From 967577b062417b4e4b8e27b711220f4124f5153a Mon Sep 17 00:00:00 2001 From: Huang Ying Date: Tue, 20 Nov 2012 16:08:22 +0800 Subject: PCI/PM: Keep runtime PM enabled for unbound PCI devices For unbound PCI devices, what we need is: - Always in D0 state, because some devices do not work again after being put into D3 by the PCI bus. - In SUSPENDED state if allowed, so that the parent devices can still be put into low power state. To satisfy these requirements, the runtime PM for the unbound PCI devices are disabled and set to SUSPENDED state. One issue of this solution is that the PCI devices will be put into SUSPENDED state even if the SUSPENDED state is forbidden via the sysfs interface (.../power/control) of the device. This is not an issue for most devices, because most PCI devices are not used at all if unbound. But there are exceptions. For example, unbound VGA card can be used for display, but suspending its parents makes it stop working. To fix the issue, we keep the runtime PM enabled when the PCI devices are unbound. But the runtime PM callbacks will do nothing if the PCI devices are unbound. This way, we can put the PCI devices into SUSPENDED state without putting the PCI devices into D3 state. Reference: https://bugzilla.kernel.org/show_bug.cgi?id=48201 Signed-off-by: Huang Ying Signed-off-by: Bjorn Helgaas Acked-by: Alan Stern Acked-by: Rafael J. Wysocki CC: stable@vger.kernel.org # v3.6+ --- drivers/pci/pci.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'drivers/pci/pci.c') diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index aabf64798bd..8e06adb9898 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -1900,6 +1900,8 @@ void pci_pm_init(struct pci_dev *dev) u16 pmc; pm_runtime_forbid(&dev->dev); + pm_runtime_set_active(&dev->dev); + pm_runtime_enable(&dev->dev); device_enable_async_suspend(&dev->dev); dev->wakeup_prepared = false; -- cgit v1.2.3-70-g09d2