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| author | Lukas Wunner <lukas@wunner.de> | 2016-10-28 10:52:06 +0200 |
|---|---|---|
| committer | Bjorn Helgaas <bhelgaas@google.com> | 2016-11-17 18:46:06 -0600 |
| commit | c6a6330706148e7d5265c3dd658d25843c83390f (patch) | |
| tree | 3a6084b514e490879976faa75fb9efc9f8b7638a | |
| parent | e8559b7100324494acbde6e26bcdc6a5a5b4a4ed (diff) | |
| download | lwn-c6a6330706148e7d5265c3dd658d25843c83390f.tar.gz lwn-c6a6330706148e7d5265c3dd658d25843c83390f.zip | |
PCI: Activate runtime PM on a PCIe port only if it can suspend
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.
Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
| -rw-r--r-- | drivers/pci/pci.c | 2 | ||||
| -rw-r--r-- | drivers/pci/pci.h | 1 | ||||
| -rw-r--r-- | 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 4a7f6f54d669..720f7e27c3a8 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -2230,7 +2230,7 @@ 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 27048bb88783..ffffef37ab61 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 79327cc14e7d..1ae712cb22ec 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); |