On Tue, Jul 08, 2014 at 01:59:54AM +0100, Bjorn Helgaas wrote:

On Tue, Jul 01, 2014 at 07:43:31PM +0100, Liviu Dudau wrote:

quoted

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.

Yes, I'm coming to the same conclusion. :)

quoted

Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>
Tested-by: Tanmay Inamdar <redacted>
---
 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

I will try to propose a patch implementing this.

Best regards,
Liviu

quoted

 {
 	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

-- 
====================
| I would like to |
| fix the world,  |
| but they're not |
| giving me the   |
 \ source code!  /
  ---------------
    ?\_(?)_/?