On Friday, August 03, 2012, Huang Ying wrote:
> 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 <bj...@mork.no>
> Signed-off-by: Huang Ying <ying.hu...@intel.com>
Reviewed-by: Rafael J. Wysocki <r...@sisk.pl>
> ---
> drivers/pci/pci-driver.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> --- a/drivers/pci/pci-driver.c
> +++ b/drivers/pci/pci-driver.c
> @@ -280,8 +280,12 @@ static long local_pci_probe(void *_ddi)
> {
> struct drv_dev_and_id *ddi = _ddi;
> struct device *dev = &ddi->dev->dev;
> + struct device *parent = dev->parent;
> int rc;
>
> + /* The parent bridge must be in active state when probing */
> + if (parent)
> + pm_runtime_get_sync(parent);
> /* Unbound PCI devices are always set to disabled and suspended.
> * During probe, the device is set to enabled and active and the
> * usage count is incremented. If the driver supports runtime PM,
> @@ -298,6 +302,8 @@ static long local_pci_probe(void *_ddi)
> pm_runtime_set_suspended(dev);
> pm_runtime_put_noidle(dev);
> }
> + if (parent)
> + pm_runtime_put(parent);
> return rc;
> }
>
>
>
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