Re: [PATCH V6 08/13] PCI: generic, thunder: update to use generic ECAM API

From	Tomasz Nowicki <tn@semihalf.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH V6 08/13] PCI: generic, thunder: update to use generic ECAM API
Date	2016-04-18 15:10 +0200
Message-ID	<rph6a-69y-7@gated-at.bofh.it> (permalink)
References	<rofpL-6tr-1@gated-at.bofh.it> <rogYy-7wu-17@gated-at.bofh.it> <rosQ1-8hF-5@gated-at.bofh.it> <rosZI-8lb-7@gated-at.bofh.it> <rozya-4VT-31@gated-at.bofh.it>
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On 16.04.2016 16:36, Jayachandran C wrote:
> On Sat, Apr 16, 2016 at 1:01 PM, Arnd Bergmann <arnd@arndb.de> wrote:
>> On Saturday 16 April 2016 12:50:13 Jayachandran C wrote:
>>>>
>>>> I still think it would be better to keep the loadable PCI host drivers
>>>> separate from the ACPI PCI infrastructure. There are a number of
>>>> simplifications that we want to do to the DT based drivers in the long
>>>> run, so it's better if that code is not shared at this level. Abstracting
>>>> out the ECAM code is fine, but at that point you should be able to just
>>>> call it from the ACPI layer.
>>>
>>> The issue is not with this patch (in my opinion). This patch is just
>>> re-arranging how thunder specific data is maintained. Earlier it was
>>> a container_of gen_pci, now it is ->priv of pci_config_window.
>>>
>>> I can see the issue in patches 12 and 13 of this patchset which adds
>>> ACPI fixups into the thunder OF driver.
>>
>> Right, I commented on this one, because it seems to rearrange the code
>> in order to do the later one.
>
> Patches 11- 13 are not from me, and I am not completely on board
> on the approach of adding the sections.We can look at reworking this.
>
>>> The simple approach when doing modular PCI drivers would be to make
>>> pci-thunder-*.c like pci-host-common.c, to be compiled in if configured.
>>> The fie will contain all the Thunder quirks and can export
>>> pci_thunder_ecam_ops.
>>
>> I would argue that we should not export anything from drivers/pci/host,
>> those should really be standalone drivers that do not interact with other
>> subsystems.
>
> pci-host-common.c goes against being standalone. The files calling
> pci_host_common_probe() are expected to have custom ECAM ops
> the way it is written now. We need to have a reasonable way to share
> those ECAM ops if needed by ACPI.
>
>> How much code would you need to duplicate from thunder-ecam to have
>> the same functionality available in ACPI? My expectation is that it's
>> not really that much more compared to the code you need for sharing
>> a single implementation, but you get a lower complexity here, which
>> makes it easier to understand and to rework.
>
> Like I wrote above, the sharing is really simple because both generic
> ACPI and pci-host-common.c have been written for "ECAM with quirks".
>
> The whole pci-thunder-*.c is to support thunder PCI quirks since the
> generic OF is handled by pci-host-common.c and generic ECAM is now
> separated -  duplicating the whole file for ACPI will be bad.

Yes, it would be too much code duplication. Also, we already know 
drivers which need quirks.

We really need to agree on best approach here. Here are requirements 
which came up (please correct me if misunderstood sth):

Arnd:
1. Initial DT driver should be standalone [Arnd]
2. No exported symbols [Arnd]
3. Duplicate necessary code to ACPI framework.

JC:
1. Adding linker section is wrong.
2. Quirks should be exported (pci_thunder_ecam_ops), then no need for 
adding linker section
3. To much duplication to copy code into the ACPI framework.

My opinion:
1. I like linker section because it is easy to maintain and no need to 
export symbols.
2. We need more sophisticated algorithm for matching quirks (DMI is not 
enough and not only for ThunderX drivers). Of course I am open to any 
new suggestions.
3. To much duplication to copy code into the ACPI framework.

Thanks in advance for any pointers.

Thanks,
Tomasz

Thread

[PATCH V6 00/13] Support for generic ACPI based PCI host controller Tomasz Nowicki <tn@semihalf.com> - 2016-04-15 19:10 +0200
  [PATCH V6 11/13] pci, acpi: Match PCI config space accessors against platfrom specific quirks. Tomasz Nowicki <tn@semihalf.com> - 2016-04-15 19:10 +0200
    Re: [PATCH V6 11/13] pci, acpi: Match PCI config space accessors  against platfrom specific quirks. "liudongdong (C)" <liudongdong3@huawei.com> - 2016-04-18 14:00 +0200
      Re: [PATCH V6 11/13] pci, acpi: Match PCI config space accessors  against platfrom specific quirks. Tomasz Nowicki <tn@semihalf.com> - 2016-04-18 14:30 +0200
  [PATCH V6 13/13] pci, pci-thunder-pem: Add ACPI support for ThunderX PEM. Tomasz Nowicki <tn@semihalf.com> - 2016-04-15 19:10 +0200
  [PATCH V6 02/13] pci, acpi: Provide generic way to assign bus domain number. Tomasz Nowicki <tn@semihalf.com> - 2016-04-15 19:10 +0200
    Re: [PATCH V6 02/13] pci, acpi: Provide generic way to assign bus  domain number. Bjorn Helgaas <helgaas@kernel.org> - 2016-04-27 04:30 +0200
      Re: [PATCH V6 02/13] pci, acpi: Provide generic way to assign bus  domain number. Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> - 2016-04-27 13:20 +0200
        Re: [PATCH V6 02/13] pci, acpi: Provide generic way to assign bus  domain number. Bjorn Helgaas <helgaas@kernel.org> - 2016-04-27 18:50 +0200
          Re: [PATCH V6 02/13] pci, acpi: Provide generic way to assign bus  domain number. Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> - 2016-04-27 19:40 +0200
            Re: [PATCH V6 02/13] pci, acpi: Provide generic way to assign bus  domain number. Liviu.Dudau@arm.com - 2016-04-28 10:20 +0200
      Re: [PATCH V6 02/13] pci, acpi: Provide generic way to assign bus  domain number. Tomasz Nowicki <tn@semihalf.com> - 2016-04-27 14:10 +0200
  [PATCH V6 12/13] pci, pci-thunder-ecam: Add ACPI support for ThunderX ECAM. Tomasz Nowicki <tn@semihalf.com> - 2016-04-15 19:10 +0200
    Re: [PATCH V6 12/13] pci, pci-thunder-ecam: Add ACPI support for  ThunderX ECAM. Tomasz Nowicki <tn@semihalf.com> - 2016-04-19 12:30 +0200
      Re: [Linaro-acpi] [PATCH V6 12/13] pci, pci-thunder-ecam: Add ACPI  support for ThunderX ECAM. G Gregory <graeme.gregory@linaro.org> - 2016-04-19 12:50 +0200
        Re: [Linaro-acpi] [PATCH V6 12/13] pci, pci-thunder-ecam: Add ACPI  support for ThunderX ECAM. Graeme Gregory <gg@slimlogic.co.uk> - 2016-04-19 13:20 +0200
          Re: [Linaro-acpi] [PATCH V6 12/13] pci, pci-thunder-ecam: Add ACPI  support for ThunderX ECAM. Tomasz Nowicki <tn@semihalf.com> - 2016-04-19 13:30 +0200
            Re: [Linaro-acpi] [PATCH V6 12/13] pci, pci-thunder-ecam: Add ACPI  support for ThunderX ECAM. G Gregory <graeme.gregory@linaro.org> - 2016-04-19 14:30 +0200
  [PATCH V6 08/13] PCI: generic, thunder: update to use generic ECAM API Tomasz Nowicki <tn@semihalf.com> - 2016-04-15 19:10 +0200
    Re: [PATCH V6 08/13] PCI: generic, thunder: update to use generic ECAM API Arnd Bergmann <arnd@arndb.de> - 2016-04-15 20:50 +0200
      Re: [PATCH V6 08/13] PCI: generic, thunder: update to use generic  ECAM API Jayachandran C <jchandra@broadcom.com> - 2016-04-16 09:30 +0200
        Re: [PATCH V6 08/13] PCI: generic, thunder: update to use generic ECAM API Arnd Bergmann <arnd@arndb.de> - 2016-04-16 09:40 +0200
          Re: [PATCH V6 08/13] PCI: generic, thunder: update to use generic  ECAM API Jayachandran C <jchandra@broadcom.com> - 2016-04-16 16:40 +0200
            Re: [PATCH V6 08/13] PCI: generic, thunder: update to use generic  ECAM API Tomasz Nowicki <tn@semihalf.com> - 2016-04-18 15:10 +0200
              Re: [PATCH V6 08/13] PCI: generic, thunder: update to use generic ECAM API Arnd Bergmann <arnd@arndb.de> - 2016-04-18 16:50 +0200
                Re: [PATCH V6 08/13] PCI: generic, thunder: update to use generic  ECAM API Tomasz Nowicki <tn@semihalf.com> - 2016-04-18 21:40 +0200
                Re: [PATCH V6 08/13] PCI: generic, thunder: update to use generic ECAM API Arnd Bergmann <arnd@arndb.de> - 2016-04-19 15:10 +0200
                Re: [PATCH V6 08/13] PCI: generic, thunder: update to use generic  ECAM API Tomasz Nowicki <tn@semihalf.com> - 2016-04-21 11:30 +0200
                Re: [PATCH V6 08/13] PCI: generic, thunder: update to use generic ECAM API Arnd Bergmann <arnd@arndb.de> - 2016-04-21 11:40 +0200
                Re: [PATCH V6 08/13] PCI: generic, thunder: update to use generic  ECAM API Tomasz Nowicki <tn@semihalf.com> - 2016-04-21 12:10 +0200
                Re: [PATCH V6 08/13] PCI: generic, thunder: update to use generic  ECAM API Jon Masters <jcm@redhat.com> - 2016-04-22 16:40 +0200
                Re: [PATCH V6 08/13] PCI: generic, thunder: update to use generic  ECAM API David Daney <ddaney.cavm@gmail.com> - 2016-04-22 18:10 +0200
    Re: [PATCH V6 08/13] PCI: generic, thunder: update to use generic ECAM API Arnd Bergmann <arnd@arndb.de> - 2016-04-19 23:50 +0200
      Re: [PATCH V6 08/13] PCI: generic, thunder: update to use generic  ECAM API Jayachandran C <jchandra@broadcom.com> - 2016-04-20 02:30 +0200
  [PATCH V6 04/13] pci, of: Move the PCI I/O space management to PCI core code. Tomasz Nowicki <tn@semihalf.com> - 2016-04-15 19:10 +0200
  [PATCH V6 09/13] pci, acpi: Support for ACPI based generic PCI host controller Tomasz Nowicki <tn@semihalf.com> - 2016-04-15 19:10 +0200
    Re: [PATCH V6 09/13] pci, acpi: Support for ACPI based generic PCI  host controller Jayachandran C <jchandra@broadcom.com> - 2016-04-20 21:20 +0200
      Re: [PATCH V6 09/13] pci, acpi: Support for ACPI based generic PCI  host controller Tomasz Nowicki <tn@semihalf.com> - 2016-04-21 11:10 +0200
        Re: [PATCH V6 09/13] pci, acpi: Support for ACPI based generic PCI  host controller Jayachandran C <jchandra@broadcom.com> - 2016-04-22 15:00 +0200
        Re: [PATCH V6 09/13] pci, acpi: Support for ACPI based generic PCI  host controller Jon Masters <jcm@redhat.com> - 2016-04-22 16:50 +0200
          Re: [PATCH V6 09/13] pci, acpi: Support for ACPI based generic PCI  host controller Jon Masters <jcm@redhat.com> - 2016-04-23 17:30 +0200
  [PATCH V6 10/13] arm64, pci, acpi: Start using ACPI based PCI host controller driver for ARM64. Tomasz Nowicki <tn@semihalf.com> - 2016-04-15 19:10 +0200
  [PATCH V6 06/13] arm64, pci, acpi: ACPI support for legacy IRQs parsing and consolidation with DT code. Tomasz Nowicki <tn@semihalf.com> - 2016-04-15 19:20 +0200
    Re: [PATCH V6 06/13] arm64, pci, acpi: ACPI support for legacy IRQs  parsing and consolidation with DT code. Bjorn Helgaas <helgaas@kernel.org> - 2016-04-27 04:50 +0200
      Re: [PATCH V6 06/13] arm64, pci, acpi: ACPI support for legacy IRQs  parsing and consolidation with DT code. Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> - 2016-04-27 13:50 +0200
  [PATCH V6 07/13] PCI: Provide common functions for ECAM mapping Tomasz Nowicki <tn@semihalf.com> - 2016-04-15 19:20 +0200
    Re: [PATCH V6 07/13] PCI: Provide common functions for ECAM mapping Arnd Bergmann <arnd@arndb.de> - 2016-04-15 20:50 +0200
  [PATCH V6 01/13] pci, acpi, x86, ia64: Move ACPI host bridge device companion assignment to core code. Tomasz Nowicki <tn@semihalf.com> - 2016-04-15 19:20 +0200
    Re: [PATCH V6 01/13] pci, acpi, x86, ia64: Move ACPI host bridge  device companion assignment to core code. Bjorn Helgaas <helgaas@kernel.org> - 2016-04-27 00:40 +0200
      Re: [PATCH V6 01/13] pci, acpi, x86, ia64: Move ACPI host bridge  device companion assignment to core code. Tomasz Nowicki <tn@semihalf.com> - 2016-04-27 12:20 +0200
    Re: [PATCH V6 01/13] pci, acpi, x86, ia64: Move ACPI host bridge  device companion assignment to core code. Bjorn Helgaas <helgaas@kernel.org> - 2016-04-27 04:50 +0200
  [PATCH V6 03/13] x86, ia64: Include acpi_pci_{add|remove}_bus to the default pcibios_{add|remove}_bus implementation. Tomasz Nowicki <tn@semihalf.com> - 2016-04-15 19:20 +0200
    Re: [PATCH V6 03/13] x86, ia64: Include acpi_pci_{add|remove}_bus to  the default pcibios_{add|remove}_bus implementation. Bjorn Helgaas <helgaas@kernel.org> - 2016-04-27 04:40 +0200
      Re: [PATCH V6 03/13] x86, ia64: Include acpi_pci_{add|remove}_bus to  the default pcibios_{add|remove}_bus implementation. Tomasz Nowicki <tn@semihalf.com> - 2016-04-27 15:30 +0200
  [PATCH V6 05/13] acpi, pci: Support IO resources when parsing PCI host bridge resources. Tomasz Nowicki <tn@semihalf.com> - 2016-04-15 19:20 +0200
    Re: [PATCH V6 05/13] acpi, pci: Support IO resources when parsing  PCI host bridge resources. Bjorn Helgaas <helgaas@kernel.org> - 2016-04-27 04:40 +0200
      Re: [PATCH V6 05/13] acpi, pci: Support IO resources when parsing PCI  host bridge resources. Jon Masters <jcm@redhat.com> - 2016-04-27 07:40 +0200
      Re: [PATCH V6 05/13] acpi, pci: Support IO resources when parsing  PCI host bridge resources. Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> - 2016-04-27 16:30 +0200
        Re: [PATCH V6 05/13] acpi, pci: Support IO resources when parsing  PCI host bridge resources. Liviu.Dudau@arm.com - 2016-04-27 17:20 +0200
          Re: [PATCH V6 05/13] acpi, pci: Support IO resources when parsing  PCI host bridge resources. Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> - 2016-04-27 18:10 +0200
  Re: [PATCH V6 00/13] Support for generic ACPI based PCI host  controller Jon Masters <jcm@redhat.com> - 2016-04-15 20:20 +0200
    Re: [PATCH V6 00/13] Support for generic ACPI based PCI host controller Jayachandran C <jchandra@broadcom.com> - 2016-04-16 17:40 +0200
      Re: [PATCH V6 00/13] Support for generic ACPI based PCI host  controller Tomasz Nowicki <tn@semihalf.com> - 2016-04-18 15:40 +0200
        Re: [PATCH V6 00/13] Support for generic ACPI based PCI host controller Arnd Bergmann <arnd@arndb.de> - 2016-04-18 16:40 +0200
          Re: [PATCH V6 00/13] Support for generic ACPI based PCI host  controller Tomasz Nowicki <tn@semihalf.com> - 2016-04-18 17:30 +0200
    Re: [PATCH V6 00/13] Support for generic ACPI based PCI host controller Martinez Kristofer <kristofer.s.martinez@gmail.com> - 2016-04-17 11:30 +0200
  Re: [PATCH V6 00/13] Support for generic ACPI based PCI host controller Duc Dang <dhdang@apm.com> - 2016-04-16 20:40 +0200
  Re: [PATCH V6 00/13] Support for generic ACPI based PCI host  controller Sinan Kaya <okaya@codeaurora.org> - 2016-04-17 06:20 +0200
  Re: [PATCH V6 00/13] Support for generic ACPI based PCI host  controller Jeremy Linton <jeremy.linton@arm.com> - 2016-04-25 19:30 +0200

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