/2] PCI/DPC: Disable interrupt generation during suspend
To: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>,
        "Rafael J . Wysocki" <rjw@rjwysocki.net>,
        Len Brown <lenb@kernel.org>,
        Keith Busch <keith.busch@intel.com>,
        Linux PCI <linux-pci@vger.kernel.org>,
        ACPI Devel Maling List <linux-acpi@vger.kernel.org>
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On Wed, Mar 14, 2018 at 12:41 PM, Mika Westerberg
<mika.westerberg@linux.intel.com> wrote:
> When system is resumed if the interrupt generation is enabled it may
> trigger immediately when interrupts are enabled depending on what is in
> the status register. This may generate spurious DPC conditions and
> unnecessary removal of devices.
>
> Make this work better with system suspend and disable interrupt
> generation when the system is suspended.
>
> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
> ---
>  drivers/pci/pcie/pcie-dpc.c | 29 +++++++++++++++++++++++++----
>  1 file changed, 25 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/pci/pcie/pcie-dpc.c b/drivers/pci/pcie/pcie-dpc.c
> index 38e40c6c576f..14b96983dbbd 100644
> --- a/drivers/pci/pcie/pcie-dpc.c
> +++ b/drivers/pci/pcie/pcie-dpc.c
> @@ -280,23 +280,44 @@ static int dpc_probe(struct pcie_device *dev)
>         return status;
>  }
>
> -static void dpc_remove(struct pcie_device *dev)
> +static void dpc_interrupt_enable(struct dpc_dev *dpc, bool enable)
>  {
> -       struct dpc_dev *dpc = get_service_data(dev);
> -       struct pci_dev *pdev = dev->port;
> +       struct pci_dev *pdev = dpc->dev->port;
>         u16 ctl;
>
>         pci_read_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_CTL, &ctl);
> -       ctl &= ~(PCI_EXP_DPC_CTL_EN_NONFATAL | PCI_EXP_DPC_CTL_INT_EN);
> +       if (enable)
> +               ctl |= PCI_EXP_DPC_CTL_EN_NONFATAL | PCI_EXP_DPC_CTL_INT_EN;
> +       else
> +               ctl &= ~(PCI_EXP_DPC_CTL_EN_NONFATAL | PCI_EXP_DPC_CTL_INT_EN);
>         pci_write_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_CTL, ctl);
>  }
>
> +static void dpc_remove(struct pcie_device *dev)
> +{
> +       dpc_interrupt_enable(get_service_data(dev), false);
> +}
> +
> +static int dpc_suspend(struct pcie_device *dev)
> +{
> +       dpc_interrupt_enable(get_service_data(dev), false);
> +       return 0;
> +}
> +
> +static int dpc_resume(struct pcie_device *dev)
> +{
> +       dpc_interrupt_enable(get_service_data(dev), true);
> +       return 0;
> +}

Have you considered putting these things into the ->suspend_late and
->resume_early callbacks, respectively?

That might be slightly better as runtime resume is still enabled when
the ->suspend and ->resume callbacks run.

> +
>  static struct pcie_port_service_driver dpcdriver = {
>         .name           = "dpc",
>         .port_type      = PCIE_ANY_PORT,
>         .service        = PCIE_PORT_SERVICE_DPC,
>         .probe          = dpc_probe,
>         .remove         = dpc_remove,
> +       .suspend        = dpc_suspend,
> +       .resume         = dpc_resume,
>  };
>
>  static int __init dpc_service_init(void)
> --