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@xxxxxxxxxx>
Signed-off-by: Yinghai Lu <yinghai.lu@xxxxxxxxxx>
---
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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