PCI/PM: Keep parent bridge active when probing device
This patch fixes the following bug: http://marc.info/?l=linux-pci&m=134329923124234&w=2 The root cause of the bug is as follow. If a device is not bound with the corresponding driver, the device runtime PM will be disabled and the device will be put into suspended state. So that, the bridge/PCIe port connected to it may be put into suspended and low power state. When do probing for the device later, because the bridge/PCIe port connected to it is in low power state, the IO access to device may fail. To solve the issue, the bridge/PCIe port connected to the device is put into active state before probing. Reported-by: Bjorn Mork <bjorn@mork.no> Signed-off-by: Huang Ying <ying.huang@intel.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Rafael J. Wysocki <rjw@sisk.pl>
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@ -280,8 +280,12 @@ static long local_pci_probe(void *_ddi)
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{
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struct drv_dev_and_id *ddi = _ddi;
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struct device *dev = &ddi->dev->dev;
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struct device *parent = dev->parent;
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int rc;
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/* The parent bridge must be in active state when probing */
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if (parent)
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pm_runtime_get_sync(parent);
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/* Unbound PCI devices are always set to disabled and suspended.
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* During probe, the device is set to enabled and active and the
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* usage count is incremented. If the driver supports runtime PM,
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@ -298,6 +302,8 @@ static long local_pci_probe(void *_ddi)
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pm_runtime_set_suspended(dev);
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pm_runtime_put_noidle(dev);
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}
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if (parent)
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pm_runtime_put(parent);
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return rc;
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}
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