[PATCH][V4] powerpc/fsl-pci: Add pci inbound/outbound PM support

[Jia Hongtao-B38951]

> -----Original Message-----
> From: Kumar Gala [mailto:galak at kernel.crashing.org]
> Sent: Wednesday, September 19, 2012 11:49 PM
> To: Jia Hongtao-B38951
> Cc: linuxppc-dev at lists.ozlabs.org; Li Yang-R58472; Wood Scott-B07421
> Subject: Re: [PATCH][V4] powerpc/fsl-pci: Add pci inbound/outbound PM
> support
> 
> >>> On Sep 17, 2012, at 9:10 PM, Jia Hongtao wrote:
> >>>
> >>>> Power supply for PCI inbound/outbound window registers is off when
> >>>> system go to deep-sleep state. We save the values of registers
> before
> >>>> suspend and restore to registers after resume.
> >>>>
> >>>> Signed-off-by: Jiang Yutang <b14898 at freescale.com>
> >>>> Signed-off-by: Jia Hongtao <B38951 at freescale.com>
> >>>> Signed-off-by: Li Yang <leoli at freescale.com>
> >>>> ---
> >>>> Changes for V4:
> >>>> We just rebase the patch upon following patch:
> >>>> powerpc/fsl-pci: Unify pci/pcie initialization code
> >>>>
> >>>> arch/powerpc/include/asm/pci-bridge.h |    2 +-
> >>>> arch/powerpc/sysdev/fsl_pci.c         |  121
> >>> +++++++++++++++++++++++++++++++++
> >>>> 2 files changed, 122 insertions(+), 1 deletions(-)
> >>>
> >>> Did you ever compare this to just re-parsing device tree method?
> >>>
> >>> - k
> >>
> >> I tested the re-parsing way by using setup_pci_atmu() when resume.
> >> And I found out that re-parsing will *change* outbound IO translation
> >> address regitster.
> >>
> >> It seems that in the first bootup, after setup_atmu()
> >> pcibios_setup_phb_resources() may update hose->io_resource, but atmu
> >> is not updated according to the new hose->io_resource value.
> >> In resume from sleep setup_atmu() will reset atmu according to the
> >> new hose->io_resource value. So the setup_atmu() will cause different
> >> result on outbound IO register between first bootup and resume from
> >> sleep.
> >>
> >> So... There's a possibility that in the first bootup atmu is not setup
> >> properly.
> >
> > [Are you seeing this happen in your testing?  If so its a bug we need
> to look at fixing.]
> >
> > Yes, I see this in my testing.
> > Also PCIe ethernet card works well after resuming from sleep in both
> save/restore
> > and re-parsing way. (Maybe PCIe ethernet card don't need outbound IO
> resource)
> > So, I guess the result of re-parsing (actually it's re-setup) is right
> and ATMU is not setup
> > properly at the first bootup.
> 
> Are you seeing the following message - "PCI: I/O resource not set for
> host bridge" ?

No.

> 
> Trying to understand why you'd hit the reassignment of io_resource.
> 
> - k
> 

I did some investigations and the conclusion is:

io_resource.flags & IORESOURCE_IO are both positive but io_resource.start
is 0 before pcibios_setup_phb_io_space() is done.

The sequence of related process listed below:
fsl_add_bridge() -> setup_pci_atmu()
pcibios_init() -> pcibios_scan_phb() -> pcibios_setup_phb_io_space()

Because fsl_add_bridge() must be finished before pcibios_init() so ATMU
is set when io_resource.start is 0. That means outbound IO regs are not
set.

If system re-setup ATMU the io_resource.start has already updated so
outbound IO regs are set.

My question is:
Is there any problem if outbound IO regs are not set in first bootup?

- Hongtao.