linux-kernel - Re: [PATCH v3 1/4] of/pci: Add of_pci_check_probe

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Date:	Thu, 3 Sep 2015 09:01:43 -0500
From:	Rob Herring <robherring2@...il.com>
To:	Marc Zyngier <marc.zyngier@....com>
Cc:	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mackerras <paulus@...ba.org>,
	Michael Ellerman <mpe@...erman.id.au>,
	Will Deacon <will.deacon@....com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Suravee Suthikulpanit <Suravee.Suthikulpanit@....com>,
	Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
	Grant Likely <grant.likely@...aro.org>,
	Rob Herring <robh+dt@...nel.org>,
	Alexander Graf <agraf@...e.de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Subject: Re: [PATCH v3 1/4] of/pci: Add of_pci_check_probe_only to parse "linux,pci-probe-only"

On Thu, Sep 3, 2015 at 7:16 AM, Marc Zyngier <marc.zyngier@....com> wrote:
> Both pci-host-generic and Pseries parse the "linux,pci-probe-only"
> property to engage the PCI_PROBE_ONLY mode, and both have a subtle
> bug that can be triggered if the property has no parameter.
>
> Provide a generic, safe implementation that can be used by both.

Sorry, but a couple of other minor things I noticed.

>
> Signed-off-by: Marc Zyngier <marc.zyngier@....com>
> ---
>  drivers/of/of_pci.c    | 31 +++++++++++++++++++++++++++++++
>  include/linux/of_pci.h |  3 +++
>  2 files changed, 34 insertions(+)
>
> diff --git a/drivers/of/of_pci.c b/drivers/of/of_pci.c
> index 5751dc5..7876343 100644
> --- a/drivers/of/of_pci.c
> +++ b/drivers/of/of_pci.c
> @@ -118,6 +118,37 @@ int of_get_pci_domain_nr(struct device_node *node)
>  EXPORT_SYMBOL_GPL(of_get_pci_domain_nr);
>
>  /**
> + * of_pci_check_probe_only - Setup probe only mode if linux,pci-probe-only
> + *                           is present and valid
> + *
> + * @node: device tree node that may contain the property (usually "chosen")
> + *
> + */
> +void of_pci_check_probe_only(struct device_node *node)

This property is only valid in /chosen, so there's no point passing
of_chosen in and you can constrain it to only look in /chosen.

> +{
> +       u32 val;
> +       int ret;
> +
> +       if (!node)
> +               return;

I believe of_property_read_u32 will check this.

> +
> +       ret = of_property_read_u32(node, "linux,pci-probe-only", &val);
> +       if (ret) {
> +               if (ret == -ENODATA || ret == -EOVERFLOW)
> +                       pr_warn("linux,pci-probe-only without valid value, ignoring\n");
> +               return;
> +       }
> +
> +       if (val)
> +               pci_add_flags(PCI_PROBE_ONLY);
> +       else
> +               pci_clear_flags(PCI_PROBE_ONLY);
> +
> +       pr_info("PCI: PROBE_ONLY %sabled\n", val ? "en" : "dis");
> +}
> +EXPORT_SYMBOL_GPL(of_pci_check_probe_only);
> +
> +/**
>   * of_pci_dma_configure - Setup DMA configuration
>   * @dev: ptr to pci_dev struct of the PCI device
>   *
> diff --git a/include/linux/of_pci.h b/include/linux/of_pci.h
> index 29fd3fe..4c0a617 100644
> --- a/include/linux/of_pci.h
> +++ b/include/linux/of_pci.h
> @@ -17,6 +17,7 @@ int of_irq_parse_and_map_pci(const struct pci_dev *dev, u8 slot, u8 pin);
>  int of_pci_parse_bus_range(struct device_node *node, struct resource *res);
>  int of_get_pci_domain_nr(struct device_node *node);
>  void of_pci_dma_configure(struct pci_dev *pci_dev);
> +void of_pci_check_probe_only(struct device_node *node);
>  #else
>  static inline int of_irq_parse_pci(const struct pci_dev *pdev, struct of_phandle_args *out_irq)
>  {
> @@ -53,6 +54,8 @@ of_get_pci_domain_nr(struct device_node *node)
>  }
>
>  static inline void of_pci_dma_configure(struct pci_dev *pci_dev) { }
> +
> +static inline void of_pci_check_probe_only(struct device_node *node) { }
>  #endif
>
>  #if defined(CONFIG_OF_ADDRESS)
> --
> 2.1.4
>
--
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