From: ebiederm@xmission.com (Eric W. Biederman)
To: Bjorn Helgaas <bhelgaas@google.com>
Cc: Huang Ying <ying.huang@intel.com>,
linux-pm@vger.kernel.org, linux-pci@vger.kernel.org,
kexec@lists.infradead.org, linux-kernel@vger.kernel.org,
"Rafael J. Wysocki" <rjw@sisk.pl>
Subject: Re: [RFC 1/3] PCI/PM: Fix kexec for D3cold and bridge suspending
Date: Thu, 20 Sep 2012 00:38:33 -0700 [thread overview]
Message-ID: <877grpywhy.fsf@xmission.com> (raw)
In-Reply-To: <CAErSpo5fVbN2vD5Omc7dGJFWUccYZoCOVRF4YmXPe2Oxm81u5g@mail.gmail.com> (Bjorn Helgaas's message of "Mon, 17 Sep 2012 14:54:16 -0600")
Bjorn Helgaas <bhelgaas@google.com> writes:
> +cc Eric and kexec list
>
> On Mon, Sep 17, 2012 at 2:54 AM, Huang Ying <ying.huang@intel.com> wrote:
>> If PCI devices are put into D3cold before kexec, because the
>> configuration registers of PCI devices in D3cold are not accessible.
>>
>> And if PCI bridges are put into low power state before kexec,
>> configuration registers of PCI devices underneath the PCI bridges are
>> not accessible too.
>>
>> These will make some PCI devices can not be scanned after kexec, so
>> resume the PCI devices in D3cold or PCI bridges in low power state
>> before kexec.
>
> Don't we need to resume the device even without the kexec issue? And
> even if it's in D1 or D2?
The basic requirement is that the device needs to be visible so we can
auto discover it. As I recall most sleep states don't make the device
invisible and we can handle the rest in the device initializatoin code.
> It looks to me like pci_msi_shutdown() (and probably drv->shutdown())
> depend on the device being in D0.
There is certainly a depenency on the config registers being visible.
Although I don't know if much will go wrong if they aren't.
Ceratinly pci_msi_shutdown doesn't have anything to do if the device has
had so much power removed that the device is not even exectuing.
Eric
>> Signed-off-by: Huang Ying <ying.huang@intel.com>
>> ---
>> drivers/pci/pci-driver.c | 4 ++++
>> 1 file changed, 4 insertions(+)
>>
>> --- a/drivers/pci/pci-driver.c
>> +++ b/drivers/pci/pci-driver.c
>> @@ -421,6 +421,10 @@ static void pci_device_shutdown(struct d
>> struct pci_dev *pci_dev = to_pci_dev(dev);
>> struct pci_driver *drv = pci_dev->driver;
>>
>> + /* Resume bridges and devices in D3cold for kexec to work properly */
>> + if (pci_dev->current_state == PCI_D3cold || pci_dev->subordinate)
>> + pm_runtime_resume(dev);
>> +
>> if (drv && drv->shutdown)
>> drv->shutdown(pci_dev);
>> pci_msi_shutdown(pci_dev);
>
> _______________________________________________
> kexec mailing list
> kexec@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/kexec
next prev parent reply other threads:[~2012-09-20 7:38 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-17 8:54 [RFC 0/3] PCI/PM: RTD3 fixes/changes for 3.7 Huang Ying
2012-09-17 8:54 ` [RFC 1/3] PCI/PM: Fix kexec for D3cold and bridge suspending Huang Ying
2012-09-17 20:54 ` Bjorn Helgaas
2012-09-20 7:38 ` Eric W. Biederman [this message]
2012-09-20 8:19 ` Huang Ying
2012-09-20 8:27 ` Eric W. Biederman
2012-09-20 19:20 ` Rafael J. Wysocki
2012-09-21 0:28 ` Huang Ying
2012-09-21 19:30 ` Rafael J. Wysocki
2012-09-17 8:54 ` [RFC 2/3] PCI/PM: Make PCI devices notified when its power resource turned on Huang Ying
2012-09-20 19:33 ` Rafael J. Wysocki
2012-09-17 8:54 ` [RFC 3/3] PCI/PM: Disable PME poll for PCIe devices Huang Ying
2012-09-20 19:31 ` Rafael J. Wysocki
2012-09-20 19:39 ` Matthew Garrett
2012-09-21 1:50 ` Huang Ying
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