Currently the Linux PCI core does not touch power state of PCI bridges and
PCIe ports when system suspend is entered. Leaving them in D0 consumes
power which is not good thing in portable devices such as laptops. This may
also prevent the CPU from entering deeper C-states.
With recent PCIe hardware we can power down the ports to save power given
that we take into account few restrictions:
- The PCIe port hardware is recent enough, starting from 2015.
- Devices connected to PCIe ports are effectively in D3cold once the port
is moved to D3 (the config space is not accessible anymore and the link
may be powered down).
- Devices behind the PCIe port need to be allowed to transition to D3cold
and back. There is a way both drivers and userspace can forbid this.
- If the device behind the PCIe port is capable of waking the system it
needs to be able to do so from D3cold.
This patch adds a new flag to struct pci_device called 'bridge_d3'. This
flag is set and cleared by the PCI core whenever there is a change in power
management state of any of the devices behind the PCIe port (we provide
helper functions that should be used to change state of the device, like
pci_d3cold_disable()). When system later on is suspended we only need to
check this flag and if it is true transition the port to D3 otherwise we
leave it in D0.
Also provide override mechanism via command line parameter
"pcie_port_pm=[off|force]" that can be used to disable or enable the
feature regardless of the BIOS manufacturing date.
Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
---
Documentation/kernel-parameters.txt | 4 +
drivers/pci/bus.c | 1 +
drivers/pci/pci-driver.c | 10 +-
drivers/pci/pci-sysfs.c | 5 +
drivers/pci/pci.c | 176 ++++++++++++++++++++++++++++++++++++
drivers/pci/pci.h | 2 +
drivers/pci/remove.c | 2 +
drivers/usb/host/xhci-pci.c | 2 +-
include/linux/pci.h | 3 +
9 files changed, 200 insertions(+), 5 deletions(-)
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 0b3de80ec8f6..90e1f43760be 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -3008,6 +3008,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
compat Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe
ports driver.
+ pcie_port_pm= [PCIE] PCIe port power management handling:
+ off Disable power management of all PCIe ports
+ force Forcibly enable power management of all PCIe ports
+
pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
nomsi Do not use MSI for native PCIe PME signaling (this makes
all PCIe root ports use INTx for all services).
diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c
index 6c9f5467bc5f..b1738162d69a 100644
--- a/drivers/pci/bus.c
+++ b/drivers/pci/bus.c
@@ -291,6 +291,7 @@ void pci_bus_add_device(struct pci_dev *dev)
pci_fixup_device(pci_fixup_final, dev);
pci_create_sysfs_dev_files(dev);
pci_proc_attach_device(dev);
+ pci_bridge_d3_device_changed(dev);
dev->match_driver = true;
retval = device_attach(&dev->dev);
diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index d7ffd66814bb..e3ece0e25fa3 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -777,7 +777,12 @@ static int pci_pm_suspend_noirq(struct device *dev)
if (!pci_dev->state_saved) {
pci_save_state(pci_dev);
- if (!pci_has_subordinate(pci_dev))
+ /*
+ * Check if given device can go to low power state. Currently
+ * we allow normal PCI devices and PCI bridges if their
+ * bridge_d3 is set.
+ */
+ if (!pci_has_subordinate(pci_dev) || pci_dev->bridge_d3)
pci_prepare_to_sleep(pci_dev);
}
@@ -1144,7 +1149,6 @@ static int pci_pm_runtime_suspend(struct device *dev)
return -ENOSYS;
pci_dev->state_saved = false;
- pci_dev->no_d3cold = false;
error = pm->runtime_suspend(dev);
if (error) {
/*
@@ -1161,8 +1165,6 @@ static int pci_pm_runtime_suspend(struct device *dev)
return error;
}
- if (!pci_dev->d3cold_allowed)
- pci_dev->no_d3cold = true;
pci_fixup_device(pci_fixup_suspend, pci_dev);
diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index 342b6918bbde..1a0854be5b18 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -406,6 +406,11 @@ static ssize_t d3cold_allowed_store(struct device *dev,
return -EINVAL;
pdev->d3cold_allowed = !!val;
+ if (pdev->d3cold_allowed)
+ pci_d3cold_enable(pdev);
+ else
+ pci_d3cold_disable(pdev);
+
pm_runtime_resume(dev);
return count;
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 25e0327d4429..69878d5e2c2f 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -9,6 +9,7 @@
#include <linux/kernel.h>
#include <linux/delay.h>
+#include <linux/dmi.h>
#include <linux/init.h>
#include <linux/of.h>
#include <linux/of_pci.h>
@@ -101,6 +102,21 @@ unsigned int pcibios_max_latency = 255;
/* If set, the PCIe ARI capability will not be used. */
static bool pcie_ari_disabled;
+/* Disable bridge_d3 for all PCIe ports */
+static bool pci_bridge_d3_disable;
+/* Force bridge_d3 for all PCIe ports */
+static bool pci_bridge_d3_force;
+
+static int __init pcie_port_pm_setup(char *str)
+{
+ if (!strcmp(str, "off"))
+ pci_bridge_d3_disable = true;
+ else if (!strcmp(str, "force"))
+ pci_bridge_d3_force = true;
+ return 1;
+}
+__setup("pcie_port_pm=", pcie_port_pm_setup);
+
/**
* pci_bus_max_busnr - returns maximum PCI bus number of given bus' children
* @bus: pointer to PCI bus structure to search
@@ -2156,6 +2172,165 @@ void pci_config_pm_runtime_put(struct pci_dev *pdev)
}
/**
+ * pci_bridge_d3_possible - Is it possible to move the bridge to D3
+ * @bridge: Bridge to check
+ *
+ * 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)
+{
+ unsigned int year;
+
+ if (!pci_is_pcie(bridge))
+ return false;
+
+ switch (pci_pcie_type(bridge)) {
+ case PCI_EXP_TYPE_ROOT_PORT:
+ case PCI_EXP_TYPE_UPSTREAM:
+ case PCI_EXP_TYPE_DOWNSTREAM:
+ if (pci_bridge_d3_disable)
+ return false;
+ if (pci_bridge_d3_force)
+ return true;
+
+ /*
+ * PCIe ports from 2015 and newer should be capable of
+ * entering D3.
+ */
+ if (dmi_get_date(DMI_BIOS_DATE, &year, NULL, NULL) &&
+ year >= 2015) {
+ return true;
+ }
+ break;
+ }
+
+ return false;
+}
+
+static int pci_dev_check_d3cold(struct pci_dev *dev, void *data)
+{
+ bool *d3cold_ok = data;
+
+ /*
+ * The device needs to be allowed to go D3cold and if it is wake
+ * capable to do so from D3cold. If the device is bridge then it
+ * needs to have D3 allowed.
+ */
+ if (dev->no_d3cold || !dev->d3cold_allowed)
+ *d3cold_ok = false;
+ if (device_may_wakeup(&dev->dev) && !pci_pme_capable(dev, PCI_D3cold))
+ *d3cold_ok = false;
+ if (pci_has_subordinate(dev) && !dev->bridge_d3)
+ *d3cold_ok = false;
+
+ return !*d3cold_ok;
+}
+
+/*
+ * pci_bridge_d3_update - Update bridge D3 capabilities
+ * @dev: PCI device which is changed
+ * @remove: Is the device being removed
+ *
+ * Updates upstream bridge PM capabilities accordingly depending on if the
+ * device PM configuration was changed or the device is being removed. The
+ * change is also propagated upstream.
+ */
+static void pci_bridge_d3_update(struct pci_dev *dev, bool remove)
+{
+ struct pci_dev *bridge;
+ bool d3cold_ok = true;
+
+ bridge = pci_upstream_bridge(dev);
+ if (!bridge || !pci_bridge_d3_possible(bridge))
+ return;
+
+ pci_dev_get(bridge);
+ /*
+ * If the device is removed we do not care about its D3cold
+ * capabilities.
+ */
+ if (!remove)
+ pci_dev_check_d3cold(dev, &d3cold_ok);
+
+ if (d3cold_ok) {
+ /*
+ * We need to go through all children to find out if all of
+ * them can still go to D3cold.
+ */
+ pci_walk_bus(bridge->subordinate, pci_dev_check_d3cold,
+ &d3cold_ok);
+ }
+
+ if (bridge->bridge_d3 != d3cold_ok) {
+ bridge->bridge_d3 = d3cold_ok;
+ /* Propagate change to upstream bridges */
+ pci_bridge_d3_update(bridge, false);
+ }
+
+ pci_dev_put(bridge);
+}
+
+/**
+ * pci_bridge_d3_device_changed - Update bridge D3 capabilities on change
+ * @dev: PCI device that was changed
+ *
+ * If a device is added or its PM configuration, such as is it allowed to
+ * enter D3cold, is changed this function updates upstream bridge PM
+ * capabilities accordingly.
+ */
+void pci_bridge_d3_device_changed(struct pci_dev *dev)
+{
+ pci_bridge_d3_update(dev, false);
+}
+
+/**
+ * pci_bridge_d3_device_removed - Update bridge D3 capabilities on remove
+ * @dev: PCI device being removed
+ *
+ * Function updates upstream bridge PM capabilities based on other devices
+ * still left on the bus.
+ */
+void pci_bridge_d3_device_removed(struct pci_dev *dev)
+{
+ pci_bridge_d3_update(dev, true);
+}
+
+/**
+ * pci_d3cold_enable - Enable D3cold for device
+ * @dev: PCI device to handle
+ *
+ * This function can be used in drivers to enable D3cold from the device
+ * they handle. It also updates upstream PCI bridge PM capabilities
+ * accordingly.
+ */
+void pci_d3cold_enable(struct pci_dev *dev)
+{
+ if (dev->no_d3cold) {
+ dev->no_d3cold = false;
+ pci_bridge_d3_device_changed(dev);
+ }
+}
+EXPORT_SYMBOL_GPL(pci_d3cold_enable);
+
+/**
+ * pci_d3cold_disable - Disable D3cold for device
+ * @dev: PCI device to handle
+ *
+ * This function can be used in drivers to disable D3cold from the device
+ * they handle. It also updates upstream PCI bridge PM capabilities
+ * accordingly.
+ */
+void pci_d3cold_disable(struct pci_dev *dev)
+{
+ if (!dev->no_d3cold) {
+ dev->no_d3cold = true;
+ pci_bridge_d3_device_changed(dev);
+ }
+}
+EXPORT_SYMBOL_GPL(pci_d3cold_disable);
+
+/**
* pci_pm_init - Initialize PM functions of given PCI device
* @dev: PCI device to handle.
*/
@@ -2189,6 +2364,7 @@ void pci_pm_init(struct pci_dev *dev)
dev->pm_cap = pm;
dev->d3_delay = PCI_PM_D3_WAIT;
dev->d3cold_delay = PCI_PM_D3COLD_WAIT;
+ dev->bridge_d3 = pci_bridge_d3_possible(dev);
dev->d3cold_allowed = true;
dev->d1_support = false;
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index a814bbb80fcb..1d247e39da0a 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -82,6 +82,8 @@ 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);
+void pci_bridge_d3_device_changed(struct pci_dev *dev);
+void pci_bridge_d3_device_removed(struct pci_dev *dev);
static inline void pci_wakeup_event(struct pci_dev *dev)
{
diff --git a/drivers/pci/remove.c b/drivers/pci/remove.c
index 8982026637d5..d1ef7acf6930 100644
--- a/drivers/pci/remove.c
+++ b/drivers/pci/remove.c
@@ -96,6 +96,8 @@ static void pci_remove_bus_device(struct pci_dev *dev)
dev->subordinate = NULL;
}
+ pci_bridge_d3_device_removed(dev);
+
pci_destroy_dev(dev);
}
diff --git a/drivers/usb/host/xhci-pci.c b/drivers/usb/host/xhci-pci.c
index 48672fac7ff3..ac352fe391f4 100644
--- a/drivers/usb/host/xhci-pci.c
+++ b/drivers/usb/host/xhci-pci.c
@@ -382,7 +382,7 @@ static int xhci_pci_suspend(struct usb_hcd *hcd, bool do_wakeup)
* need to have the registers polled during D3, so avoid D3cold.
*/
if (xhci->quirks & XHCI_COMP_MODE_QUIRK)
- pdev->no_d3cold = true;
+ pci_d3cold_disable(pdev);
if (xhci->quirks & XHCI_PME_STUCK_QUIRK)
xhci_pme_quirk(hcd);
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 932ec74909c6..aa7d586710c0 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -296,6 +296,7 @@ struct pci_dev {
unsigned int d2_support:1; /* Low power state D2 is supported */
unsigned int no_d1d2:1; /* D1 and D2 are forbidden */
unsigned int no_d3cold:1; /* D3cold is forbidden */
+ unsigned int bridge_d3:1; /* Allow D3 for bridge */
unsigned int d3cold_allowed:1; /* D3cold is allowed by user */
unsigned int mmio_always_on:1; /* disallow turning off io/mem
decoding during bar sizing */
@@ -1085,6 +1086,8 @@ int pci_back_from_sleep(struct pci_dev *dev);
bool pci_dev_run_wake(struct pci_dev *dev);
bool pci_check_pme_status(struct pci_dev *dev);
void pci_pme_wakeup_bus(struct pci_bus *bus);
+void pci_d3cold_enable(struct pci_dev *dev);
+void pci_d3cold_disable(struct pci_dev *dev);
static inline int pci_enable_wake(struct pci_dev *dev, pci_power_t state,
bool enable)
--
2.8.0.rc3
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