[PATCH][RFC] e1000e: Add basic runtime PM support (rev. 2) (was: [PATCH 0/12] PCI run-time PM support (rev. 2))

["Rafael J. Wysocki" <rjw@sisk.pl>]

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 <rjw@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 <rjw@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