linux-kernel - Re: [PATCH] PCI: Restrict device disabled status check to DT

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Date:   Thu, 20 Apr 2023 08:14:38 +0100
From:   Donald Hunter <donald.hunter@...il.com>
To:     Rob Herring <robh@...nel.org>
Cc:     Bjorn Helgaas <bhelgaas@...gle.com>,
        Binbin Zhou <zhoubinbin@...ngson.cn>,
        Liu Peibao <liupeibao@...ngson.cn>,
        Huacai Chen <chenhuacai@...ngson.cn>,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] PCI: Restrict device disabled status check to DT

On Wed, 19 Apr 2023 at 20:45, Rob Herring <robh@...nel.org> wrote:
>
> Commit 6fffbc7ae137 ("PCI: Honor firmware's device disabled status")
> checked the firmware device status for both DT and ACPI devices. That
> caused a regression in some ACPI systems. The exact reason isn't clear.
> It's possibly a firmware bug. For now, at least, refactor the check to
> be for DT based systems only.
>
> Note that the original implementation leaked a refcount which is now
> correctly handled.
>
> Fixes: 6fffbc7ae137 ("PCI: Honor firmware's device disabled status")
> Link: https://lore.kernel.org/all/m2fs9lgndw.fsf@gmail.com/
> Reported-by: Donald Hunter <donald.hunter@...il.com>
> Cc: Binbin Zhou <zhoubinbin@...ngson.cn>
> Cc: Liu Peibao <liupeibao@...ngson.cn>
> Cc: Huacai Chen <chenhuacai@...ngson.cn>
> Signed-off-by: Rob Herring <robh@...nel.org>

Tested-by: Donald Hunter <donald.hunter@...il.com>

Thanks!

> ---
>  drivers/pci/of.c    | 30 ++++++++++++++++++++++++------
>  drivers/pci/pci.h   |  4 ++--
>  drivers/pci/probe.c |  8 ++++----
>  3 files changed, 30 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/pci/of.c b/drivers/pci/of.c
> index 196834ed44fe..4c2ef2e28fb5 100644
> --- a/drivers/pci/of.c
> +++ b/drivers/pci/of.c
> @@ -16,14 +16,32 @@
>  #include "pci.h"
>
>  #ifdef CONFIG_PCI
> -void pci_set_of_node(struct pci_dev *dev)
> +/**
> + * pci_set_of_node - Find and set device's DT device_node
> + * @dev: the PCI device structure to fill
> + *
> + * Returns 0 on success with of_node set or when no device is described in the
> + * DT. Returns -ENODEV if the device is present, but disabled in the DT.
> + */
> +int pci_set_of_node(struct pci_dev *dev)
>  {
> +       struct device_node *node;
> +
>         if (!dev->bus->dev.of_node)
> -               return;
> -       dev->dev.of_node = of_pci_find_child_device(dev->bus->dev.of_node,
> -                                                   dev->devfn);
> -       if (dev->dev.of_node)
> -               dev->dev.fwnode = &dev->dev.of_node->fwnode;
> +               return 0;
> +
> +       node = of_pci_find_child_device(dev->bus->dev.of_node, dev->devfn);
> +       if (!node)
> +               return 0;
> +
> +       if (!of_device_is_available(node)) {
> +               of_node_put(node);
> +               return -ENODEV;
> +       }
> +
> +       dev->dev.of_node = node;
> +       dev->dev.fwnode = &node->fwnode;
> +       return 0;
>  }
>
>  void pci_release_of_node(struct pci_dev *dev)
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index d2c08670a20e..2b48a0aa8008 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -624,7 +624,7 @@ int of_pci_get_max_link_speed(struct device_node *node);
>  u32 of_pci_get_slot_power_limit(struct device_node *node,
>                                 u8 *slot_power_limit_value,
>                                 u8 *slot_power_limit_scale);
> -void pci_set_of_node(struct pci_dev *dev);
> +int pci_set_of_node(struct pci_dev *dev);
>  void pci_release_of_node(struct pci_dev *dev);
>  void pci_set_bus_of_node(struct pci_bus *bus);
>  void pci_release_bus_of_node(struct pci_bus *bus);
> @@ -662,7 +662,7 @@ of_pci_get_slot_power_limit(struct device_node *node,
>         return 0;
>  }
>
> -static inline void pci_set_of_node(struct pci_dev *dev) { }
> +static inline int pci_set_of_node(struct pci_dev *dev) { return 0; }
>  static inline void pci_release_of_node(struct pci_dev *dev) { }
>  static inline void pci_set_bus_of_node(struct pci_bus *bus) { }
>  static inline void pci_release_bus_of_node(struct pci_bus *bus) { }
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index a3f68b6ba6ac..f96fa83f2627 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -1826,7 +1826,7 @@ int pci_setup_device(struct pci_dev *dev)
>         u32 class;
>         u16 cmd;
>         u8 hdr_type;
> -       int pos = 0;
> +       int err, pos = 0;
>         struct pci_bus_region region;
>         struct resource *res;
>
> @@ -1840,10 +1840,10 @@ int pci_setup_device(struct pci_dev *dev)
>         dev->error_state = pci_channel_io_normal;
>         set_pcie_port_type(dev);
>
> -       pci_set_of_node(dev);
> +       err = pci_set_of_node(dev);
> +       if (err)
> +               return err;
>         pci_set_acpi_fwnode(dev);
> -       if (dev->dev.fwnode && !fwnode_device_is_available(dev->dev.fwnode))
> -               return -ENODEV;
>
>         pci_dev_assign_slot(dev);
>
> --
> 2.39.2
>