[PATCH] powerpc/85xx: Save and restore pcie ATMU windows for PM

[Kushwaha Prabhakar-B32579]

> -----Original Message-----
> From: Kumar Gala [mailto:galak at kernel.crashing.org]
> Sent: Friday, May 20, 2011 10:19 AM
> To: Kushwaha Prabhakar-B32579
> Cc: linuxppc-dev at lists.ozlabs.org; meet2prabhu at gmail.com; Jiang Yutang-
> B14898
> Subject: Re: [PATCH] powerpc/85xx: Save and restore pcie ATMU windows for
> PM
> 
> 
> On May 19, 2011, at 11:41 PM, Kushwaha Prabhakar-B32579 wrote:
> 
> >
> >
> >> -----Original Message-----
> >> From: Kumar Gala [mailto:galak at kernel.crashing.org]
> >> Sent: Thursday, May 19, 2011 6:53 PM
> >> To: Kushwaha Prabhakar-B32579
> >> Cc: linuxppc-dev at lists.ozlabs.org; meet2prabhu at gmail.com; Jiang
> >> Yutang-
> >> B14898
> >> Subject: Re: [PATCH] powerpc/85xx: Save and restore pcie ATMU windows
> >> for PM
> >>
> >>
> >> On May 19, 2011, at 6:22 AM, Kushwaha Prabhakar-B32579 wrote:
> >>
> >>> Hi Kumar,
> >>> Please find my answer in-lined
> >>>
> >>>> -----Original Message-----
> >>>> From: Kumar Gala [mailto:galak at kernel.crashing.org]
> >>>> Sent: Thursday, May 19, 2011 12:00 PM
> >>>> To: Kushwaha Prabhakar-B32579
> >>>> Cc: linuxppc-dev at lists.ozlabs.org; meet2prabhu at gmail.com; Jiang
> >>>> Yutang-
> >>>> B14898
> >>>> Subject: Re: [PATCH] powerpc/85xx: Save and restore pcie ATMU
> >>>> windows for PM
> >>>>
> >>>>
> >>>> On Apr 28, 2011, at 1:38 AM, Prabhakar Kushwaha wrote:
> >>>>
> >>>>> D3-cold state indicates removal of the clock and power. however
> >>>>> auxiliary (AUX) Power may remain available even after the main
> >>>>> power
> >>>> rails are powered down.
> >>>>>
> >>>>> wakeup from D3-cold state requires full context restore. Other
> >>>>> things are taken care in pci-driver except ATMUs.
> >>>>> ATMU windows needs to be saved and restored during suspend and
> >> resume.
> >>>>>
> >>>>> Signed-off-by: Jiang Yutang <b14898 at freescale.com>
> >>>>> Signed-off-by: Prabhakar Kushwaha <prabhakar at freescale.com>
> >>>>> ---
> >>>>> Based upon
> >>>>> git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.g
> >>>>> it
> >>>>> (b
> >>>>> ranch master)
> >>>>>
> >>>>> arch/powerpc/sysdev/fsl_pci.c |  116
> >>>> +++++++++++++++++++++++++++++++++++++++++
> >>>>> arch/powerpc/sysdev/fsl_pci.h |    7 ++-
> >>>>> 2 files changed, 121 insertions(+), 2 deletions(-)
> >>>>
> >>>> Is this patch for when we are a host or agent?
> >>>
> >>> This patch is independent of host or agent. It is for supporting D3
> >> cold state for P1022.
> >>> These functions are called during System level suspend and resume.
> >>>
> >>> --Prabhakar
> >>
> >> I'm trying to figure out why this is limited to P1022.
> >
> > Till now, No SOC was supporting D3 cold state. First time P1022
> supporting it.
> > Note:  D3 cold state == PCIe block Power down
> >
> 
> I'm wondering a few things:
> 
> 1. Is there any reason not to do this for ALL FSL PCIe SoCs?

Yes, I am agree with you. It can be done. 
But as only P1022 SOC supporting it. There is no use of handling it. 

> 2. why do bother saving state, we don't we re-parse the .dts and
> reconfigure ATMUs that way?

I also thought of this case. But Agent use case scenario forbid me to do this. 
As ATMU's are programmed by host depending upon different use case . And this information is never stored in the dts.

--Prabhakar