USB: OHCI avoids root hub timer polling

This teaches OHCI to use the root hub status change (RHSC) IRQ, bypassing
root hub timers most of the time and switching over to the "new" root hub
polling scheme.  It's complicated by the fact that implementations of OHCI
trigger and ack that IRQ differently (the spec is vague there).

Avoiding root hub timers helps mechanisms like "dynamic tick" leave the
CPU in lowpower modes for longer intervals.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/host/ohci-at91.c

@@ -239,7 +239,7 @@ static const struct hc_driver ohci_at91_hc_driver = {
 	 */
 	.hub_status_data =	ohci_hub_status_data,
 	.hub_control =		ohci_hub_control,
-
+	.hub_irq_enable =	ohci_rhsc_enable,
 #ifdef CONFIG_PM
 	.bus_suspend =		ohci_bus_suspend,
 	.bus_resume =		ohci_bus_resume,

drivers/usb/host/ohci-au1xxx.c

@@ -268,10 +268,6 @@ static const struct hc_driver ohci_au1xxx_hc_driver = {
 	 * basic lifecycle operations
 	 */
 	.start =		ohci_au1xxx_start,
-#ifdef	CONFIG_PM
-	/* suspend:		ohci_au1xxx_suspend,  -- tbd */
-	/* resume:		ohci_au1xxx_resume,   -- tbd */
-#endif /*CONFIG_PM*/
 	.stop =			ohci_stop,
 
 	/*
@@ -291,6 +287,7 @@ static const struct hc_driver ohci_au1xxx_hc_driver = {
 	 */
 	.hub_status_data =	ohci_hub_status_data,
 	.hub_control =		ohci_hub_control,
+	.hub_irq_enable =	ohci_rhsc_enable,
 #ifdef	CONFIG_PM
 	.bus_suspend =		ohci_bus_suspend,
 	.bus_resume =		ohci_bus_resume,

drivers/usb/host/ohci-dbg.c

@@ -667,6 +667,11 @@ show_registers (struct class_device *class_dev, char *buf)
 	size -= temp;
 	next += temp;
 
+	temp = scnprintf (next, size, "hub poll timer %s\n",
+			ohci_to_hcd(ohci)->poll_rh ? "ON" : "off");
+	size -= temp;
+	next += temp;
+
 	/* roothub */
 	ohci_dump_roothub (ohci, 1, &next, &size);
 

drivers/usb/host/ohci-ep93xx.c

@@ -134,6 +134,7 @@ static struct hc_driver ohci_ep93xx_hc_driver = {
 	.get_frame_number	= ohci_get_frame,
 	.hub_status_data	= ohci_hub_status_data,
 	.hub_control		= ohci_hub_control,
+	.hub_irq_enable		= ohci_rhsc_enable,
 #ifdef CONFIG_PM
 	.bus_suspend		= ohci_bus_suspend,
 	.bus_resume		= ohci_bus_resume,

drivers/usb/host/ohci-hcd.c

@@ -101,7 +101,7 @@
 
 #include "../core/hcd.h"
 
-#define DRIVER_VERSION "2005 April 22"
+#define DRIVER_VERSION "2006 August 04"
 #define DRIVER_AUTHOR "Roman Weissgaerber, David Brownell"
 #define DRIVER_DESC "USB 1.1 'Open' Host Controller (OHCI) Driver"
 
@@ -110,9 +110,10 @@
 #undef OHCI_VERBOSE_DEBUG	/* not always helpful */
 
 /* For initializing controller (mask in an HCFS mode too) */
-#define	OHCI_CONTROL_INIT 	OHCI_CTRL_CBSR
+#define	OHCI_CONTROL_INIT	OHCI_CTRL_CBSR
 #define	OHCI_INTR_INIT \
-	(OHCI_INTR_MIE | OHCI_INTR_UE | OHCI_INTR_RD | OHCI_INTR_WDH)
+		(OHCI_INTR_MIE | OHCI_INTR_RHSC | OHCI_INTR_UE \
+		| OHCI_INTR_RD | OHCI_INTR_WDH)
 
 #ifdef __hppa__
 /* On PA-RISC, PDC can leave IR set incorrectly; ignore it there. */
@@ -128,6 +129,8 @@
 
 static const char	hcd_name [] = "ohci_hcd";
 
+#define	STATECHANGE_DELAY	msecs_to_jiffies(300)
+
 #include "ohci.h"
 
 static void ohci_dump (struct ohci_hcd *ohci, int verbose);
@@ -446,7 +449,6 @@ static int ohci_init (struct ohci_hcd *ohci)
 
 	disable (ohci);
 	ohci->regs = hcd->regs;
-	ohci->next_statechange = jiffies;
 
 	/* REVISIT this BIOS handshake is now moved into PCI "quirks", and
 	 * was never needed for most non-PCI systems ... remove the code?
@@ -637,18 +639,22 @@ static int ohci_run (struct ohci_hcd *ohci)
 		return -EOVERFLOW;
 	}
 
- 	/* start controller operations */
+	/* use rhsc irqs after khubd is fully initialized */
+	hcd->poll_rh = 1;
+	hcd->uses_new_polling = 1;
+
+	/* start controller operations */
 	ohci->hc_control &= OHCI_CTRL_RWC;
- 	ohci->hc_control |= OHCI_CONTROL_INIT | OHCI_USB_OPER;
- 	ohci_writel (ohci, ohci->hc_control, &ohci->regs->control);
+	ohci->hc_control |= OHCI_CONTROL_INIT | OHCI_USB_OPER;
+	ohci_writel (ohci, ohci->hc_control, &ohci->regs->control);
 	hcd->state = HC_STATE_RUNNING;
 
 	/* wake on ConnectStatusChange, matching external hubs */
 	ohci_writel (ohci, RH_HS_DRWE, &ohci->regs->roothub.status);
 
 	/* Choose the interrupts we care about now, others later on demand */
 	mask = OHCI_INTR_INIT;
-	ohci_writel (ohci, mask, &ohci->regs->intrstatus);
+	ohci_writel (ohci, ~0, &ohci->regs->intrstatus);
 	ohci_writel (ohci, mask, &ohci->regs->intrenable);
 
 	/* handle root hub init quirks ... */
@@ -672,6 +678,7 @@ static int ohci_run (struct ohci_hcd *ohci)
 	// flush those writes
 	(void) ohci_readl (ohci, &ohci->regs->control);
 
+	ohci->next_statechange = jiffies + STATECHANGE_DELAY;
 	spin_unlock_irq (&ohci->lock);
 
 	// POTPGT delay is bits 24-31, in 2 ms units.
@@ -709,7 +716,23 @@ static irqreturn_t ohci_irq (struct usb_hcd *hcd, struct pt_regs *ptregs)
 	/* interrupt for some other device? */
 	} else if ((ints &= ohci_readl (ohci, &regs->intrenable)) == 0) {
 		return IRQ_NOTMINE;
-	} 
+	}
+
+	/* NOTE:  vendors didn't always make the same implementation
+	 * choices for RHSC.  Sometimes it triggers on an edge (like
+	 * setting and maybe clearing a port status change bit); and
+	 * it's level-triggered on other silicon, active until khubd
+	 * clears all active port status change bits.  Poll by timer
+	 * til it's fully debounced and the difference won't matter.
+	 */
+	if (ints & OHCI_INTR_RHSC) {
+		ohci_vdbg (ohci, "rhsc\n");
+		ohci_writel (ohci, OHCI_INTR_RHSC, &regs->intrdisable);
+		hcd->poll_rh = 1;
+		ohci->next_statechange = jiffies + STATECHANGE_DELAY;
+		ohci_writel (ohci, OHCI_INTR_RHSC, &regs->intrstatus);
+		usb_hcd_poll_rh_status(hcd);
+	}
 
 	if (ints & OHCI_INTR_UE) {
 		disable (ohci);

drivers/usb/host/ohci-hub.c

@@ -36,6 +36,14 @@
 
 /*-------------------------------------------------------------------------*/
 
+/* hcd->hub_irq_enable() */
+static void ohci_rhsc_enable (struct usb_hcd *hcd)
+{
+	struct ohci_hcd		*ohci = hcd_to_ohci (hcd);
+
+	ohci_writel (ohci, OHCI_INTR_RHSC, &ohci->regs->intrenable);
+}
+
 #ifdef	CONFIG_PM
 
 #define OHCI_SCHED_ENABLES \
@@ -123,6 +131,9 @@ static int ohci_bus_suspend (struct usb_hcd *hcd)
 	/* no resumes until devices finish suspending */
 	ohci->next_statechange = jiffies + msecs_to_jiffies (5);
 
+	/* no timer polling */
+	hcd->poll_rh = 0;
+
 done:
 	/* external suspend vs self autosuspend ... same effect */
 	if (status == 0)
@@ -256,8 +267,8 @@ static int ohci_bus_resume (struct usb_hcd *hcd)
 	/* TRSMRCY */
 	msleep (10);
 
-	/* keep it alive for ~5x suspend + resume costs */
-	ohci->next_statechange = jiffies + msecs_to_jiffies (250);
+	/* keep it alive for more than ~5x suspend + resume costs */
+	ohci->next_statechange = jiffies + STATECHANGE_DELAY;
 
 	/* maybe turn schedules back on */
 	enables = 0;
@@ -302,9 +313,10 @@ ohci_hub_status_data (struct usb_hcd *hcd, char *buf)
 {
 	struct ohci_hcd	*ohci = hcd_to_ohci (hcd);
 	int		i, changed = 0, length = 1;
-	int		can_suspend = device_may_wakeup(&hcd->self.root_hub->dev);
+	int		can_suspend;
 	unsigned long	flags;
 
+	can_suspend = device_may_wakeup(&hcd->self.root_hub->dev);
 	spin_lock_irqsave (&ohci->lock, flags);
 
 	/* handle autosuspended root:  finish resuming before
@@ -339,6 +351,10 @@ ohci_hub_status_data (struct usb_hcd *hcd, char *buf)
 	for (i = 0; i < ohci->num_ports; i++) {
 		u32	status = roothub_portstatus (ohci, i);
 
+		/* can't autosuspend with active ports */
+		if ((status & RH_PS_PES) && !(status & RH_PS_PSS))
+			can_suspend = 0;
+
 		if (status & (RH_PS_CSC | RH_PS_PESC | RH_PS_PSSC
 				| RH_PS_OCIC | RH_PS_PRSC)) {
 			changed = 1;
@@ -348,32 +364,41 @@ ohci_hub_status_data (struct usb_hcd *hcd, char *buf)
 			    buf [1] |= 1 << (i - 7);
 			continue;
 		}
+	}
 
-		/* can suspend if no ports are enabled; or if all all
-		 * enabled ports are suspended AND remote wakeup is on.
-		 */
-		if (!(status & RH_PS_CCS))
-			continue;
-		if ((status & RH_PS_PSS) && can_suspend)
-			continue;
+	/* after root hub changes, stop polling after debouncing
+	 * for a while and maybe kicking in autosuspend
+	 */
+	if (changed) {
+		ohci->next_statechange = jiffies + STATECHANGE_DELAY;
 		can_suspend = 0;
+	} else if (time_before (jiffies, ohci->next_statechange)) {
+		can_suspend = 0;
+	} else {
+#ifdef	CONFIG_PM
+		can_suspend = can_suspend
+			&& !ohci->ed_rm_list
+			&& ((OHCI_CTRL_HCFS | OHCI_SCHED_ENABLES)
+					& ohci->hc_control)
+				== OHCI_USB_OPER;
+#endif
+		if (hcd->uses_new_polling) {
+			hcd->poll_rh = 0;
+			/* use INTR_RHSC iff INTR_RD won't apply */
+			if (!can_suspend)
+				ohci_writel (ohci, OHCI_INTR_RHSC,
+						&ohci->regs->intrenable);
+		}
 	}
+
 done:
 	spin_unlock_irqrestore (&ohci->lock, flags);
 
-#ifdef CONFIG_PM
-	/* save power by suspending idle root hubs;
+#ifdef	CONFIG_PM
+	/* save power by autosuspending idle root hubs;
 	 * INTR_RD wakes us when there's work
 	 */
-	if (can_suspend
-			&& !changed
-			&& !ohci->ed_rm_list
-			&& ((OHCI_CTRL_HCFS | OHCI_SCHED_ENABLES)
-					& ohci->hc_control)
-				== OHCI_USB_OPER
-			&& time_after (jiffies, ohci->next_statechange)
-			&& usb_trylock_device (hcd->self.root_hub) == 0
-			) {
+	if (can_suspend && usb_trylock_device (hcd->self.root_hub) == 0) {
 		ohci_vdbg (ohci, "autosuspend\n");
 		(void) ohci_bus_suspend (hcd);
 		usb_unlock_device (hcd->self.root_hub);

drivers/usb/host/ohci-lh7a404.c

@@ -173,10 +173,6 @@ static const struct hc_driver ohci_lh7a404_hc_driver = {
 	 * basic lifecycle operations
 	 */
 	.start =		ohci_lh7a404_start,
-#ifdef	CONFIG_PM
-	/* suspend:		ohci_lh7a404_suspend,  -- tbd */
-	/* resume:		ohci_lh7a404_resume,   -- tbd */
-#endif /*CONFIG_PM*/
 	.stop =			ohci_stop,
 
 	/*
@@ -196,6 +192,7 @@ static const struct hc_driver ohci_lh7a404_hc_driver = {
 	 */
 	.hub_status_data =	ohci_hub_status_data,
 	.hub_control =		ohci_hub_control,
+	.hub_irq_enable =	ohci_rhsc_enable,
 #ifdef	CONFIG_PM
 	.bus_suspend =		ohci_bus_suspend,
 	.bus_resume =		ohci_bus_resume,

drivers/usb/host/ohci-omap.c

@@ -382,8 +382,10 @@ ohci_omap_start (struct usb_hcd *hcd)
 	int		ret;
 
 	config = hcd->self.controller->platform_data;
-	if (config->otg || config->rwc)
+	if (config->otg || config->rwc) {
+		ohci->hc_control = OHCI_CTRL_RWC;
 		writel(OHCI_CTRL_RWC, &ohci->regs->control);
+	}
 
 	if ((ret = ohci_run (ohci)) < 0) {
 		dev_err(hcd->self.controller, "can't start\n");
@@ -429,6 +431,7 @@ static const struct hc_driver ohci_omap_hc_driver = {
 	 */
 	.hub_status_data =	ohci_hub_status_data,
 	.hub_control =		ohci_hub_control,
+	.hub_irq_enable =	ohci_rhsc_enable,
 #ifdef	CONFIG_PM
 	.bus_suspend =		ohci_bus_suspend,
 	.bus_resume =		ohci_bus_resume,

drivers/usb/host/ohci-pci.c

@@ -176,11 +176,13 @@ static const struct hc_driver ohci_pci_hc_driver = {
 	 */
 	.reset =		ohci_pci_reset,
 	.start =		ohci_pci_start,
+	.stop =			ohci_stop,
+
 #ifdef	CONFIG_PM
+	/* these suspend/resume entries are for upstream PCI glue ONLY */
 	.suspend =		ohci_pci_suspend,
 	.resume =		ohci_pci_resume,
 #endif
-	.stop =			ohci_stop,
 
 	/*
 	 * managing i/o requests and associated device resources
@@ -199,6 +201,7 @@ static const struct hc_driver ohci_pci_hc_driver = {
 	 */
 	.hub_status_data =	ohci_hub_status_data,
 	.hub_control =		ohci_hub_control,
+	.hub_irq_enable =	ohci_rhsc_enable,
 #ifdef	CONFIG_PM
 	.bus_suspend =		ohci_bus_suspend,
 	.bus_resume =		ohci_bus_resume,

drivers/usb/host/ohci-ppc-soc.c

@@ -166,6 +166,7 @@ static const struct hc_driver ohci_ppc_soc_hc_driver = {
 	 */
 	.hub_status_data =	ohci_hub_status_data,
 	.hub_control =		ohci_hub_control,
+	.hub_irq_enable =	ohci_rhsc_enable,
 #ifdef	CONFIG_PM
 	.bus_suspend =		ohci_bus_suspend,
 	.bus_resume =		ohci_bus_resume,

drivers/usb/host/ohci-pxa27x.c

@@ -288,6 +288,7 @@ static const struct hc_driver ohci_pxa27x_hc_driver = {
 	 */
 	.hub_status_data =	ohci_hub_status_data,
 	.hub_control =		ohci_hub_control,
+	.hub_irq_enable =	ohci_rhsc_enable,
 #ifdef  CONFIG_PM
 	.bus_suspend =		ohci_bus_suspend,
 	.bus_resume =		ohci_bus_resume,

drivers/usb/host/ohci-s3c2410.c

@@ -465,6 +465,7 @@ static const struct hc_driver ohci_s3c2410_hc_driver = {
 	 */
 	.hub_status_data =	ohci_s3c2410_hub_status_data,
 	.hub_control =		ohci_s3c2410_hub_control,
+	.hub_irq_enable =	ohci_rhsc_enable,
 #ifdef	CONFIG_PM
 	.bus_suspend =		ohci_bus_suspend,
 	.bus_resume =		ohci_bus_resume,

drivers/usb/host/ohci-sa1111.c

@@ -212,10 +212,6 @@ static const struct hc_driver ohci_sa1111_hc_driver = {
 	 * basic lifecycle operations
 	 */
 	.start =		ohci_sa1111_start,
-#ifdef	CONFIG_PM
-	/* suspend:		ohci_sa1111_suspend,  -- tbd */
-	/* resume:		ohci_sa1111_resume,   -- tbd */
-#endif
 	.stop =			ohci_stop,
 
 	/*
@@ -235,6 +231,7 @@ static const struct hc_driver ohci_sa1111_hc_driver = {
 	 */
 	.hub_status_data =	ohci_hub_status_data,
 	.hub_control =		ohci_hub_control,
+	.hub_irq_enable =	ohci_rhsc_enable,
 #ifdef	CONFIG_PM
 	.bus_suspend =		ohci_bus_suspend,
 	.bus_resume =		ohci_bus_resume,