Re: [PATCH v1 00/25] PCI: Request host bridge window resources

[wangyijing <wangyijing@huawei.com>]

Hi Bjorn, use devm_request_resource() for host bridge resource is cool,
what about do the similar change for x86, now we request host bridge resource
in pci_acpi_root_add_resources() in x86, and we would release the host bridge
resource when host bridge device refcount reach 0. This logic may introduce issue,
E.g.
If we try to remove a pci host bridge, but there is a child pci device which refcount
cannot decrease to 0 after remove the device, in this case, its parent pci_bus and
parent device, all their refcount cannot reach to 0, the result is pci host bridge
refcount can not reach 0, so its .release_fn() won't be called, and host bridge
resouces can not release. If we want to add the pci host bridge again, all pci devices
can not work because the resource is conflict with the old.

devm resource would be released when the driver detach, this is better than what we do now, I think.

Thanks!
Yijing.

在 2016/6/19 2:07, Bjorn Helgaas 写道:
> On Mon, Jun 06, 2016 at 06:04:44PM -0500, Bjorn Helgaas wrote:
>> Several host bridge drivers (designware and all derivatives, iproc,
>> xgene, xilinx, and xilinx-nwl) don't request the MMIO and I/O port
>> windows they forward downstream to the PCI bus.
>>
>> That means the PCI core can't request resources for PCI bridge
>> windows and PCI BARs.
>>
>> Several other drivers (altera, generic, mvebu, rcar, tegra) do request
>> the windows, but use some duplicated code to do it.
>>
>> This adds a new devm_request_pci_bus_resources() interface and changes
>> these drivers to use it.  It also fixes several error paths where we failed
>> to free the resource list allocated by of_pci_get_host_bridge_resources().
>>
>> Tegra guys, please take a look at "PCI: tegra: Remove top-level resource
>> from hierarchy" in particular.  Removing the top-level resource definitely
>> makes /proc/iomem look uglier (although it will look more like that of
>> other drivers).  A short-term fix could be to include device information in
>> the resource name.  I think a better long-term fix would be to make the DT
>> or platform device core request all the resources from the DT.
>>
>> Comments welcome.  I expect we'll trip over something here, so I marked
>> this "v1" and I don't plan to put it into -next for a while.
>>
>> This is on my pci/host-request-windows branch, which you can pull or view
>> at https://git.kernel.org/cgit/linux/kernel/git/helgaas/pci.git/log/?h=pci/host-request-windows
> 
> I merged this to my -next branch, so it should show up in linux-next
> in a couple days.  Let me know if you see any problems.
> 
>> Bjorn Helgaas (25):
>>       PCI: Add devm_request_pci_bus_resources()
>>       PCI: designware: Free bridge resource list on failure
>>       PCI: designware: Request host bridge window resources
>>       PCI: designware: Simplify host bridge window iteration
>>       PCI: iproc: Request host bridge window resources
>>       PCI: xgene: Free bridge resource list on failure
>>       PCI: xgene: Request host bridge window resources
>>       PCI: xilinx: Free bridge resource list on failure
>>       PCI: xilinx: Request host bridge window resources
>>       PCI: xilinx-nwl: Free bridge resource list on failure
>>       PCI: xilinx-nwl: Request host bridge window resources
>>       PCI: xilinx-nwl: Use dev_printk() when possible
>>       PCI: altera: Request host bridge window resources with core function
>>       PCI: altera: Simplify host bridge window iteration
>>       PCI: generic: Free resource list close to where it's allocated
>>       PCI: generic: Request host bridge window resources with core function
>>       PCI: generic: Simplify host bridge window iteration
>>       PCI: mvebu: Request host bridge window resources with core function
>>       PCI: rcar Gen2: Request host bridge window resources
>>       PCI: rcar: Request host bridge window resources with core function
>>       PCI: rcar: Simplify host bridge window iteration
>>       PCI: tegra: Remove top-level resource from hierarchy
>>       PCI: tegra: Request host bridge window resources with core function
>>       PCI: versatile: Request host bridge window resources with core function
>>       PCI: versatile: Simplify host bridge window iteration
>>
>>
>>  drivers/pci/bus.c                  |   29 +++++++++++++++++
>>  drivers/pci/host/pci-host-common.c |   61 +++++++++++++++---------------------
>>  drivers/pci/host/pci-mvebu.c       |   17 ++++------
>>  drivers/pci/host/pci-rcar-gen2.c   |    4 ++
>>  drivers/pci/host/pci-tegra.c       |   35 +++------------------
>>  drivers/pci/host/pci-versatile.c   |   29 ++++++-----------
>>  drivers/pci/host/pci-xgene.c       |   16 ++++++++-
>>  drivers/pci/host/pcie-altera.c     |   35 ++++++---------------
>>  drivers/pci/host/pcie-designware.c |   34 +++++++++++++-------
>>  drivers/pci/host/pcie-iproc.c      |    4 ++
>>  drivers/pci/host/pcie-rcar.c       |   33 +++++--------------
>>  drivers/pci/host/pcie-xilinx-nwl.c |   20 +++++++++---
>>  drivers/pci/host/pcie-xilinx.c     |   16 ++++++++-
>>  include/linux/pci.h                |    5 ++-
>>  14 files changed, 170 insertions(+), 168 deletions(-)
>>
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