Messages in this thread Patch in this message | | | Date | Fri, 28 Oct 2011 17:36:43 +0530 | From | Ajaykumar Hotchandani <> | Subject | Re: [PATCH] PCI: Set device power state to PCI_D0 for device without native PM support |
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On 10/27/2011 08:31 PM, Stefano Stabellini wrote: > On Thu, 27 Oct 2011, Ajaykumar Hotchandani wrote: >>> BTW I am OK with your patch. >> Should we revert 47e9037ac16637cd7f12b8790ea7ce6680e42168 (your changes >> in register_slot() ) >> I think, after this change, it's not needed. Or, am I missing some scenario? >> > I think you are right, 47e9037ac16637cd7f12b8790ea7ce6680e42168 is not > needed anymore, so I am OK with reverting it.
Thanks, following is updated patch.
[PATCH -v2] PCI: Set device power state to PCI_D0 for device without native PM support
During test of one IB card with guest VM, found that, msi is not initialized properly.
It turns out __write_msi_msg will do nothing if device current_state is not PCI_D0. And, that pci device does not have pm_cap in guest VM.
There is an error in setting of power state to PCI_D0 in pci_enable_device(), but error is not returned for this. Following is code flow: pci_enable_device() --> __pci_enable_device_flags() --> do_pci_enable_device() --> pci_set_power_state() --> __pci_start_power_transition() We have following condition inside __pci_start_power_transition(): if (platform_pci_power_manageable(dev)) { error = platform_pci_set_power_state(dev, state); if (!error) pci_update_current_state(dev, state); } else { error = -ENODEV; /* Fall back to PCI_D0 if native PM is not supported */ if (!dev->pm_cap) dev->current_state = PCI_D0; }
Here, from platform_pci_set_power_state(), acpi_pci_set_power_state() is getting called and that is failing with ENODEV because of following condition: if (!handle || ACPI_SUCCESS(acpi_get_handle(handle, "_EJ0",&tmp))) return -ENODEV;
Because of that, pci_update_current_state() is not getting called.
With this patch, if device power state can not be set via platform_pci_set_power_state and that device does not have native pm support, then PCI device power state will be set to PCI_D0.
-v2: This also reverts 47e9037ac16637cd7f12b8790ea7ce6680e42168, as it's not needed after this change.
Signed-off-by: Ajaykumar Hotchandani <ajaykumar.hotchandani@oracle.com> Signed-off-by: Yinghai Lu <yinghai.lu@oracle.com> --- drivers/pci/hotplug/acpiphp_glue.c | 1 - drivers/pci/pci.c | 3 +++ 2 files changed, 3 insertions(+), 1 deletions(-)
diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c index 2202857..11431c1 100644 --- a/drivers/pci/hotplug/acpiphp_glue.c +++ b/drivers/pci/hotplug/acpiphp_glue.c @@ -212,7 +212,6 @@ register_slot(acpi_handle handle, u32 lvl, void *context, void **rv)
pdev = pci_get_slot(pbus, PCI_DEVFN(device, function)); if (pdev) { - pdev->current_state = PCI_D0; slot->flags |= (SLOT_ENABLED | SLOT_POWEREDON); pci_dev_put(pdev); } diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index e9651f0..6866937 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -664,6 +664,9 @@ static int pci_platform_power_transition(struct pci_dev *dev, pci_power_t state) error = platform_pci_set_power_state(dev, state); if (!error) pci_update_current_state(dev, state); + /* Fall back to PCI_D0 if native PM is not supported */ + if (!dev->pm_cap) + dev->current_state = PCI_D0; } else { error = -ENODEV; /* Fall back to PCI_D0 if native PM is not supported */ -- 1.7.5.1
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