From b51306c63449d7f06ffa689036ba49eb46e898b5 Mon Sep 17 00:00:00 2001 From: Ajaykumar Hotchandani Date: Mon, 12 Dec 2011 13:57:36 +0530 Subject: [PATCH] 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. Acked-by: "Rafael J. Wysocki" Signed-off-by: Ajaykumar Hotchandani Signed-off-by: Yinghai Lu Signed-off-by: Jesse Barnes --- drivers/pci/hotplug/acpiphp_glue.c | 1 - drivers/pci/pci.c | 3 +++ 2 files changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c index 68360d5..9ddf69e 100644 --- a/drivers/pci/hotplug/acpiphp_glue.c +++ b/drivers/pci/hotplug/acpiphp_glue.c @@ -225,7 +225,6 @@ 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 4788413..faccb89 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 */ -- 2.7.4