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

[Scott Wood <scottwood@freescale.com>]

On 08/07/2012 05:11 AM, Jia Hongtao-B38951 wrote:
> 
> 
>> -----Original Message-----
>> From: Kumar Gala [mailto:galak@kernel.crashing.org]
>> Sent: Tuesday, July 31, 2012 9:37 PM
>> To: Jia Hongtao-B38951
>> Cc: linuxppc-dev@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@kernel.crashing.org]
>>>> Sent: Friday, July 27, 2012 9:24 PM
>>>> To: Jia Hongtao-B38951
>>>> Cc: linuxppc-dev@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@freescale.com>
>>>>> Signed-off-by: Jia Hongtao <B38951@freescale.com>
>>>>> Signed-off-by: Li Yang <leoli@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