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SubjectRe: [PATCH v6 06/30] PCI: Combine PCI domain and bus number in u32 arg
On Mon, Mar 09, 2015 at 10:34:03AM +0800, Yijing Wang wrote:
> Currently, we use int type for bus number in
> pci_create_root_bus(), pci_scan_root_bus() and
> pci_scan_bus_legacy. Because PCI bus number
> always <= 255, so we could change the bus number
> argument type to u32, and combine PCI domain and
> bus number in one.

This makes no sense. Or rather, it only states the obvious: an 8-bit value
and a 16-bit value will both fit in a 32-bit value. But it doesn't say
*why* you think it's a good idea to pass a single value that contains both
domain and bus numbers. The obvious thing is to pass two separate values,
and you don't say why passing a single combined value is better.

Also see whitespace mistakes below. I get a little testy when people don't
follow the whitespace convention of neighboring lines because if people are
sloppy about whitespace I assume they're sloppy about the code.

> Also add a domain member in
> pci_host_bridge to save domain number. Finally,
> we could eliminate lots of the platform specific
> pci_domain_nr() in the last of the series.
>
> Signed-off-by: Yijing Wang <wangyijing@huawei.com>
> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
> ---
> drivers/pci/probe.c | 16 +++++++++-------
> include/linux/pci.h | 7 ++++---
> include/uapi/linux/pci.h | 3 +++
> 3 files changed, 16 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 187fa54..3d6befd 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -1890,7 +1890,7 @@ void __weak pcibios_remove_bus(struct pci_bus *bus)
> {
> }
>
> -struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
> +struct pci_bus *pci_create_root_bus(struct device *parent, u32 db,
> struct pci_ops *ops, void *sysdata, struct list_head *resources)
> {
> int error;
> @@ -1901,6 +1901,7 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
> resource_size_t offset;
> char bus_addr[64];
> char *fmt;
> + u8 bus = PCI_BUSNUM(db);

Whitespace botch.

>
> b = pci_alloc_bus(NULL);
> if (!b)
> @@ -1921,6 +1922,7 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
> if (!bridge)
> goto err_out;
>
> + bridge->domain = PCI_DOMAIN(db);
> bridge->dev.parent = parent;
> bridge->dev.release = pci_release_host_bridge_dev;
> dev_set_name(&bridge->dev, "pci%04x:%02x", pci_domain_nr(b), bus);
> @@ -2058,7 +2060,7 @@ void pci_bus_release_busn_res(struct pci_bus *b)
> res, ret ? "can not be" : "is");
> }
>
> -struct pci_bus *pci_scan_root_bus(struct device *parent, int bus,
> +struct pci_bus *pci_scan_root_bus(struct device *parent, u32 db,
> struct pci_ops *ops, void *sysdata, struct list_head *resources)
> {
> struct resource_entry *window;
> @@ -2072,15 +2074,15 @@ struct pci_bus *pci_scan_root_bus(struct device *parent, int bus,
> break;
> }
>
> - b = pci_create_root_bus(parent, bus, ops, sysdata, resources);
> + b = pci_create_root_bus(parent, db, ops, sysdata, resources);
> if (!b)
> return NULL;
>
> if (!found) {
> dev_info(&b->dev,
> "No busn resource found for root bus, will use [bus %02x-ff]\n",
> - bus);
> - pci_bus_insert_busn_res(b, bus, 255);
> + PCI_BUSNUM(db));
> + pci_bus_insert_busn_res(b, PCI_BUSNUM(db), 255);
> }
>
> max = pci_scan_child_bus(b);
> @@ -2092,7 +2094,7 @@ struct pci_bus *pci_scan_root_bus(struct device *parent, int bus,
> }
> EXPORT_SYMBOL(pci_scan_root_bus);
>
> -struct pci_bus *pci_scan_bus(int bus, struct pci_ops *ops,
> +struct pci_bus *pci_scan_bus(u32 db, struct pci_ops *ops,
> void *sysdata)
> {
> LIST_HEAD(resources);
> @@ -2101,7 +2103,7 @@ struct pci_bus *pci_scan_bus(int bus, struct pci_ops *ops,
> pci_add_resource(&resources, &ioport_resource);
> pci_add_resource(&resources, &iomem_resource);
> pci_add_resource(&resources, &busn_resource);
> - b = pci_create_root_bus(NULL, bus, ops, sysdata, &resources);
> + b = pci_create_root_bus(NULL, db, ops, sysdata, &resources);
> if (b) {
> pci_scan_child_bus(b);
> } else {
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 36effb8..8b3d245 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -401,6 +401,7 @@ static inline int pci_channel_offline(struct pci_dev *pdev)
> }
>
> struct pci_host_bridge {
> + u16 domain;

Please follow the existing whitespace convention, i.e., use a space, not a
tab, between "u16 domain".

> struct device dev;
> struct pci_bus *bus; /* root bus */
> struct list_head windows; /* resource_entry */
> @@ -769,14 +770,14 @@ void pcibios_bus_to_resource(struct pci_bus *bus, struct resource *res,
> void pcibios_scan_specific_bus(int busn);
> struct pci_bus *pci_find_bus(int domain, int busnr);
> void pci_bus_add_devices(const struct pci_bus *bus);
> -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_bus *pci_scan_bus(u32 dombus, struct pci_ops *ops, void *sysdata);
> +struct pci_bus *pci_create_root_bus(struct device *parent, u32 dombus,
> 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);
> -struct pci_bus *pci_scan_root_bus(struct device *parent, int bus,
> +struct pci_bus *pci_scan_root_bus(struct device *parent, u32 dombus,
> struct pci_ops *ops, void *sysdata,
> struct list_head *resources);
> struct pci_bus *pci_add_new_bus(struct pci_bus *parent, struct pci_dev *dev,
> diff --git a/include/uapi/linux/pci.h b/include/uapi/linux/pci.h
> index 3c292bc..89c6f15 100644
> --- a/include/uapi/linux/pci.h
> +++ b/include/uapi/linux/pci.h
> @@ -30,6 +30,9 @@
> #define PCI_DEVFN(slot, func) ((((slot) & 0x1f) << 3) | ((func) & 0x07))
> #define PCI_SLOT(devfn) (((devfn) >> 3) & 0x1f)
> #define PCI_FUNC(devfn) ((devfn) & 0x07)
> +#define PCI_DOMAIN(db) ((db) >> 16)
> +#define PCI_BUSNUM(db) ((db) & 0xffff)
> +#define PCI_DOMBUS(domain, bus) (((domain) << 16) | (bus))
>
> /* Ioctls for /proc/bus/pci/X/Y nodes. */
> #define PCIIOC_BASE ('P' << 24 | 'C' << 16 | 'I' << 8)
> --
> 1.7.1
>
> --
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