linux-kernel - Re: [PATCH] PCI/MSI: Don't set up INTx if MSI or MSI-X is enabled

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Message-ID: <CAHp75Vfp_uwSLe_ENnr=azJGrMoR6DuvGSCi5DSeq6=B-ghAGg@mail.gmail.com>
Date:   Wed, 14 Mar 2018 18:31:38 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Bjorn Helgaas <helgaas@...nel.org>
Cc:     linux-pci@...r.kernel.org, Mikael Starvik <starvik@...s.com>,
        Jesper Nilsson <jesper.nilsson@...s.com>,
        Tony Luck <tony.luck@...el.com>,
        Fenghua Yu <fenghua.yu@...el.com>,
        David Howells <dhowells@...hat.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Cris <linux-cris-kernel@...s.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-ia64@...r.kernel.org, linux-am33-list@...hat.com
Subject: Re: [PATCH] PCI/MSI: Don't set up INTx if MSI or MSI-X is enabled

On Tue, Mar 13, 2018 at 11:45 PM, Bjorn Helgaas <helgaas@...nel.org> wrote:
> From: Bjorn Helgaas <bhelgaas@...gle.com>
>

Agree with Christoph's comment.

> If a device already has MSI or MSI-X enabled, there's no need to set up its
> legacy INTx interrupt.

Just point to the actual behaviour of this. In some cases code in
question has to distinguish between MSI and MSI-x.
So, this or similar changes has to be done with keeping above in mind.

(Existing example is Thunderbolt driver)

>
> bba6f6fc68e7 ("[PATCH] MSI-X: fix resume crash") changed the cris, frv,
> x86, and ia64 arches to skip INTx setup when MSI is enabled.
>
> 16cf0ebc35dd ("x86/PCI: Do not use interrupt links for devices using
> MSI-X") extended that by changing x86 to also skip INTx setup when MSI-X is
> enabled.
>
> Change the remaining arches (cris, frv, and ia64) to skip INTx setup when
> either MSI or MSI-X is enabled.
>
> Also update mn10300 (which didn't exist at the time of bba6f6fc68e7) to
> follow the same pattern.

Perhaps no need to change the architectures that are about to be
removed completely from the kernel.

FWIW,
Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>

> Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
> ---
>  arch/cris/arch-v32/drivers/pci/bios.c |    2 +-
>  arch/frv/mb93090-mb00/pci-vdk.c       |    2 +-
>  arch/ia64/pci/pci.c                   |    4 ++--
>  arch/mn10300/unit-asb2305/pci.c       |    8 +++++---
>  4 files changed, 9 insertions(+), 7 deletions(-)
>
> diff --git a/arch/cris/arch-v32/drivers/pci/bios.c b/arch/cris/arch-v32/drivers/pci/bios.c
> index 6b9e6cfaa29e..c2bed0cc060b 100644
> --- a/arch/cris/arch-v32/drivers/pci/bios.c
> +++ b/arch/cris/arch-v32/drivers/pci/bios.c
> @@ -68,7 +68,7 @@ int pcibios_enable_device(struct pci_dev *dev, int mask)
>         if ((err = pcibios_enable_resources(dev, mask)) < 0)
>                 return err;
>
> -       if (!dev->msi_enabled)
> +       if (!pci_dev_msi_enabled(dev))
>                 pcibios_enable_irq(dev);
>         return 0;
>  }
> diff --git a/arch/frv/mb93090-mb00/pci-vdk.c b/arch/frv/mb93090-mb00/pci-vdk.c
> index f211839e2cae..4a55d1b82d21 100644
> --- a/arch/frv/mb93090-mb00/pci-vdk.c
> +++ b/arch/frv/mb93090-mb00/pci-vdk.c
> @@ -413,7 +413,7 @@ int pcibios_enable_device(struct pci_dev *dev, int mask)
>
>         if ((err = pci_enable_resources(dev, mask)) < 0)
>                 return err;
> -       if (!dev->msi_enabled)
> +       if (!pci_dev_msi_enabled(dev))
>                 pcibios_enable_irq(dev);
>         return 0;
>  }
> diff --git a/arch/ia64/pci/pci.c b/arch/ia64/pci/pci.c
> index f5ec736100ee..7ccc64d5fe3e 100644
> --- a/arch/ia64/pci/pci.c
> +++ b/arch/ia64/pci/pci.c
> @@ -398,7 +398,7 @@ pcibios_enable_device (struct pci_dev *dev, int mask)
>         if (ret < 0)
>                 return ret;
>
> -       if (!dev->msi_enabled)
> +       if (!pci_dev_msi_enabled(dev))
>                 return acpi_pci_irq_enable(dev);
>         return 0;
>  }
> @@ -407,7 +407,7 @@ void
>  pcibios_disable_device (struct pci_dev *dev)
>  {
>         BUG_ON(atomic_read(&dev->enable_cnt));
> -       if (!dev->msi_enabled)
> +       if (!pci_dev_msi_enabled(dev))
>                 acpi_pci_irq_disable(dev);
>  }
>
> diff --git a/arch/mn10300/unit-asb2305/pci.c b/arch/mn10300/unit-asb2305/pci.c
> index 3dfe2d31c67b..4d36ea517679 100644
> --- a/arch/mn10300/unit-asb2305/pci.c
> +++ b/arch/mn10300/unit-asb2305/pci.c
> @@ -399,10 +399,12 @@ int pcibios_enable_device(struct pci_dev *dev, int mask)
>  {
>         int err;
>
> -       err = pci_enable_resources(dev, mask);
> -       if (err == 0)
> +       if ((err = pci_enable_resources(dev, mask)) < 0)
> +               return err;
> +
> +       if (!pci_dev_msi_enabled(dev))
>                 pcibios_enable_irq(dev);
> -       return err;
> +       return 0;
>  }
>
>  /*
>



-- 
With Best Regards,
Andy Shevchenko