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Message-ID: <20140708005954.GC22939@google.com>
Date: Mon, 7 Jul 2014 18:59:54 -0600
From: Bjorn Helgaas <bhelgaas@...gle.com>
To: Liviu Dudau <Liviu.Dudau@....com>
Cc: linux-pci <linux-pci@...r.kernel.org>,
Catalin Marinas <Catalin.Marinas@....com>,
Will Deacon <Will.Deacon@....com>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Arnd Bergmann <arnd@...db.de>,
linaro-kernel <linaro-kernel@...ts.linaro.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>,
LKML <linux-kernel@...r.kernel.org>,
Device Tree ML <devicetree@...r.kernel.org>,
LAKML <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v8 6/9] pci: Introduce a domain number for
pci_host_bridge.
On Tue, Jul 01, 2014 at 07:43:31PM +0100, Liviu Dudau wrote:
> Make it easier to discover the domain number of a bus by storing
> the number in pci_host_bridge for the root bus. Several architectures
> have their own way of storing this information, so it makes sense
> to try to unify the code. While at this, add a new function that
> creates a root bus in a given domain and make pci_create_root_bus()
> a wrapper around this function.
"While at this" is always a good clue that maybe something should be
split into a separate patch :) This is a very good example, since it
adds a new interface that deserves its own changelog.
> Signed-off-by: Liviu Dudau <Liviu.Dudau@....com>
> Tested-by: Tanmay Inamdar <tinamdar@....com>
> ---
> drivers/pci/probe.c | 41 +++++++++++++++++++++++++++++++++--------
> include/linux/pci.h | 4 ++++
> 2 files changed, 37 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 2c92662..abf5e82 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -1748,8 +1748,9 @@ void __weak pcibios_remove_bus(struct pci_bus *bus)
> {
> }
>
> -struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
> - struct pci_ops *ops, void *sysdata, struct list_head *resources)
> +struct pci_bus *pci_create_root_bus_in_domain(struct device *parent,
> + int domain, int bus, struct pci_ops *ops, void *sysdata,
> + struct list_head *resources)
I don't think we should do it this way; this makes it possible to have a
host bridge where "bridge->domain_nr != pci_domain_nr(bridge->bus)".
I wonder if it would help to make a weak pci_domain_nr() function that
returns "bridge->domain_nr". Then each arch could individually drop its
pci_domain_nr() definition as it was converted, e.g., something like this:
- Convert every arch pci_domain_nr() from a #define to a non-inline
function
- Add bridge.domain_nr, initialized from pci_domain_nr()
- Add a weak generic pci_domain_nr() that returns bridge.domain_nr
- Add a way to create a host bridge in a specified domain, so we can
initialize bridge.domain_nr without using pci_domain_nr()
- Convert each arch to use the new creation mechanism and drop its
pci_domain_nr() implementation
> {
> int error;
> struct pci_host_bridge *bridge;
> @@ -1762,27 +1763,31 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
>
> bridge = pci_alloc_host_bridge();
> if (!bridge)
> - return NULL;
> + return ERR_PTR(-ENOMEM);
>
> bridge->dev.parent = parent;
> bridge->dev.release = pci_release_host_bridge_dev;
> + bridge->domain_nr = domain;
>
> b = pci_alloc_bus();
> - if (!b)
> + if (!b) {
> + error = -ENOMEM;
> goto err_out;
> + }
>
> b->sysdata = sysdata;
> b->ops = ops;
> b->number = b->busn_res.start = bus;
> - b2 = pci_find_bus(pci_domain_nr(b), bus);
> + b2 = pci_find_bus(bridge->domain_nr, bus);
> if (b2) {
> /* If we already got to this bus through a different bridge, ignore it */
> dev_dbg(&b2->dev, "bus already known\n");
> + error = -EEXIST;
> goto err_bus_out;
> }
>
> bridge->bus = b;
> - dev_set_name(&bridge->dev, "pci%04x:%02x", pci_domain_nr(b), bus);
> + dev_set_name(&bridge->dev, "pci%04x:%02x", bridge->domain_nr, bus);
> error = pcibios_root_bridge_prepare(bridge);
> if (error)
> goto err_out;
> @@ -1801,7 +1806,7 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
>
> b->dev.class = &pcibus_class;
> b->dev.parent = b->bridge;
> - dev_set_name(&b->dev, "%04x:%02x", pci_domain_nr(b), bus);
> + dev_set_name(&b->dev, "%04x:%02x", bridge->domain_nr, bus);
> error = device_register(&b->dev);
> if (error)
> goto class_dev_reg_err;
> @@ -1851,7 +1856,27 @@ err_bus_out:
> kfree(b);
> err_out:
> kfree(bridge);
> - return NULL;
> + return ERR_PTR(error);
> +}
> +
> +struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
> + struct pci_ops *ops, void *sysdata, struct list_head *resources)
> +{
> + int domain_nr;
> + struct pci_bus *b = pci_alloc_bus();
> + if (!b)
> + return NULL;
> +
> + b->sysdata = sysdata;
> + domain_nr = pci_domain_nr(b);
> + kfree(b);
> +
> + b = pci_create_root_bus_in_domain(parent, domain_nr, bus,
> + ops, sysdata, resources);
> + if (IS_ERR(b))
> + return NULL;
> +
> + return b;
> }
>
> int pci_bus_insert_busn_res(struct pci_bus *b, int bus, int bus_max)
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 466bcd1..7e7b939 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -401,6 +401,7 @@ struct pci_host_bridge_window {
> struct pci_host_bridge {
> struct device dev;
> struct pci_bus *bus; /* root bus */
> + int domain_nr;
> struct list_head windows; /* pci_host_bridge_windows */
> void (*release_fn)(struct pci_host_bridge *);
> void *release_data;
> @@ -769,6 +770,9 @@ struct pci_bus *pci_scan_bus(int bus, struct pci_ops *ops, void *sysdata);
> struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
> struct pci_ops *ops, void *sysdata,
> struct list_head *resources);
> +struct pci_bus *pci_create_root_bus_in_domain(struct device *parent,
> + int domain, int bus, struct pci_ops *ops,
> + void *sysdata, struct list_head *resources);
> int pci_bus_insert_busn_res(struct pci_bus *b, int bus, int busmax);
> int pci_bus_update_busn_res_end(struct pci_bus *b, int busmax);
> void pci_bus_release_busn_res(struct pci_bus *b);
> --
> 2.0.0
>
--
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