diff mbox

[v6,3/5] PCI: Power on bridges before scanning new devices

Message ID 1464855435-32960-4-git-send-email-mika.westerberg@linux.intel.com (mailing list archive)
State New, archived
Delegated to: Bjorn Helgaas
Headers show

Commit Message

Mika Westerberg June 2, 2016, 8:17 a.m. UTC
When a PCI device is removed through sysfs interface the upstream bridge
(PCIe port) can be runtime suspended if it was the last device on that bus.
Now, if the bridge is in D3 we cannot find devices below the bridge
anymore.  For example following fails to find the removed device again:

  # echo 1 > /sys/bus/pci/devices/0000:00:01.0/0000:01:00.0/remove
  # echo 1 > /sys/bus/pci/devices/0000:00:01.0/rescan

Where 0000:00:01.0 is the bridge device.

In order to be able to rescan devices below the bridge add
pm_runtime_get_sync()/pm_runtime_put() calls to pci_scan_bridge().  This
should keep bridges powered on while their children devices are being
scanned.

Reported-by: Peter Wu <peter@lekensteyn.nl>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
---
 drivers/pci/probe.c | 9 +++++++++
 1 file changed, 9 insertions(+)

Comments

Rafael J. Wysocki June 2, 2016, 12:26 p.m. UTC | #1
On Thu, Jun 2, 2016 at 10:17 AM, Mika Westerberg
<mika.westerberg@linux.intel.com> wrote:
> When a PCI device is removed through sysfs interface the upstream bridge
> (PCIe port) can be runtime suspended if it was the last device on that bus.
> Now, if the bridge is in D3 we cannot find devices below the bridge
> anymore.  For example following fails to find the removed device again:
>
>   # echo 1 > /sys/bus/pci/devices/0000:00:01.0/0000:01:00.0/remove
>   # echo 1 > /sys/bus/pci/devices/0000:00:01.0/rescan
>
> Where 0000:00:01.0 is the bridge device.
>
> In order to be able to rescan devices below the bridge add
> pm_runtime_get_sync()/pm_runtime_put() calls to pci_scan_bridge().  This
> should keep bridges powered on while their children devices are being
> scanned.
>
> Reported-by: Peter Wu <peter@lekensteyn.nl>
> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

> ---
>  drivers/pci/probe.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
>
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 8e3ef720997d..11a802daf242 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -16,6 +16,7 @@
>  #include <linux/aer.h>
>  #include <linux/acpi.h>
>  #include <linux/irqdomain.h>
> +#include <linux/pm_runtime.h>
>  #include "pci.h"
>
>  #define CARDBUS_LATENCY_TIMER  176     /* secondary latency timer */
> @@ -832,6 +833,12 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max, int pass)
>         u8 primary, secondary, subordinate;
>         int broken = 0;
>
> +       /*
> +        * Make sure the bridge is powered on to be able to access config
> +        * space of devices below it.
> +        */
> +       pm_runtime_get_sync(&dev->dev);
> +
>         pci_read_config_dword(dev, PCI_PRIMARY_BUS, &buses);
>         primary = buses & 0xFF;
>         secondary = (buses >> 8) & 0xFF;
> @@ -1012,6 +1019,8 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max, int pass)
>  out:
>         pci_write_config_word(dev, PCI_BRIDGE_CONTROL, bctl);
>
> +       pm_runtime_put(&dev->dev);
> +
>         return max;
>  }
>  EXPORT_SYMBOL(pci_scan_bridge);
> --
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diff mbox

Patch

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 8e3ef720997d..11a802daf242 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -16,6 +16,7 @@ 
 #include <linux/aer.h>
 #include <linux/acpi.h>
 #include <linux/irqdomain.h>
+#include <linux/pm_runtime.h>
 #include "pci.h"
 
 #define CARDBUS_LATENCY_TIMER	176	/* secondary latency timer */
@@ -832,6 +833,12 @@  int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max, int pass)
 	u8 primary, secondary, subordinate;
 	int broken = 0;
 
+	/*
+	 * Make sure the bridge is powered on to be able to access config
+	 * space of devices below it.
+	 */
+	pm_runtime_get_sync(&dev->dev);
+
 	pci_read_config_dword(dev, PCI_PRIMARY_BUS, &buses);
 	primary = buses & 0xFF;
 	secondary = (buses >> 8) & 0xFF;
@@ -1012,6 +1019,8 @@  int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max, int pass)
 out:
 	pci_write_config_word(dev, PCI_BRIDGE_CONTROL, bctl);
 
+	pm_runtime_put(&dev->dev);
+
 	return max;
 }
 EXPORT_SYMBOL(pci_scan_bridge);