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

[Kumar Gala]

On Aug 7, 2012, at 10:34 AM, Scott Wood wrote:

> On 08/07/2012 05:11 AM, Jia Hongtao-B38951 wrote:
>> 
>> 
>>> -----Original Message-----
>>> From: Kumar Gala [mailto:galak at kernel.crashing.org]
>>> Sent: Tuesday, July 31, 2012 9:37 PM
>>> To: Jia Hongtao-B38951
>>> Cc: linuxppc-dev at lists.ozlabs.org; Wood Scott-B07421; Li Yang-R58472
>>> Subject: Re: [PATCH 5/6] powerpc/fsl-pci: Add pci inbound/outbound PM
>>> support
>>> 
>>> 
>>> On Jul 30, 2012, at 1:09 AM, Jia Hongtao-B38951 wrote:
>>> 
>>>>> -----Original Message-----
>>>>> From: Kumar Gala [mailto:galak at kernel.crashing.org]
>>>>> Sent: Friday, July 27, 2012 9:24 PM
>>>>> To: Jia Hongtao-B38951
>>>>> Cc: linuxppc-dev at lists.ozlabs.org; Wood Scott-B07421; 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
> 

Also, are you sure PCICSRBAR does not need restoring?  I'd be surprised if PCICSRBAR was ok, but the ATMUs where not.

- k