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Date: Fri, 26 Sep 2014 22:20:53 +0100
From: liviu@...au.co.uk
To: Rob Herring <robherring2@...il.com>
Cc: Liviu Dudau <Liviu.Dudau@....com>,
Bjorn Helgaas <bhelgaas@...gle.com>,
Arnd Bergmann <arnd@...db.de>,
Rob Herring <robh+dt@...nel.org>,
Jason Gunthorpe <jgunthorpe@...idianresearch.com>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <Will.Deacon@....com>,
Russell King <linux@....linux.org.uk>,
linux-pci <linux-pci@...r.kernel.org>,
Linus Walleij <linus.walleij@...aro.org>,
Tanmay Inamdar <tinamdar@....com>,
Grant Likely <grant.likely@...retlab.ca>,
Sinan Kaya <okaya@...eaurora.org>,
Jingoo Han <jg1.han@...sung.com>,
Kukjin Kim <kgene.kim@...sung.com>,
Suravee Suthikulanit <suravee.suthikulpanit@....com>,
linux-arch <linux-arch@...r.kernel.org>,
LKML <linux-kernel@...r.kernel.org>,
Device Tree ML <devicetree@...r.kernel.org>,
LAKML <linux-arm-kernel@...ts.infradead.org>,
Grant Likely <grant.likely@...aro.org>
Subject: Re: [PATCH v12 08/12] PCI: OF: Introduce helper function for
retrieving PCI domain numbers
On Fri, Sep 26, 2014 at 01:20:39PM -0500, Rob Herring wrote:
> On Tue, Sep 23, 2014 at 2:01 PM, Liviu Dudau <Liviu.Dudau@....com> wrote:
> > Add pci_get_new_domain_nr() to allocate a new domain number
> > and of_get_pci_domain_nr() to retrieve the PCI domain number
> > of a given device from DT. Host bridge drivers or architecture
> > specific code can choose to implement their PCI domain number
> > policy using these two functions.
> >
> > Using of_get_pci_domain_nr() guarantees a stable PCI domain
> > number on every boot provided that all host bridge controllers
> > are assigned a number in the device tree using "linux,pci-domain"
> > property. Mix use of pci_get_new_domain_nr() and of_get_pci_domain_nr()
> > is not recommended as it can lead to potentially conflicting
> > domain numbers being assigned to root busses behind different
> > host bridges.
> >
> > Cc: Bjorn Helgaas <bhelgaas@...gle.com>
> > Cc: Arnd Bergmann <arnd@...db.de>
> > Cc: Grant Likely <grant.likely@...aro.org>
> > Cc: Rob Herring <robh+dt@...nel.org>
> > Cc: Catalin Marinas <catalin.marinas@....com>
> > Signed-off-by: Liviu Dudau <Liviu.Dudau@....com>
>
> Looks pretty good, but a couple of comments that can be addressed as
> follow-up patches.
>
> > ---
> > drivers/of/of_pci.c | 25 +++++++++++++++++++++++++
> > drivers/pci/pci.c | 9 +++++++++
> > include/linux/of_pci.h | 7 +++++++
> > include/linux/pci.h | 3 +++
> > 4 files changed, 44 insertions(+)
> >
> > diff --git a/drivers/of/of_pci.c b/drivers/of/of_pci.c
> > index 8481996..82d172f 100644
> > --- a/drivers/of/of_pci.c
> > +++ b/drivers/of/of_pci.c
> > @@ -89,6 +89,31 @@ int of_pci_parse_bus_range(struct device_node *node, struct resource *res)
> > }
> > EXPORT_SYMBOL_GPL(of_pci_parse_bus_range);
> >
> > +/**
> > + * This function will try to obtain the host bridge domain number by
> > + * finding a property called "linux,pci-domain" of the given device node.
> > + *
> > + * @node: device tree node with the domain information
> > + *
> > + * Returns the associated domain number from DT in the range [0-0xffff], or
> > + * a negative value if the required property is not found.
> > + */
> > +int of_get_pci_domain_nr(struct device_node *node)
> > +{
> > + const __be32 *value;
> > + int len;
> > + u16 domain;
> > +
> > + value = of_get_property(node, "linux,pci-domain", &len);
>
> This needs to be documented.
I would say needs agreed on *and* documented.
>
> > + if (!value || len < sizeof(*value))
> > + return -EINVAL;
> > +
> > + domain = (u16)be32_to_cpup(value);
>
> of_property_read_u32 would not work here?
It should, I guess, but I want to limit the domain number range to 16 bits.
Best regards,
Liviu
>
> > +
> > + return domain;
> > +}
> > +EXPORT_SYMBOL_GPL(of_get_pci_domain_nr);
> > +
> > #ifdef CONFIG_PCI_MSI
> >
> > static LIST_HEAD(of_pci_msi_chip_list);
> > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> > index 2c9ac70..d36f35f 100644
> > --- a/drivers/pci/pci.c
> > +++ b/drivers/pci/pci.c
> > @@ -4406,6 +4406,15 @@ static void pci_no_domains(void)
> > #endif
> > }
> >
> > +#ifdef CONFIG_PCI_DOMAINS
> > +static atomic_t __domain_nr = ATOMIC_INIT(-1);
> > +
> > +int pci_get_new_domain_nr(void)
> > +{
> > + return atomic_inc_return(&__domain_nr);
> > +}
> > +#endif
> > +
> > /**
> > * pci_ext_cfg_avail - can we access extended PCI config space?
> > *
> > diff --git a/include/linux/of_pci.h b/include/linux/of_pci.h
> > index dde3a4a..71062e9 100644
> > --- a/include/linux/of_pci.h
> > +++ b/include/linux/of_pci.h
> > @@ -15,6 +15,7 @@ struct device_node *of_pci_find_child_device(struct device_node *parent,
> > int of_pci_get_devfn(struct device_node *np);
> > 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);
> > #else
> > static inline int of_irq_parse_pci(const struct pci_dev *pdev, struct of_phandle_args *out_irq)
> > {
> > @@ -43,6 +44,12 @@ of_pci_parse_bus_range(struct device_node *node, struct resource *res)
> > {
> > return -EINVAL;
> > }
> > +
> > +static inline int
> > +of_get_pci_domain_nr(struct device_node *node)
> > +{
> > + return -1;
> > +}
> > #endif
> >
> > #if defined(CONFIG_OF) && defined(CONFIG_PCI_MSI)
> > diff --git a/include/linux/pci.h b/include/linux/pci.h
> > index a494e5d..150da2d 100644
> > --- a/include/linux/pci.h
> > +++ b/include/linux/pci.h
> > @@ -1285,10 +1285,12 @@ void pci_cfg_access_unlock(struct pci_dev *dev);
> > */
> > #ifdef CONFIG_PCI_DOMAINS
> > extern int pci_domains_supported;
> > +int pci_get_new_domain_nr(void);
> > #else
> > enum { pci_domains_supported = 0 };
> > static inline int pci_domain_nr(struct pci_bus *bus) { return 0; }
> > static inline int pci_proc_domain(struct pci_bus *bus) { return 0; }
> > +static inline int pci_get_new_domain_nr(void) { return -ENOSYS; }
> > #endif /* CONFIG_PCI_DOMAINS */
> >
> > /*
> > @@ -1417,6 +1419,7 @@ static inline struct pci_dev *pci_get_bus_and_slot(unsigned int bus,
> >
> > static inline int pci_domain_nr(struct pci_bus *bus) { return 0; }
> > static inline struct pci_dev *pci_dev_get(struct pci_dev *dev) { return NULL; }
> > +static inline int pci_get_new_domain_nr(void) { return -ENOSYS; }
> >
> > #define dev_is_pci(d) (false)
> > #define dev_is_pf(d) (false)
> > --
> > 2.1.0
> >
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