From: "Rafael J. Wysocki" <rjw@sisk.pl>
To: Huang Ying <ying.huang@intel.com>
Cc: huang ying <huang.ying.caritas@gmail.com>,
Bjorn Helgaas <bhelgaas@google.com>,
ming.m.lin@intel.com, linux-kernel@vger.kernel.org,
linux-pm@vger.kernel.org, Zheng Yan <zheng.z.yan@intel.com>
Subject: Re: [RFC v2 3/5] PCIe, Add runtime PM support to PCIe port
Date: Fri, 11 May 2012 20:44:15 +0200 [thread overview]
Message-ID: <201205112044.15415.rjw@sisk.pl> (raw)
In-Reply-To: <1336723068.6487.8.camel@yhuang-dev>
On Friday, May 11, 2012, Huang Ying wrote:
> On Mon, 2012-05-07 at 23:00 +0200, Rafael J. Wysocki wrote:
> > On Saturday, May 05, 2012, huang ying wrote:
> > > On Sat, May 5, 2012 at 3:43 AM, Rafael J. Wysocki <rjw@sisk.pl> wrote:
> > > > On Friday, May 04, 2012, Huang Ying wrote:
> > > >> From: Zheng Yan <zheng.z.yan@intel.com>
> > > >>
> > > >> This patch adds runtime PM support to PCIe port. This is needed by
> > > >> PCIe D3cold support, where PCIe device in slot may be powered on/off
> > > >> by PCIe port.
> > > >>
> > > >> Because runtime suspend is broken for some chipset, a white list is
> > > >> used to enable runtime PM support for only chipset known to work.
> > > >>
> > > >> Signed-off-by: Zheng Yan <zheng.z.yan@intel.com>
> > > >> Signed-off-by: Huang Ying <ying.huang@intel.com>
> > > >> ---
> > > >> drivers/pci/pci.c | 9 +++++++++
> > > >> drivers/pci/pcie/portdrv_pci.c | 40 ++++++++++++++++++++++++++++++++++++++++
> > > >> 2 files changed, 49 insertions(+)
> > > >>
> > > >> --- a/drivers/pci/pci.c
> > > >> +++ b/drivers/pci/pci.c
> > > >> @@ -1476,6 +1476,15 @@ bool pci_check_pme_status(struct pci_dev
> > > >> */
> > > >> static int pci_pme_wakeup(struct pci_dev *dev, void *pme_poll_reset)
> > > >> {
> > > >> + struct pci_dev *bridge = dev->bus->self;
> > > >> +
> > > >> + /*
> > > >> + * If bridge is in low power state, the configuration space of
> > > >> + * subordinate devices may be not accessible
> > > >
> > > > Please also say in the comment _when_ this is possible. That's far from
> > > > obvious, because the runtime PM framework generally ensures that parents are
> > > > resumed before the children, so the comment should describe the particular
> > > > scenario leading to this situation.
> > >
> > > OK. I will add something like below into comments.
> > >
> > > This is possible when doing PME poll.
> >
> > Well, that doesn't really explain much. :-)
> >
> > I _think_ the situation is when a device causes WAKE# to be generated and
> > the platform receives a GPE as a result and we get an ACPI_NOTIFY_DEVICE_WAKE
> > notification for the device, which may be under a bridge (PCIe port really)
> > in D3_cold. Is that the case?
>
> That is not the case now. Because we do not use pci_pme_wakeup_bus() in
> ACPI handler now.
>
> But for PME poll, if some subordinate devices under a bridge is put in
> low power state, we still need to access configuration space of
> subordinate devices to poll PME status even when bridge is in low power
> state. That may not work.
OK, I see. You mean that pci_pme_list_scan() should avoid checking the
PME status for devices whose parents (bridges) are in low-power states, right?
I think that that check should be made by pci_pme_list_scan() itself, then.
Thanks,
Rafael
next prev parent reply other threads:[~2012-05-11 18:39 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-04 8:13 [RFC v2 0/5] PCIe, Add PCIe runtime D3cold support Huang Ying
2012-05-04 8:13 ` [RFC v2 1/5] PM, Runtime, Add power_must_be_on flag Huang Ying
2012-05-04 19:37 ` Rafael J. Wysocki
2012-05-05 5:15 ` huang ying
2012-05-07 20:33 ` Rafael J. Wysocki
2012-05-04 19:50 ` Bjorn Helgaas
2012-05-05 5:59 ` huang ying
2012-05-07 20:37 ` Rafael J. Wysocki
2012-05-04 8:13 ` [RFC v2 2/5] PM, Add sysfs file power_off to control device power off policy Huang Ying
2012-05-04 19:33 ` Rafael J. Wysocki
2012-05-05 6:29 ` huang ying
2012-05-07 20:53 ` Rafael J. Wysocki
2012-05-08 1:44 ` Huang Ying
2012-05-08 21:34 ` Rafael J. Wysocki
2012-05-09 6:46 ` Huang Ying
2012-05-09 10:38 ` Rafael J. Wysocki
2012-05-10 0:55 ` Huang Ying
2012-05-10 14:48 ` Alan Stern
2012-05-10 19:03 ` Rafael J. Wysocki
2012-05-04 19:50 ` Bjorn Helgaas
2012-05-04 21:00 ` Rafael J. Wysocki
2012-05-05 6:36 ` huang ying
2012-05-04 8:13 ` [RFC v2 3/5] PCIe, Add runtime PM support to PCIe port Huang Ying
2012-05-04 19:43 ` Rafael J. Wysocki
2012-05-05 6:46 ` huang ying
2012-05-07 21:00 ` Rafael J. Wysocki
2012-05-11 7:57 ` Huang Ying
2012-05-11 18:44 ` Rafael J. Wysocki [this message]
2012-05-04 19:50 ` Bjorn Helgaas
2012-05-04 20:55 ` Rafael J. Wysocki
2012-05-05 6:54 ` huang ying
2012-05-07 21:06 ` Rafael J. Wysocki
2012-05-05 6:53 ` huang ying
2012-05-04 8:13 ` [RFC v2 4/5] ACPI, PM, Specify lowest allowed state for device sleep state Huang Ying
2012-05-04 20:10 ` Rafael J. Wysocki
2012-05-05 7:25 ` huang ying
2012-05-07 21:15 ` Rafael J. Wysocki
2012-05-08 1:49 ` Huang Ying
2012-05-04 8:13 ` [RFC v2 5/5] PCIe, Add PCIe runtime D3cold support Huang Ying
2012-05-04 19:51 ` Bjorn Helgaas
2012-05-05 7:34 ` huang ying
2012-05-04 20:50 ` Rafael J. Wysocki
2012-05-05 8:08 ` huang ying
2012-05-07 21:22 ` Rafael J. Wysocki
2012-05-08 2:22 ` Huang Ying
2012-05-08 8:34 ` Huang Ying
2012-05-10 19:28 ` Rafael J. Wysocki
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