From: Jiang Liu <liuj97@gmail.com>
To: Bjorn Helgaas <bhelgaas@google.com>
Cc: Jiang Liu <jiang.liu@huawei.com>,
"Rafael J . Wysocki" <rjw@sisk.pl>,
Yijing Wang <wangyijing@huawei.com>,
linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org,
Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Subject: Re: [PATCH v2] PCI: allow acpiphp to handle PCIe ports w/o native PCIe hotplug capability
Date: Tue, 25 Sep 2012 23:16:06 +0800 [thread overview]
Message-ID: <5061CAB6.306@gmail.com> (raw)
In-Reply-To: <CAErSpo5gyZgxWxwTgXRMyZzDDbEBeXHtmhisPN2FqvvUarmTeg@mail.gmail.com>
On 09/25/2012 06:10 AM, Bjorn Helgaas wrote:
> On Wed, Aug 22, 2012 at 9:16 AM, Jiang Liu <liuj97@gmail.com> wrote:
>> From: Jiang Liu <jiang.liu@huawei.com>
>>
>> Commit 0d52f54e2ef64c189dedc332e680b2eb4a34590a (PCI / ACPI: Make acpiphp
>> ignore root bridges using PCIe native hotplug) added code that made the
>> acpiphp driver completely ignore PCIe root complexes for which the kernel
>> had been granted control of the native PCIe hotplug feature by the BIOS
>> through _OSC. Later commit 619a5182d1f38a3d629ee48e04fa182ef9170052
>> "PCI hotplug: Always allow acpiphp to handle non-PCIe bridges" relaxed
>> the constraints to allow acpiphp driver handle non-PCIe bridges under
>> such a complex. The constraint needs to be relaxed further to allow
>> acpiphp driver to hanlde PCIe ports without native PCIe hotplug capability.
>>
>> Some MR-IOV switch chipsets, such PLX8696, support multiple virtual PCIe
>> switches and may migrate downstream ports among virtual switches.
>> To migrate a downstream port from the source virtual switch to the target,
>> the port needs to be hot-removed from the source and hot-added into the
>> target. pciehp driver can't be used here because there's no slots within
>> the virtual PCIe switch. So acpiphp driver is used to support downstream
>> port migration. A typical configuration is as below:
>> [Root w/o native PCIe HP]
>> [Upstream port of vswitch w/o native PCIe HP]
>> [Downstream port of vswitch w/ native PCIe HP]
>> [PCIe enpoint]
>>
>> Here acpiphp driver will be used to handle root ports and upstream port
>> in the virtual switch, and pciehp driver will be used to handle downstream
>> ports in the virtual switch.
>>
>> v1->v2: use PCIe capability accessors to read PCI_EXP_SLTCAP register
>>
>> Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
>> Signed-off-by: Jiang Liu <liuj97@gmail.com>
>
> I tweaked the changelog (typos, indentation) and applied this to my
> "pci/jiang-acpiphp" branch. Kenji acked a previous version, but I
> didn't add it here because this is slightly updated.
>
> If the PLX8696 supports moving downstream ports between upstream
> ports, it seems like a deficiency if the upstream port doesn't support
> native hotplug. If I understand correctly, this patch allows the use
> of acpiphp for "hotplug" of the downstream ports, but that is only an
> option if the PLX8696 is in the ACPI namespace.
>
> It seems like the lack of PLX8696 native hotplug for upstream ports
> mean this virtual switch migration can only be done if the PLX8696 is
> soldered into the system -- for instance, we don't have any way to
> deal with an 8696 on a plug-in card because ACPI won't know anything
> about that device.
Hi Bjorn,
That's true, we can't deal with 8696 on add-in cards yet. The platform
we are working with is:
The motherboard has a specially designed slot for a root port, which
could only be used to connect an IO-extension box with 8696. So the BIOS could
build ACPI objects for the 8696 chipset.
Thanks!
Gerry
prev parent reply other threads:[~2012-09-25 15:16 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-04 7:44 [Resend with Ack][PATCH v1] PCI: allow acpiphp to handle PCIe ports without native PCIe hotplug capability Jiang Liu
2012-06-04 8:23 ` Kenji Kaneshige
2012-07-03 4:16 ` Bjorn Helgaas
2012-07-03 15:59 ` Bjorn Helgaas
2012-07-03 19:50 ` Don Dutile
2012-07-04 18:07 ` Bjorn Helgaas
2012-07-09 10:05 ` Jiang Liu
2012-07-09 17:05 ` Bjorn Helgaas
2012-07-04 2:52 ` Jiang Liu
2012-07-10 15:54 ` [RFC PATCH 00/14] improve PCIe capabilities registers handling Jiang Liu
2012-07-10 18:44 ` Bjorn Helgaas
2012-07-10 15:54 ` [RFC PATCH 01/14] PCI: add pcie_flags into struct pci_dev to cache PCIe capabilities register Jiang Liu
2012-07-11 9:01 ` Taku Izumi
2012-07-11 14:27 ` Jiang Liu
2012-07-10 15:54 ` [RFC PATCH 02/14] PCI: introduce pci_pcie_type(dev) to replace pci_dev->pcie_type Jiang Liu
2012-07-10 15:54 ` [RFC PATCH 03/14] PCI: remove unused field pcie_type from struct pci_dev Jiang Liu
2012-07-10 15:54 ` [RFC PATCH 04/14] PCI: refine and move pcie_cap_has_*() macros to include/linux/pci.h Jiang Liu
2012-07-10 18:49 ` Bjorn Helgaas
2012-07-10 15:54 ` [RFC PATCH 05/14] PCI: add access functions for PCIe capabilities to hide PCIe spec differences Jiang Liu
2012-07-10 18:35 ` Bjorn Helgaas
2012-07-11 3:07 ` Jiang Liu
2012-07-11 3:40 ` Bjorn Helgaas
2012-07-11 6:40 ` Jiang Liu
2012-07-11 17:52 ` Bjorn Helgaas
2012-07-12 2:56 ` Jiang Liu
2012-07-12 20:49 ` Bjorn Helgaas
2012-07-15 16:47 ` Jiang Liu
2012-07-16 17:29 ` Bjorn Helgaas
2012-07-16 18:57 ` Don Dutile
2012-07-17 0:09 ` Jiang Liu
2012-07-17 0:14 ` Bjorn Helgaas
2012-07-10 15:54 ` [RFC PATCH 06/14] PCI: use PCIe cap access functions to simplify PCI core implementation Jiang Liu
2012-07-10 18:35 ` Bjorn Helgaas
2012-07-11 2:49 ` Jiang Liu
2012-07-10 15:54 ` [RFC PATCH 07/14] hotplug/PCI: use PCIe cap access functions to simplify implementation Jiang Liu
2012-07-10 18:35 ` Bjorn Helgaas
2012-07-10 15:54 ` [RFC PATCH 08/14] portdrv/PCI: " Jiang Liu
2012-07-10 15:54 ` [RFC PATCH 09/14] pciehp/PCI: " Jiang Liu
2012-07-10 15:54 ` [RFC PATCH 10/14] PME/PCI: " Jiang Liu
2012-07-10 15:54 ` [RFC PATCH 11/14] AER/PCI: " Jiang Liu
2012-07-10 15:54 ` [RFC PATCH 12/14] ASPM/PCI: " Jiang Liu
2012-07-10 15:54 ` [RFC PATCH 13/14] r8169/PCI: " Jiang Liu
2012-07-10 15:54 ` [RFC PATCH 14/14] qib/PCI: " Jiang Liu
2012-08-15 19:12 ` [Resend with Ack][PATCH v1] PCI: allow acpiphp to handle PCIe ports without native PCIe hotplug capability Bjorn Helgaas
2012-08-16 15:15 ` Jiang Liu
2012-08-22 15:16 ` [PATCH v2] PCI: allow acpiphp to handle PCIe ports w/o " Jiang Liu
2012-09-24 22:10 ` Bjorn Helgaas
2012-09-25 15:16 ` Jiang Liu [this message]
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