Currently pcie_portdrv_probe() activates runtime PM on a PCIe port even
if it will never actually suspend because the BIOS is too old or the
"pcie_port_pm=off" option was specified on the kernel command line.
A few CPU cycles can be saved by not activating runtime PM at all in
these cases, because rpm_idle() and rpm_suspend() will bail out right
at the beginning when calling rpm_check_suspend_allowed(), instead of
carrying out various locking and assignments, invoking rpm_callback(),
getting back -EBUSY and rolling everything back.
The conditions checked in pci_bridge_d3_possible() are all static, they
never change during uptime of the system, hence it's safe to call this
to determine if runtime PM should be activated.
No functional change intended.
Cc: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
Cc: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Signed-off-by: Lukas Wunner <lukas@xxxxxxxxx>
---
drivers/pci/pci.c | 2 +-
drivers/pci/pci.h | 1 +
drivers/pci/pcie/portdrv_pci.c | 5 +++--
3 files changed, 5 insertions(+), 3 deletions(-)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index bc60f2c..854d185 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -2226,7 +2226,7 @@ void pci_config_pm_runtime_put(struct pci_dev *pdev)
* This function checks if it is possible to move the bridge to D3.
* Currently we only allow D3 for recent enough PCIe ports.
*/
-static bool pci_bridge_d3_possible(struct pci_dev *bridge)
+bool pci_bridge_d3_possible(struct pci_dev *bridge)
{
unsigned int year;
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 27048bb..ffffef3 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -85,6 +85,7 @@ void pci_pm_init(struct pci_dev *dev);
void pci_ea_init(struct pci_dev *dev);
void pci_allocate_cap_save_buffers(struct pci_dev *dev);
void pci_free_cap_save_buffers(struct pci_dev *dev);
+bool pci_bridge_d3_possible(struct pci_dev *dev);
void pci_bridge_d3_update(struct pci_dev *dev);
static inline void pci_wakeup_event(struct pci_dev *dev)
diff --git a/drivers/pci/pcie/portdrv_pci.c b/drivers/pci/pcie/portdrv_pci.c
index 79327cc..1ae712c 100644
--- a/drivers/pci/pcie/portdrv_pci.c
+++ b/drivers/pci/pcie/portdrv_pci.c
@@ -19,6 +19,7 @@
#include <linux/dmi.h>
#include <linux/pci-aspm.h>
+#include "../pci.h"
#include "portdrv.h"
#include "aer/aerdrv.h"
@@ -157,7 +158,7 @@ static int pcie_portdrv_probe(struct pci_dev *dev,
* subordinate devices). We can't be sure for native PCIe hotplug
* either so prevent that as well.
*/
- if (!dev->is_hotplug_bridge) {
+ if (pci_bridge_d3_possible(dev) && !dev->is_hotplug_bridge) {
/*
* Keep the port resumed 100ms to make sure things like
* config space accesses from userspace (lspci) will not
@@ -175,7 +176,7 @@ static int pcie_portdrv_probe(struct pci_dev *dev,
static void pcie_portdrv_remove(struct pci_dev *dev)
{
- if (!dev->is_hotplug_bridge) {
+ if (pci_bridge_d3_possible(dev) && !dev->is_hotplug_bridge) {
pm_runtime_forbid(&dev->dev);
pm_runtime_get_noresume(&dev->dev);
pm_runtime_dont_use_autosuspend(&dev->dev);
--
2.9.3
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