On Fri, Jan 02, 2015 at 09:09:33PM +0000, Arnd Bergmann wrote:

On Friday 02 January 2015 12:18:06 Suravee Suthikulanit wrote:

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On 1/2/2015 5:55 AM, Lorenzo Pieralisi wrote:

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Hi Suravee,

On Mon, Dec 29, 2014 at 07:32:44PM +0000, Suravee Suthikulpanit wrote:

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Hi,

I am not sure if this thread is still alive. I'm trying to see what I
can do to help clean up/convert to make the PCI GHC also works for arm64
w/ zero or minimal ifdefs.

Please let me know if someone is already working on this. I noticed that
Lorenzo's patches has already been in 3.19-rc1, and in Bjorn's
pci/domain branch. Otherwise, I'll try to continue the work based on the
sample patch from Arnd here.

If I am not mistaken, the only bit missing to remove pci_sys_data (and so
having a generic host controller driver that works on ARM32/64) is generic
MSI management.

Lorenzo,

Do you mean to remove pci_sys_data from pci-host-generic.c or removing 
it completely? I assume the former case.

Something inbetween: We should be able to remove pci_sys_data and
pci_common_init_dev from all drivers in drivers/pci/host/, but keep them
for all drivers in arch/arm/*/pci.c

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So, looking at the current code in the pci-host-generic.c, my 
understanding is that the:
     *gen_pci = pci_bus->sysdata->private_data
will be changed to:
     *gen_pci = pci_bus->sysdata

Then, we can simply just call pci_scan_root_bus() directly since we no 
longer need to declare hw_pci for calling pci_common_init_dev().

Right.

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I know for certain Marc is working on it, and the solution is WIP,
I think we should prevent adding more churn to pci_sys_data, since
I managed to remove most of the dependencies (domain, mem_offset).

Thanks for cleaning up the domain and mem_offset.

I saw Marc's irq/msi_domain patch series 
(http://git.kernel.org/cgit/linux/kernel/git/maz/arm-platforms.git/log/?h=irq/msi_domain). 


My understanding is that deals with associating the newly introduced 
msi_domain to each device, which replaces the need for pci_bus->msi and 
hw_pci->msi_ctrl when configure with CONFIG_PCI_MSI_IRQ_DOMAIN (not sure 
if this would be the plan for all arm32).  For ARM32, if not define 
CONFIG_PCI_MSI_IRQ_DOMAIN, it would still fall back to using the 
[pci_sys_data|hw_pci]->msi_ctrl.

For all I can tell, we have two cases on ARM regarding MSI:

- arch/arm/mach-iop13xx/pci.c uses its own
  arch_setup_msi_irq/arch_teardown_msi_irq implementation and does not
  use pci_bus->msi.

- everything else that supports MSI has a modern driver with multiplatform
  support and uses msi_controller. If any platform wants to support GICv2m,
  we have to use CONFIG_PCI_MSI_IRQ_DOMAIN for all of them, and that
  seems like the best way forward.

Yes, I think that's the current situation. With a hook (added by Marc's
code) in PCI core to set the msi domain (DT), all we need to do is convert
the generic host controller code to pci_scan_root_bus() and remove the
pcibios init calls, it is a mechanical change when all patches mentioned
above are merged.

Thanks,
Lorenzo