@@ -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);
@@ -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);
}
@@ -406,6 +406,7 @@ static ssize_t d3cold_allowed_store(struct device *dev,
return -EINVAL;
pdev->d3cold_allowed = !!val;
+ pci_bridge_d3_device_changed(pdev);
pm_runtime_resume(dev);
return count;
@@ -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>
@@ -2156,6 +2157,160 @@ 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:
+ /*
+ * 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 +2344,7 @@ 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;
@@ -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)
{
@@ -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);
}
@@ -379,7 +379,7 @@ 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);
@@ -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)
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. If the above restrictions are met we set 'bridge_d3' to true and transition the port to D3 when system is suspended. Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> --- drivers/pci/bus.c | 1 + drivers/pci/pci-driver.c | 7 +- drivers/pci/pci-sysfs.c | 1 + drivers/pci/pci.c | 156 ++++++++++++++++++++++++++++++++++++++++++++ drivers/pci/pci.h | 2 + drivers/pci/remove.c | 2 + drivers/usb/host/xhci-pci.c | 2 +- include/linux/pci.h | 3 + 8 files changed, 172 insertions(+), 2 deletions(-)