From: bhelgaas@google.com (Bjorn Helgaas)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v6 06/30] PCI: Combine PCI domain and bus number in u32 arg
Date: Thu, 12 Mar 2015 14:49:27 -0500 [thread overview]
Message-ID: <20150312194927.GC7346@google.com> (raw)
In-Reply-To: <55018330.5050002@huawei.com>
On Thu, Mar 12, 2015 at 08:14:40PM +0800, Yijing Wang wrote:
> On 2015/3/12 9:29, Bjorn Helgaas wrote:
> > 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.
>
> Sorry for my poor description for this patch, I combined the domain and bus, because
> I think now we have too many args at pci_scan_root_bus() or other scan functions,
>
> struct pci_bus *pci_scan_root_bus(struct device *parent, int bus,
> struct pci_ops *ops, void *sysdata, struct list_head *resources)
>
> Now we have five args yet, plus the new introduced domain and pci_host_bridge_ops,
> it will become 7.
>
> I thought introduced a new structure which contain the necessary info to scan root bus/ host bridge,
>
> E.g
>
> struct pci_scan_info {
> int bus;
> struct device *parent;
> struct pci_ops *ops;
> void *sysdata;
> struct list_head *resource;
> int domain;
> struct pci_host_bridge_ops;
> }
>
> Do you like this one or keep it like now ?
>
> pci_scan_root_bus(struct device *parent, int domain, int bus,
> struct pci_ops *ops, void *sysdata, struct list_head *resources, struct pci_host_bridge_ops *ops)
I don't think reducing the number of arguments is a good argument for
squashing some of them together.
I don't really want to add a structure like that because it adds management
complexity for all the callers because it contains per-bridge things (bus,
parent, domain, resource, sysdata). Things like struct pci_ops and struct
pci_host_bridge_ops are much simpler because drivers can statically
allocate a single copy and use it for multiple devices.
I think it might make sense to put the struct pci_ops pointer inside struct
pci_host_bridge_ops. That would get rid of one of the arguments.
You might also be able to get rid of the "bus" argument, since the caller
should be passing an IORESOURCE_BUS resource in the resource list, and
"bus" should be the same as res->start.
Bjorn
next prev parent reply other threads:[~2015-03-12 19:49 UTC|newest]
Thread overview: 87+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-09 2:33 [PATCH v6 00/30] Refine PCI scan interfaces and make generic pci host bridge Yijing Wang
2015-03-09 2:33 ` [PATCH v6 01/30] PCI: Rip out pci_bus_add_devices() from pci_scan_bus() Yijing Wang
2015-03-09 2:33 ` [PATCH v6 02/30] PCI: Rip out pci_bus_add_devices() from pci_scan_root_bus() Yijing Wang
2015-03-09 2:34 ` [PATCH v6 03/30] PCI: Export busn_resource to drivers/pci Yijing Wang
2015-03-11 22:28 ` Bjorn Helgaas
2015-03-12 11:42 ` Yijing Wang
2015-03-12 19:32 ` Bjorn Helgaas
2015-03-13 1:57 ` Yijing Wang
2015-03-09 2:34 ` [PATCH v6 04/30] xen/PCI: Don't use deprecated function pci_scan_bus_parented() Yijing Wang
2015-03-11 22:32 ` Bjorn Helgaas
2015-03-12 11:46 ` Yijing Wang
2015-03-12 19:35 ` Bjorn Helgaas
2015-03-13 2:36 ` Yijing Wang
2015-03-13 13:24 ` Bjorn Helgaas
2015-03-13 14:01 ` Konrad Rzeszutek Wilk
2015-03-13 14:26 ` Bjorn Helgaas
2015-03-25 19:23 ` Konrad Rzeszutek Wilk
2015-03-26 1:18 ` Yijing Wang
2015-03-26 7:30 ` Yijing Wang
2015-03-09 2:34 ` [PATCH v6 05/30] PCI: Remove deprecated pci_scan_bus_parented() Yijing Wang
2015-03-09 2:34 ` [PATCH v6 06/30] PCI: Combine PCI domain and bus number in u32 arg Yijing Wang
2015-03-12 1:29 ` Bjorn Helgaas
2015-03-12 12:14 ` Yijing Wang
2015-03-12 19:49 ` Bjorn Helgaas [this message]
2015-03-13 3:19 ` Yijing Wang
2015-03-09 2:34 ` [PATCH v6 07/30] PCI: Pass PCI domain number combined with root bus number Yijing Wang
2015-03-12 1:34 ` Bjorn Helgaas
2015-03-12 12:20 ` Yijing Wang
2015-03-17 5:15 ` [Xen-devel] " Manish Jaggi
2015-03-17 14:05 ` Ian Campbell
2015-03-09 2:34 ` [PATCH v6 08/30] PCI: Introduce pci_host_assign_domain_nr() to assign domain Yijing Wang
2015-03-12 1:39 ` Bjorn Helgaas
2015-03-12 12:23 ` Yijing Wang
2015-03-09 2:34 ` [PATCH v6 09/30] PCI: Separate pci_host_bridge creation out of pci_create_root_bus() Yijing Wang
2015-03-12 3:52 ` Bjorn Helgaas
2015-03-12 13:44 ` Yijing Wang
2015-03-21 23:21 ` Suravee Suthikulpanit
2015-03-23 1:08 ` Yijing Wang
2015-03-09 2:34 ` [PATCH v6 10/30] PCI: Introduce pci_host_bridge_list to manage host bridges Yijing Wang
2015-03-12 2:55 ` Bjorn Helgaas
2015-03-12 13:03 ` Yijing Wang
2015-03-12 19:56 ` Bjorn Helgaas
2015-03-13 3:28 ` Yijing Wang
2015-03-13 14:33 ` Bjorn Helgaas
2015-03-16 1:28 ` Yijing Wang
2015-03-09 2:34 ` [PATCH v6 11/30] PCI: Save sysdata in pci_host_bridge drvdata Yijing Wang
2015-03-09 2:34 ` [PATCH v6 12/30] PCI: Introduce pci_host_bridge_ops to support host specific operations Yijing Wang
2015-03-12 3:23 ` Bjorn Helgaas
2015-03-12 13:14 ` Yijing Wang
2015-03-09 2:34 ` [PATCH v6 13/30] PCI: Introduce new scan function pci_scan_host_bridge() Yijing Wang
2015-03-12 3:25 ` Bjorn Helgaas
2015-03-12 13:15 ` Yijing Wang
2015-03-09 2:34 ` [PATCH v6 14/30] x86/PCI: Refine pci_acpi_scan_root() with generic pci_host_bridge Yijing Wang
2015-03-09 2:34 ` [PATCH v6 15/30] ia64/PCI: " Yijing Wang
2015-03-09 2:34 ` [PATCH v6 16/30] powerpc/pci: Rename pcibios_root_bridge_prepare() Yijing Wang
2015-03-09 2:34 ` [PATCH v6 17/30] powerpc/pci: Use pci_scan_host_bridge() for simplicity Yijing Wang
2015-03-09 2:34 ` [PATCH v6 18/30] PCI: Remove weak pcibios_root_bridge_prepare() Yijing Wang
2015-03-09 2:34 ` [PATCH v6 19/30] sparc/PCI: Claim bus resources before pci_bus_add_devices() Yijing Wang
2015-03-09 2:34 ` [PATCH v6 20/30] sparc/PCI: Use pci_scan_host_bridge() for simplicity Yijing Wang
2015-03-12 3:30 ` Bjorn Helgaas
2015-03-12 13:17 ` Yijing Wang
2015-03-09 2:34 ` [PATCH v6 21/30] PCI: Introduce pci_bus_child_max_busnr() Yijing Wang
2015-03-12 3:33 ` Bjorn Helgaas
2015-03-12 13:24 ` Yijing Wang
2015-03-12 3:36 ` Bjorn Helgaas
2015-03-12 13:28 ` Yijing Wang
2015-03-12 20:00 ` Bjorn Helgaas
2015-03-09 2:34 ` [PATCH v6 22/30] parisc/PCI: Use pci_scan_root_bus() for simplicity Yijing Wang
2015-03-09 2:34 ` [PATCH v6 23/30] PCI/mvebu: Use pci_common_init_dev() to simplify code Yijing Wang
2015-03-09 2:34 ` [PATCH v6 24/30] PCI/tegra: Remove redundant tegra_pcie_scan_bus() Yijing Wang
2015-03-09 2:34 ` [PATCH v6 25/30] PCI/designware: Use pci_scan_root_bus() for simplicity Yijing Wang
2015-03-09 2:34 ` [PATCH v6 26/30] PCI/xgene: Use pci_scan_root_bus() instead of pci_create_root_bus() Yijing Wang
2015-03-09 2:34 ` [PATCH v6 27/30] PCI: Rename __pci_create_root_bus() to pci_create_root_bus() Yijing Wang
2015-03-09 2:34 ` [PATCH v6 28/30] PCI: Export find_pci_host_bridge() and rename to pci_find_host_bridge() Yijing Wang
2015-03-12 3:43 ` Bjorn Helgaas
2015-03-12 13:29 ` Yijing Wang
2015-03-09 2:34 ` [PATCH v6 29/30] PCI: Remove platform specific pci_domain_nr() Yijing Wang
2015-03-09 2:34 ` [PATCH v6 30/30] PCI: Remove pci_bus_assign_domain_nr() Yijing Wang
2015-03-12 3:48 ` Bjorn Helgaas
2015-03-12 13:32 ` Yijing Wang
2015-03-12 21:23 ` [PATCH v6 00/30] Refine PCI scan interfaces and make generic pci host bridge Bjorn Helgaas
2015-03-13 3:29 ` Yijing Wang
2015-03-13 11:31 ` Liviu Dudau
2015-03-13 14:48 ` Bjorn Helgaas
2015-03-16 1:31 ` Yijing Wang
2015-03-16 1:48 ` Yijing Wang
2015-03-17 10:55 ` Liviu Dudau
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