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[BUGFIX 2/4] PCI/PM: Keep parent bridge active when probing device

 

 

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ying.huang at intel

Aug 2, 2012, 11:30 PM

Post #1 of 2 (105 views)
Permalink
[BUGFIX 2/4] 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 [at] mork>
Signed-off-by: Huang Ying <ying.huang [at] intel>
---
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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rjw at sisk

Aug 4, 2012, 2:48 PM

Post #2 of 2 (96 views)
Permalink
Re: [BUGFIX 2/4] PCI/PM: Keep parent bridge active when probing device [In reply to]

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 <bjorn [at] mork>
> Signed-off-by: Huang Ying <ying.huang [at] intel>

Reviewed-by: Rafael J. Wysocki <rjw [at] sisk>

> ---
> 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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