linux-kernel - Re: [PATCH -v4 2/2] PCIe: Add PCIe runtime D3cold support

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Date:	Wed, 30 May 2012 23:49:30 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Huang Ying <ying.huang@...el.com>
Cc:	Bjorn Helgaas <bhelgaas@...gle.com>, ming.m.lin@...el.com,
	linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
	Zheng Yan <zheng.z.yan@...el.com>
Subject: Re: [PATCH -v4 2/2] PCIe: Add PCIe runtime D3cold support

On Tuesday, May 22, 2012, Rafael J. Wysocki wrote:
> On Friday, May 18, 2012, Huang Ying wrote:
> > This patch adds runtime D3cold support to PCIe bus.  D3cold is the
> > deepest power saving state for PCIe devices.  Where the main PCIe link
> > will be powered off totally, so before the PCIe main link is powered
> > on again, you can not access the device, even the configuration space,
> > which is still accessible in D3hot.  Because the main PCIe link is not
> > available, the PCI PM registers can not be used to put device into/out
> > of D3cold state, that will be done by platform logic such as ACPI
> > _PR3.
> > 
> > To support remote wake up in D3cold, aux power is supplied, and a
> > side-band pin: WAKE# is used to notify remote wake up event, the pin
> > is usually connected to platform logic such as ACPI GPE.  This is
> > quite different with other power saving states, where remote wake up
> > is notified via PME message through the PCIe main link.
> > 
> > PCIe devices in plug-in slot usually has no direct platform logic, for
> > example, there is usually no ACPI _PR3 for them.  The D3cold support
> > for these devices can be done via the PCIe port connected to it.  When
> > power on/off the PCIe port, the corresponding PCIe devices are powered
> > on/off too.  And the remote wake up event from PCIe device will be
> > notified to the corresponding PCIe port.
> > 
> > The PCI subsystem D3cold support and corresponding ACPI platform
> > support is implemented in the patch.  Including the support for PCIe
> > devices in plug-in slot.
> > 
> > For more information about PCIe D3cold and corresponding ACPI support,
> > please refer to:
> > 
> > - PCI Express Base Specification Revision 2.0
> > - Advanced Configuration and Power Interface Specification Revision 5.0
> > 
> > Originally-by: Zheng Yan <zheng.z.yan@...el.com>
> > Signed-off-by: Huang Ying <ying.huang@...el.com>
> 
> Reviewed-by: Rafael J. Wysocki <rjw@...k.pl>

On a second thought ...

> > ---
> >  drivers/pci/pci-acpi.c         |   23 +++++++-
> >  drivers/pci/pci-driver.c       |    3 +
> >  drivers/pci/pci-sysfs.c        |   29 ++++++++++
> >  drivers/pci/pci.c              |  110 +++++++++++++++++++++++++++++++++++++----
> >  drivers/pci/pci.h              |    1 
> >  drivers/pci/pcie/portdrv_pci.c |   44 ++++++++++++++--
> >  include/linux/pci.h            |   16 ++++-
> >  7 files changed, 205 insertions(+), 21 deletions(-)
> > 
> > --- a/drivers/pci/pci-acpi.c
> > +++ b/drivers/pci/pci-acpi.c
> > @@ -48,6 +48,12 @@ static void pci_acpi_wake_dev(acpi_handl
> >  	if (event != ACPI_NOTIFY_DEVICE_WAKE || !pci_dev)
> >  		return;
> >  
> > +	if (pci_dev->current_state == PCI_D3cold) {
> > +		pci_wakeup_event(pci_dev);
> > +		pm_runtime_resume(&pci_dev->dev);
> > +		return;
> > +	}
> > +
> >  	if (!pci_dev->pm_cap || !pci_dev->pme_support
> >  	     || pci_check_pme_status(pci_dev)) {
> >  		if (pci_dev->pme_poll)
> > @@ -187,10 +193,13 @@ acpi_status pci_acpi_remove_pm_notifier(
> >  
> >  static pci_power_t acpi_pci_choose_state(struct pci_dev *pdev)
> >  {
> > -	int acpi_state;
> > +	int acpi_state, d_max;
> >  
> > -	acpi_state = acpi_pm_device_sleep_state(&pdev->dev, NULL,
> > -						ACPI_STATE_D3);

I wonder what tree this patch is against?  The code above doesn't seem to
be present in the current mainline.

Thanks,
Rafael
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