From: "Rafael J. Wysocki" <rjw@sisk.pl>
To: huang ying <huang.ying.caritas@gmail.com>
Cc: Huang Ying <ying.huang@intel.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: Mon, 7 May 2012 23:00:46 +0200 [thread overview]
Message-ID: <201205072300.46939.rjw@sisk.pl> (raw)
In-Reply-To: <CAC=cRTMoSCoWYvVqhBb5_SD=+bJuQ86-eifDqZxtGYRW_Ok9eg@mail.gmail.com>
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?
> >> + */
> >> + if (bridge && bridge->current_state != PCI_D0)
> >> + return 0;
> >> +
> >> if (pme_poll_reset && dev->pme_poll)
> >> dev->pme_poll = false;
> >>
> >> --- a/drivers/pci/pcie/portdrv_pci.c
> >> +++ b/drivers/pci/pcie/portdrv_pci.c
> >> @@ -11,6 +11,7 @@
> >> #include <linux/kernel.h>
> >> #include <linux/errno.h>
> >> #include <linux/pm.h>
> >> +#include <linux/pm_runtime.h>
> >> #include <linux/init.h>
> >> #include <linux/pcieport_if.h>
> >> #include <linux/aer.h>
> >> @@ -99,6 +100,27 @@ static int pcie_port_resume_noirq(struct
> >> return 0;
> >> }
> >>
> >> +#ifdef CONFIG_PM_RUNTIME
> >> +static int pcie_port_runtime_suspend(struct device *dev)
> >> +{
> >> + struct pci_dev *pdev = to_pci_dev(dev);
> >> +
> >
> > A comment explaining why this is needed here would be welcome.
>
> Sorry, do not catch your idea exactly. What is needed? Why do we
> need to add PCIe port runtime suspend support?
No, why we need to call pci_save_state() from here and pci_restore_state()
from the corresponding resume routine.
In theory that shouldn't be necessary, because the PCI bus type's
runtime suspend/resume routines do the save/restore of the PCI config space.
Thanks,
Rafael
next prev parent reply other threads:[~2012-05-07 20:56 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 [this message]
2012-05-11 7:57 ` Huang Ying
2012-05-11 18:44 ` Rafael J. Wysocki
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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