[PATCH 5/6] powerpc/fsl-pci: Add pci inbound/outbound PM support

[Jia Hongtao-B38951]

> -----Original Message-----
> From: Linuxppc-dev [mailto:linuxppc-dev-
> bounces+b38951=freescale.com at lists.ozlabs.org] On Behalf Of Kumar Gala
> Sent: Wednesday, August 08, 2012 8:47 PM
> To: Jia Hongtao-B38951
> Cc: Wood Scott-B07421; linuxppc-dev at lists.ozlabs.org; Li Yang-R58472
> Subject: Re: [PATCH 5/6] powerpc/fsl-pci: Add pci inbound/outbound PM
> support
> 
> >>>>>>
> >>>>>> On Jul 24, 2012, at 5:20 AM, 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>
> >>>>>>> ---
> >>>>>>> arch/powerpc/include/asm/pci-bridge.h |    2 +-
> >>>>>>> arch/powerpc/sysdev/fsl_pci.c         |  121
> >>>>>> +++++++++++++++++++++++++++++++++
> >>>>>>> 2 files changed, 122 insertions(+), 1 deletions(-)
> >>>>>>
> >>>>>> Remind me why we need to save/restore PCI ATMUs, why not just
> >>>>>> re-parse the device tree to restore?
> >>>>>>
> >>>>>> - k
> >>>>>
> >>>>> Save/restore is the more efficient way. Latency of sleep/wakeup is
> >>>>> one of most important features in power management.
> >>>>>
> >>>>> -Hongtao.
> >>>>
> >>>> I don't think the time it takes to run through setup_pci_atmu() is
> >>>> that long compared to fsl_pci_resume().
> >>>>
> >>>> Also, don't you need to setup PCICCSRBAR and do setup_pci_cmd() on
> >> resume?
> >>>>
> >>>> - k
> >>>
> >>> Hi Kumar,
> >>> I did some tests on P1022DS and found out that PCI_CMD and PCICSRBAR
> >>> is not lost when system in deep sleep. We don't need to save it.
> >>
> >> How does the PCI code know you're entering deep sleep and not
> hibernation?
> >>
> >> -Scott
> >
> > When system come back from hibernation PCI will be initialized again.
> > So no need to save PCI_CMD and PEXCSRBAR.
> >
> > -Hongtao.
> >
> 
> What do you mean PCI will be initialized again?  What code path are you
> talking about that would set PCI_CMD & PEXCSRBAR?
> 
> - k


In hibernation mode:

When system come back from hibernation kernel will start up again.
Before loading hibernation image PCI initialization has already done.
Some other hardware also re-init again.

-Hongtao.