Subject: Re: [PATCH v4 00/21] PowerPC/PowerNV: PCI Slot Management

From: Alexey Kardashevskiy <[email-masked]>
Date: Sat, 09 May 2015 09:59:25 +1000

On 05/01/2015 04:02 PM, Gavin Shan wrote:
> The series of patches intend to support PCI slot for PowerPC PowerNV platform,
> which is running on top of skiboot firmware. The patchset requires corresponding
> changes from skiboot firmware, which is sent to [email-masked]
> for review. The PCI slots are exposed by skiboot with device node properties,
> and kernel utilizes those properties to populated PCI slots accordingly.
>
> The original PCI infrastructure on PowerNV platform can't support hotplug
> because the PE is assigned during PHB fixup time, which is called for once
> during system boot time. For this, the PCI infrastructure on PowerNV platform
> has been reworked for a lot. After that, the PE and its corresponding resources
> (IODT, M32DT, M64 segments, DMA32 and bypass window) are assigned upon updating
> PCI bridge's resources, which might decide PE# assigned to the PE (e.g. M64
> resources, on P8 strictly speaking).

Out of curiosity - does this PCI scan happen when memory subsystem is 
initialized? More precisely, after these changes, won't 
pnv_pci_ioda2_setup_dma_pe() be called too early after boot so I won't be 
able to use kmalloc() to allocate iommu_table's?

Also, checkpatch.pl failed multiple times on the series. Please fix.

> Each PE will maintain a reference count,
> which is (number of child PCI devices + 1). That indicates when last child PCI
> device leaves the PE, the PE and its included resources will be relased and put
> back into free pool again. With this design, the PE will be released when EEH PE
> is released. PATCH[1 - 8] are related to this part.
>
>  From skiboot perspective, PCI slot is providing (hot/fundamental/complete)
> resets to EEH. The kernel gets to know if skiboot supports various reset on one
> particular PCI slot through device-tree node. If it does, EEH will utilize the
> functionality provided by skiboot. Besides, the device-tree nodes have to change
> in order to support PCI hotplug. For example, when one PCI adapter inserted to
> one slot, its device-tree node should be added to the system dynamically. Conversely,
> the device-tree node should be removed from the system when the PCI adapter is going
> to be offline. Since pci_dn and eeh_dev have same life cyle as PCI device nodes,
> they should be added/removed accordingly during PCI hotplug. Patch[9 - 20] are
> doing the related work.
>
> The last patch is the standalone PCI hotplug driver for PowerNV platform. When
> removing PCI adapter from one PCI slot, which is invoked by command in userland,
> the skiboot will power off the slot to save power and remove all device-tree
> nodes for all PCI devices behind the slot. Conversely, the Power to the slot
> is turned on, the PCI devices behind the slot is rescanned, and the device-tree
> nodes for those newly detected PCI devices will be built in skiboot. For both
> of cases, one message will be sent to kernel by skiboot so that the kernel
> can adjust the device-tree accordingly. At the same time, the kernel also have
> to deallocate or allocate PE# and its related resources (PE# and so on) for the
> removed/added PCI devices.
>
> Changelog
> =========
> v4:
>     * Rebased to 4.1.RC1
>     * Added API to unflatten FDT blob to device node sub-tree, which is attached
>       the indicated parent device node. The original mechanism based on formatted
>       string stream has been dropped.
>     * The PATCH[v3 09/21] ("powerpc/eeh: Delay probing EEH device during hotplug")
>       was picked up sent to linux-ppc@ separately for review as Richard's "VF EEH
>       Support" depends on that.
> v3:
>     * Rebased to 4.1.RC0
>     * PowerNV PCI infrasturcture is total refactored in order to support PCI
>       hotplug. The PowerNV hotplug driver is also reworked a lot because of
>       the changes in skiboot in order to support PCI hotplug.
>
> Gavin Shan (21):
>    pci: Add pcibios_setup_bridge()
>    powerpc/powernv: Enable M64 on P7IOC
>    powerpc/powernv: M64 support improvement
>    powerpc/powernv: Improve IO and M32 mapping
>    powerpc/powernv: Improve DMA32 segment assignment
>    powerpc/powernv: Create PEs dynamically
>    powerpc/powernv: Release PEs dynamically
>    powerpc/powernv: Drop pnv_ioda_setup_dev_PE()
>    powerpc/powernv: Use PCI slot reset infrastructure
>    powerpc/powernv: Fundamental reset for PCI bus reset
>    powerpc/pci: Don't scan empty slot
>    powerpc/pci: Move pcibios_find_pci_bus() around
>    powerpc/powernv: Introduce pnv_pci_poll()
>    powerpc/powernv: Functions to get/reset PCI slot status
>    powerpc/pci: Delay creating pci_dn
>    powerpc/pci: Create eeh_dev while creating pci_dn
>    powerpc/pci: Export traverse_pci_device_nodes()
>    powerpc/pci: Update bridge windows on PCI plugging
>    drivers/of: Support adding sub-tree
>    powerpc/powernv: Select OF_DYNAMIC
>    pci/hotplug: PowerPC PowerNV PCI hotplug driver
>
>   arch/powerpc/include/asm/eeh.h                 |    7 +-
>   arch/powerpc/include/asm/opal-api.h            |    7 +-
>   arch/powerpc/include/asm/opal.h                |    7 +-
>   arch/powerpc/include/asm/pci-bridge.h          |    7 +-
>   arch/powerpc/include/asm/pnv-pci.h             |    5 +
>   arch/powerpc/include/asm/ppc-pci.h             |    7 +-
>   arch/powerpc/kernel/eeh_dev.c                  |   20 +-
>   arch/powerpc/kernel/pci-common.c               |   18 +-
>   arch/powerpc/kernel/pci-hotplug.c              |   44 +-
>   arch/powerpc/kernel/pci_dn.c                   |  119 +-
>   arch/powerpc/platforms/maple/pci.c             |   35 +-
>   arch/powerpc/platforms/pasemi/pci.c            |    3 -
>   arch/powerpc/platforms/powermac/pci.c          |   39 +-
>   arch/powerpc/platforms/powernv/Kconfig         |    1 +
>   arch/powerpc/platforms/powernv/eeh-powernv.c   |  245 ++--
>   arch/powerpc/platforms/powernv/opal-wrappers.S |    3 +
>   arch/powerpc/platforms/powernv/pci-ioda.c      | 1657 +++++++++++++++---------
>   arch/powerpc/platforms/powernv/pci.c           |   64 +-
>   arch/powerpc/platforms/powernv/pci.h           |   52 +-
>   arch/powerpc/platforms/pseries/msi.c           |    4 +-
>   arch/powerpc/platforms/pseries/pci_dlpar.c     |   32 -
>   arch/powerpc/platforms/pseries/setup.c         |    9 +-
>   drivers/of/dynamic.c                           |   19 +-
>   drivers/of/fdt.c                               |  133 +-
>   drivers/pci/hotplug/Kconfig                    |   12 +
>   drivers/pci/hotplug/Makefile                   |    4 +
>   drivers/pci/hotplug/powernv_php.c              |  146 +++
>   drivers/pci/hotplug/powernv_php.h              |   78 ++
>   drivers/pci/hotplug/powernv_php_slot.c         |  643 +++++++++
>   drivers/pci/setup-bus.c                        |   12 +-
>   include/linux/of.h                             |    2 +
>   include/linux/of_fdt.h                         |    1 +
>   include/linux/pci.h                            |    1 +
>   33 files changed, 2473 insertions(+), 963 deletions(-)
>   create mode 100644 drivers/pci/hotplug/powernv_php.c
>   create mode 100644 drivers/pci/hotplug/powernv_php.h
>   create mode 100644 drivers/pci/hotplug/powernv_php_slot.c
>

-- 
Alexey