On Friday 01 January 2010, Rafael J. Wysocki wrote:
> On Sunday 27 December 2009, Rafael J. Wysocki wrote:
> > Hi,
> > 
> > The following (updated) series of patches provides preliminary run-time 
> > power
> > management support for PCI devices through ACPI and/or the native PCIe PME.
> > 
> > Some patches have been modified since the previous iteration, one patch has
> > been merged and there's one more.
> > 
> > I've tested this patchset with the native PCIe PME mechanism using the r8169
> > driver on the MSI Wind U-100 (see the last patch for details) and with the 
> > ACPI
> > mechanism using the e1000e driver on the Toshiba Portege R500 (the patch 
> > still
> > requires some work to be shown in public ;-)).
> 
> The e1000e patch is now in a better shape IMO, at least it worked for me in 
> all
> conditions I tested it, so it is appended below.

This one was actually buggy, as it triggered a netdevice.h BUG_ON() during
resume from suspend to RAM with network cable attached.

Appended is a new version that doesn't have this problem and enables runtime PM
in _probe(), so the device can be put into the low power state if _open()
hasn't been called yet (or after _close()).

Rafael

---
From: Rafael J. Wysocki <r...@sisk.pl>
Subject: PCI / PM / e1000e: Add basic runtime PM support (rev. 2)

Use the PCI run-time power management framework to add simplified
run-time PM support to the e1000e driver.  Namely, make the driver
suspend the device when the link is off and set it up for generating
wake-up event after the link has been detected again.

Based on a patch from Matthew Garrett.

Signed-off-by: Rafael J. Wysocki <r...@sisk.pl>
---
 drivers/net/e1000e/netdev.c |  130 +++++++++++++++++++++++++++++++++++---------
 1 file changed, 106 insertions(+), 24 deletions(-)

Index: linux-2.6/drivers/net/e1000e/netdev.c
===================================================================
--- linux-2.6.orig/drivers/net/e1000e/netdev.c
+++ linux-2.6/drivers/net/e1000e/netdev.c
@@ -44,6 +44,7 @@
 #include <linux/cpu.h>
 #include <linux/smp.h>
 #include <linux/pm_qos_params.h>
+#include <linux/pm_runtime.h>
 #include <linux/aer.h>
 
 #include "e1000.h"
@@ -3093,12 +3094,15 @@ static int e1000_open(struct net_device 
 {
        struct e1000_adapter *adapter = netdev_priv(netdev);
        struct e1000_hw *hw = &adapter->hw;
+       struct pci_dev *pdev = adapter->pdev;
        int err;
 
        /* disallow open during test */
        if (test_bit(__E1000_TESTING, &adapter->state))
                return -EBUSY;
 
+       pm_runtime_get_sync(&pdev->dev);
+
        netif_carrier_off(netdev);
 
        /* allocate transmit descriptors */
@@ -3162,6 +3166,8 @@ static int e1000_open(struct net_device 
        /* fire a link status change interrupt to start the watchdog */
        ew32(ICS, E1000_ICS_LSC);
 
+       pm_runtime_put_noidle(&pdev->dev);
+
        return 0;
 
 err_req_irq:
@@ -3172,6 +3178,7 @@ err_setup_rx:
        e1000e_free_tx_resources(adapter);
 err_setup_tx:
        e1000e_reset(adapter);
+       pm_runtime_put_noidle(&pdev->dev);
 
        return err;
 }
@@ -3190,9 +3197,15 @@ err_setup_tx:
 static int e1000_close(struct net_device *netdev)
 {
        struct e1000_adapter *adapter = netdev_priv(netdev);
+       struct pci_dev *pdev = adapter->pdev;
 
        WARN_ON(test_bit(__E1000_RESETTING, &adapter->state));
-       e1000e_down(adapter);
+
+       pm_runtime_get_sync(&pdev->dev);
+
+       if (!test_bit(__E1000_DOWN, &adapter->state))
+               e1000e_down(adapter);
+
        e1000_power_down_phy(adapter);
        e1000_free_irq(adapter);
 
@@ -3216,6 +3229,8 @@ static int e1000_close(struct net_device
        if (adapter->flags & FLAG_HAS_AMT)
                e1000_release_hw_control(adapter);
 
+       pm_runtime_put_noidle(&pdev->dev);
+
        return 0;
 }
 /**
@@ -3571,6 +3586,10 @@ static void e1000_watchdog_task(struct w
        if (link) {
                if (!netif_carrier_ok(netdev)) {
                        bool txb2b = 1;
+
+                       /* This is to cancel scheduled suspend requests. */
+                       pm_runtime_resume(netdev->dev.parent);
+
                        /* update snapshot of PHY registers on LSC */
                        e1000_phy_read_status(adapter);
                        mac->ops.get_link_up_info(&adapter->hw,
@@ -3686,6 +3705,8 @@ static void e1000_watchdog_task(struct w
 
                        if (adapter->flags & FLAG_RX_NEEDS_RESTART)
                                schedule_work(&adapter->reset_task);
+                       else
+                               pm_schedule_suspend(netdev->dev.parent, 100);
                }
        }
 
@@ -4489,13 +4510,15 @@ out:
        return retval;
 }
 
-static int __e1000_shutdown(struct pci_dev *pdev, bool *enable_wake)
+static int __e1000_shutdown(struct pci_dev *pdev, bool *enable_wake,
+                           bool runtime)
 {
        struct net_device *netdev = pci_get_drvdata(pdev);
        struct e1000_adapter *adapter = netdev_priv(netdev);
        struct e1000_hw *hw = &adapter->hw;
        u32 ctrl, ctrl_ext, rctl, status;
-       u32 wufc = adapter->wol;
+       /* Runtime suspend should only enable wakeup for link changes */
+       u32 wufc = runtime ? E1000_WUFC_LNKC : adapter->wol;
        int retval = 0;
 
        netif_device_detach(netdev);
@@ -4653,40 +4676,59 @@ static void e1000e_disable_l1aspm(struct
 }
 
 #ifdef CONFIG_PM
-static int e1000_suspend(struct pci_dev *pdev, pm_message_t state)
+static bool e1000e_pm_ready(struct e1000_adapter *adapter)
+{
+       return !!adapter->tx_ring->buffer_info;
+}
+
+static int e1000_idle(struct device *dev)
 {
+       struct pci_dev *pdev = to_pci_dev(dev);
+       struct net_device *netdev = pci_get_drvdata(pdev);
+       struct e1000_adapter *adapter = netdev_priv(netdev);
+
+       /*  If we're active, prevent the driver core from changing our state */
+       if (e1000e_pm_ready(adapter))
+               return -EBUSY;
+
+       pm_schedule_suspend(dev, MSEC_PER_SEC);
+       return 0;
+}
+
+static int e1000_suspend(struct device *dev)
+{
+       struct pci_dev *pdev = to_pci_dev(dev);
        int retval;
        bool wake;
 
-       retval = __e1000_shutdown(pdev, &wake);
+       retval = __e1000_shutdown(pdev, &wake, false);
        if (!retval)
                e1000_complete_shutdown(pdev, true, wake);
 
        return retval;
 }
 
-static int e1000_resume(struct pci_dev *pdev)
+static int e1000_runtime_suspend(struct device *dev)
 {
+       struct pci_dev *pdev = to_pci_dev(dev);
        struct net_device *netdev = pci_get_drvdata(pdev);
        struct e1000_adapter *adapter = netdev_priv(netdev);
-       struct e1000_hw *hw = &adapter->hw;
-       u32 err;
+       bool wake;
 
-       pci_set_power_state(pdev, PCI_D0);
-       pci_restore_state(pdev);
-       e1000e_disable_l1aspm(pdev);
+       if (e1000e_pm_ready(adapter))
+               return __e1000_shutdown(pdev, &wake, true);
 
-       err = pci_enable_device_mem(pdev);
-       if (err) {
-               dev_err(&pdev->dev,
-                       "Cannot enable PCI device from suspend\n");
-               return err;
-       }
+       return 0;
+}
 
-       pci_set_master(pdev);
+static int __e1000_resume(struct pci_dev *pdev)
+{
+       struct net_device *netdev = pci_get_drvdata(pdev);
+       struct e1000_adapter *adapter = netdev_priv(netdev);
+       struct e1000_hw *hw = &adapter->hw;
+       u32 err;
 
-       pci_enable_wake(pdev, PCI_D3hot, 0);
-       pci_enable_wake(pdev, PCI_D3cold, 0);
+       e1000e_disable_l1aspm(pdev);
 
        e1000e_set_interrupt_capability(adapter);
        if (netif_running(netdev)) {
@@ -4745,13 +4787,30 @@ static int e1000_resume(struct pci_dev *
 
        return 0;
 }
+
+static int e1000_resume(struct device *dev)
+{
+       return __e1000_resume(to_pci_dev(dev));
+}
+
+static int e1000_runtime_resume(struct device *dev)
+{
+       struct pci_dev *pdev = to_pci_dev(dev);
+       struct net_device *netdev = pci_get_drvdata(pdev);
+       struct e1000_adapter *adapter = netdev_priv(netdev);
+
+       if (e1000e_pm_ready(adapter))
+               return __e1000_resume(pdev);
+
+       return 0;
+}
 #endif
 
 static void e1000_shutdown(struct pci_dev *pdev)
 {
        bool wake = false;
 
-       __e1000_shutdown(pdev, &wake);
+       __e1000_shutdown(pdev, &wake, false);
 
        if (system_state == SYSTEM_POWER_OFF)
                e1000_complete_shutdown(pdev, false, wake);
@@ -5231,6 +5290,11 @@ static int __devinit e1000_probe(struct 
 
        e1000_print_device_info(adapter);
 
+       if (pci_dev_run_wake(pdev)) {
+               pm_runtime_set_active(&pdev->dev);
+               pm_runtime_enable(&pdev->dev);
+       }
+
        return 0;
 
 err_register:
@@ -5274,6 +5338,8 @@ static void __devexit e1000_remove(struc
        struct net_device *netdev = pci_get_drvdata(pdev);
        struct e1000_adapter *adapter = netdev_priv(netdev);
 
+       pm_runtime_get_sync(&pdev->dev);
+
        /*
         * flush_scheduled work may reschedule our watchdog task, so
         * explicitly disable watchdog tasks from being rescheduled
@@ -5294,6 +5360,12 @@ static void __devexit e1000_remove(struc
 
        unregister_netdev(netdev);
 
+       if (pci_dev_run_wake(pdev)) {
+               pm_runtime_disable(&pdev->dev);
+               pm_runtime_set_suspended(&pdev->dev);
+       }
+       pm_runtime_put_noidle(&pdev->dev);
+
        /*
         * Release control of h/w to f/w.  If f/w is AMT enabled, this
         * would have already happened in close and is redundant.
@@ -5393,6 +5465,18 @@ static struct pci_device_id e1000_pci_tb
 };
 MODULE_DEVICE_TABLE(pci, e1000_pci_tbl);
 
+static const struct dev_pm_ops e1000_pm_ops = {
+       .suspend  = e1000_suspend,
+       .resume   = e1000_resume,
+       .freeze = e1000_suspend,
+       .thaw = e1000_resume,
+       .poweroff = e1000_suspend,
+       .restore = e1000_resume,
+       .runtime_suspend = e1000_runtime_suspend,
+       .runtime_resume = e1000_runtime_resume,
+       .runtime_idle = e1000_idle,
+};
+
 /* PCI Device API Driver */
 static struct pci_driver e1000_driver = {
        .name     = e1000e_driver_name,
@@ -5400,9 +5484,7 @@ static struct pci_driver e1000_driver = 
        .probe    = e1000_probe,
        .remove   = __devexit_p(e1000_remove),
 #ifdef CONFIG_PM
-       /* Power Management Hooks */
-       .suspend  = e1000_suspend,
-       .resume   = e1000_resume,
+       .driver.pm = &e1000_pm_ops,
 #endif
        .shutdown = e1000_shutdown,
        .err_handler = &e1000_err_handler

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