-----Original Message-----
From: Kumar Gala [mailto:<redacted>]
Sent: Thursday, August 09, 2012 9:08 PM
To: Li Yang-R58472
Cc: Jia Hongtao-B38951; Wood Scott-B07421; <redacted>;
Li Yang-R58472
Subject: Re: [PATCH 5/6] powerpc/fsl-pci: Add pci inbound/outbound PM
support
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On Aug 9, 2012, at 12:05 AM, Li Yang wrote:
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On Thu, Aug 9, 2012 at 10:52 AM, Jia Hongtao-B38951
[off-list ref] wrote:
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-----Original Message-----
From: Linuxppc-dev [mailto:linuxppc-dev-
bounces+b38951=3Dfreescale.com@lists.ozlabs.org] On Behalf Of Kumar
bounces+Gala
Sent: Wednesday, August 08, 2012 8:47 PM
To: Jia Hongtao-B38951
Cc: Wood Scott-B07421; <redacted>; Li Yang-R58472
Subject: Re: [PATCH 5/6] powerpc/fsl-pci: Add pci inbound/outbound
PM support
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On Jul 24, 2012, at 5:20 AM, Jia Hongtao wrote:
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Power supply for PCI inbound/outbound window registers is off
when
system
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go to deep-sleep state. We save the values of registers
before suspend and restore to registers after resume.
Signed-off-by: Jiang Yutang <redacted>
Signed-off-by: Jia Hongtao <redacted>
Signed-off-by: Li Yang <redacted>
---
arch/powerpc/include/asm/pci-bridge.h | 2 +-
arch/powerpc/sysdev/fsl_pci.c | 121
+++++++++++++++++++++++++++++++++
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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?
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- 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.
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How does the PCI code know you're entering deep sleep and not
hibernation?
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-Scott
When system come back from hibernation PCI will be initialized again=
.
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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.
In current Linux implementation, restoring from hibernation image is
using late initcall. By that time, all the platform devices are
already initialized like a fresh boot.
- Leo
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I ask against, what specific code path (I'd like a call trace) would
cause PCI_CMD and PEXCSRBAR to be set in the wakeup case?
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- k
The code path is the same as a fresh boot:
fsl_add_bridge()
-> setup_pci_cmd() [PCI_CMD is set]
-> setup_pci_atmu() [PEXCSRBAR is set]
- Hongtao.