musb_hdrc: host vbus and connect/disconnect fixes

Teach host side VBUS powerup and connect logic about the problem whereby
the HDRC core wrongly reports VBUS_ERROR during initial powerup.

Remove previous non-working workaround for tusb powering VBUS:  don't
try handling CPEN by hand.

Rest of the fix for disconnection issues in A_SUSPEND.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>

drivers/usb/musb/musbdefs.h

@@ -415,6 +415,7 @@ struct musb {
 	struct musb_hw_ep	 aLocalEnd[MUSB_C_NUM_EPS];
 #define control_ep		aLocalEnd
 
+#define VBUSERR_RETRY_COUNT	3
 	u16			vbuserr_retry;
 	u16 wEndMask;
 	u8 bEndCount;

drivers/usb/musb/plat_uds.c

@@ -108,9 +108,6 @@
 #endif
 
 #include "musbdefs.h"
-// #ifdef CONFIG_USB_MUSB_HDRC_HCD
-#define VBUSERR_RETRY_COUNT	2		/* is this too few? */
-// #endif
 
 
 #ifdef CONFIG_ARCH_DAVINCI
@@ -411,8 +408,52 @@ static irqreturn_t musb_stage0_irq(struct musb * pThis, u8 bIntrUSB,
 	}
 
 	if (bIntrUSB & MGC_M_INTR_VBUSERROR) {
+		int	ignore = 0;
+
+		/* During connection as an A-Device, we may see a short
+		 * current spikes causing voltage drop, because of cable
+		 * and peripheral capacitance combined with vbus draw.
+		 * (So: less common with truly self-powered devices, where
+		 * vbus doesn't act like a power supply.)
+		 *
+		 * Such spikes are short; usually less than ~500 usec, max
+		 * of ~2 msec.  That is, they're not sustained overcurrent
+		 * errors, though they're reported using VBUSERROR irqs.
+		 *
+		 * Workarounds:  (a) hardware: use self powered devices.
+		 * (b) software:  ignore non-repeated VBUS errors.
+		 *
+		 * REVISIT:  do delays from lots of DEBUG_KERNEL checks
+		 * make trouble here, keeping VBUS < 4.4V ?
+		 */
+		switch (pThis->xceiv.state) {
+		case OTG_STATE_A_HOST:
+			/* recovery is dicey once we've gotten past the
+			 * initial stages of enumeration, but if VBUS
+			 * stayed ok at the other end of the link, and
+			 * another reset is due (at least for high speed,
+			 * to redo the chirp etc), it might work OK...
+			 */
+		case OTG_STATE_A_WAIT_BCON:
+		case OTG_STATE_A_WAIT_VRISE:
+			if (pThis->vbuserr_retry) {
+				pThis->vbuserr_retry--;
+				ignore = 1;
+				devctl |= MGC_M_DEVCTL_SESSION;
+				musb_writeb(pBase, MGC_O_HDRC_DEVCTL, devctl);
+			} else {
+				pThis->port1_status |=
+					  (1 << USB_PORT_FEAT_OVER_CURRENT)
+					| (1 << USB_PORT_FEAT_C_OVER_CURRENT);
+			}
+			break;
+		default:
+			break;
+		}
 
-		DBG(1, "VBUS_ERROR (%02x, %s), retry #%d\n", devctl,
+		DBG(1, "VBUS_ERROR in %s (%02x, %s), retry #%d, port1 %08x\n",
+				otg_state_string(pThis),
+				devctl,
 				({ char *s;
 				switch (devctl & MGC_M_DEVCTL_VBUS) {
 				case 0 << MGC_S_DEVCTL_VBUS:
@@ -425,13 +466,14 @@ static irqreturn_t musb_stage0_irq(struct musb * pThis, u8 bIntrUSB,
 				default:
 					s = "VALID"; break;
 				}; s; }),
-				pThis->vbuserr_retry);
+				VBUSERR_RETRY_COUNT - pThis->vbuserr_retry,
+				pThis->port1_status);
 
 		/* go through A_WAIT_VFALL then start a new session */
-		musb_set_vbus(pThis, 0);
+		if (!ignore)
+			musb_set_vbus(pThis, 0);
 		handled = IRQ_HANDLED;
-	} else
-		pThis->vbuserr_retry = VBUSERR_RETRY_COUNT;
+	}
 
 	if (bIntrUSB & MGC_M_INTR_CONNECT) {
 		handled = IRQ_HANDLED;
@@ -468,10 +510,13 @@ static irqreturn_t musb_stage0_irq(struct musb * pThis, u8 bIntrUSB,
 			pThis->xceiv.state = OTG_STATE_B_HOST;
 			break;
 		default:
-			pThis->xceiv.state = OTG_STATE_A_HOST;
+			if ((devctl & MGC_M_DEVCTL_VBUS)
+					== (3 << MGC_S_DEVCTL_VBUS))
+				pThis->xceiv.state = OTG_STATE_A_HOST;
 			break;
 		}
-		DBG(1, "CONNECT (%s)\n", otg_state_string(pThis));
+		DBG(1, "CONNECT (%s) devctl %02x\n",
+				otg_state_string(pThis), devctl);
 	}
 #endif	/* CONFIG_USB_MUSB_HDRC_HCD */
 
@@ -566,18 +611,35 @@ static irqreturn_t musb_stage2_irq(struct musb * pThis, u8 bIntrUSB,
 #endif
 
 	if ((bIntrUSB & MGC_M_INTR_DISCONNECT) && !pThis->bIgnoreDisconnect) {
-		DBG(1, "DISCONNECT as %s, devctl %02x\n",
+		DBG(1, "DISCONNECT (%s) as %s, devctl %02x\n",
+				otg_state_string(pThis),
 				MUSB_MODE(pThis), devctl);
 		handled = IRQ_HANDLED;
-		pThis->is_active = 0;
 
-		/* need to check it against pThis, because devctl is going
-		 * to report ID low as soon as the device gets disconnected
-		 */
-		if (is_host_active(pThis))
+		switch (pThis->xceiv.state) {
+#ifdef CONFIG_USB_MUSB_HDRC_HCD
+		case OTG_STATE_A_HOST:
+		case OTG_STATE_A_SUSPEND:
 			musb_root_disconnect(pThis);
-		else
+			break;
+#endif	/* HOST */
+#ifdef CONFIG_USB_MUSB_OTG
+		case OTG_STATE_A_PERIPHERAL:
+		case OTG_STATE_B_HOST:
+			musb_root_disconnect(pThis);
+			/* FALLTHROUGH */
+		case OTG_STATE_B_WAIT_ACON:
+#endif	/* OTG */
+#ifdef CONFIG_USB_GADGET_MUSB_HDRC
+		case OTG_STATE_B_PERIPHERAL:
 			musb_g_disconnect(pThis);
+			break;
+#endif	/* GADGET */
+		default:
+			WARN("unhandled DISCONNECT transition (%s)\n",
+				otg_state_string(pThis));
+			break;
+		}
 
 		schedule_work(&pThis->irq_work);
 	}
@@ -1299,8 +1361,6 @@ irqreturn_t musb_interrupt(struct musb *musb)
 	if (musb->int_usb & STAGE0_MASK)
 		retval |= musb_stage0_irq(musb, musb->int_usb,
 				devctl, power);
-	else
-		musb->vbuserr_retry = VBUSERR_RETRY_COUNT;
 
 	/* "stage 1" is handling endpoint irqs */
 
@@ -1450,7 +1510,7 @@ musb_cable_show(struct device *dev, struct device_attribute *attr, char *buf)
 	int vbus;
 
 	spin_lock_irqsave(&musb->Lock, flags);
-#ifdef CONFIG_USB_TUSB6010
+#if defined(CONFIG_USB_TUSB6010) && !defined(CONFIG_USB_MUSB_OTG)
 	/* REVISIT: connect-A != connect-B ... */
 	vbus = musb_platform_get_vbus_status(musb);
 	if (vbus)

drivers/usb/musb/tusb6010.c

@@ -336,7 +336,10 @@ static void tusb_set_vbus(struct musb *musb, int is_on)
 	u32		conf, prcm, timer;
 	u8		devctl;
 
-	/* we control CPEN in software not hardware ... */
+	/* HDRC controls CPEN, but beware current surges during device
+	 * connect.  They can trigger transient overcurrent conditions
+	 * that must be ignored.
+	 */
 
 	prcm = musb_readl(base, TUSB_PRCM_MNGMT);
 	conf = musb_readl(base, TUSB_DEV_CONF);
@@ -344,25 +347,28 @@ static void tusb_set_vbus(struct musb *musb, int is_on)
 
 	if (is_on) {
 		musb->is_active = 1;
-		prcm |= TUSB_PRCM_MNGMT_5V_CPEN;
 		timer = OTG_TIMER_MS(OTG_TIME_A_WAIT_VRISE);
 
 		musb->xceiv.default_a = 1;
 		musb->xceiv.state = OTG_STATE_A_WAIT_VRISE;
+		devctl |= MGC_M_DEVCTL_SESSION;
 
 		conf |= TUSB_DEV_CONF_USB_HOST_MODE;
-
+		MUSB_HST_MODE(musb);
 	} else {
-		prcm &= ~TUSB_PRCM_MNGMT_5V_CPEN;
+		musb->is_active = 0;
 		timer = 0;
 
-		if (musb->xceiv.default_a) {
-			musb->xceiv.state = OTG_STATE_A_WAIT_VFALL;
-			devctl &= ~MGC_M_DEVCTL_SESSION;
-		} else {
-			musb->xceiv.state = OTG_STATE_B_IDLE;
-			musb->is_active = 0;
-		}
+		/* NOTE:  we're skipping A_WAIT_VFALL -> A_IDLE and
+		 * jumping right to B_IDLE...
+		 */
+
+		musb->xceiv.default_a = 0;
+		musb->xceiv.state = OTG_STATE_B_IDLE;
+		devctl &= ~MGC_M_DEVCTL_SESSION;
+
+		conf &= ~TUSB_DEV_CONF_USB_HOST_MODE;
+		MUSB_DEV_MODE(musb);
 	}
 	prcm &= ~(TUSB_PRCM_MNGMT_15_SW_EN | TUSB_PRCM_MNGMT_33_SW_EN);
 
@@ -402,6 +408,16 @@ tusb_otg_ints(struct musb *musb, u32 int_src, void __iomem *base)
 		/* B-dev state machine:  no vbus ~= disconnect */
 		if ((is_otg_enabled(musb) && !musb->xceiv.default_a)
 				|| !is_host_enabled(musb)) {
+#ifdef CONFIG_USB_MUSB_HDRC_HCD
+			// ? musb_root_disconnect(musb);
+			musb->port1_status &=
+				~(USB_PORT_STAT_CONNECTION
+				| USB_PORT_STAT_ENABLE
+				| USB_PORT_STAT_LOW_SPEED
+				| USB_PORT_STAT_HIGH_SPEED
+				| USB_PORT_STAT_TEST
+				);
+#endif
 
 			if (otg_stat & TUSB_DEV_OTG_STAT_SESS_END) {
 				if (musb->xceiv.state != OTG_STATE_B_IDLE) {
@@ -426,9 +442,8 @@ tusb_otg_ints(struct musb *musb, u32 int_src, void __iomem *base)
 				 */
 				break;
 			case OTG_STATE_A_WAIT_VFALL:
-				/* REVISIT this irq triggers at too high a
-				 * voltage ... we probably need to use the
-				 * OTG timer to wait for session end.
+				/* REVISIT this irq triggers during short
+				 * spikes causet by enumeration ...
 				 */
 				if (musb->vbuserr_retry) {
 					musb->vbuserr_retry--;
@@ -449,30 +464,32 @@ tusb_otg_ints(struct musb *musb, u32 int_src, void __iomem *base)
 
 		switch (musb->xceiv.state) {
 		case OTG_STATE_A_WAIT_VRISE:
-			/* VBUS has probably been valid for a while now */
+			/* VBUS has probably been valid for a while now,
+			 * but may well have bounced out of range a bit
+			 */
 			devctl = musb_readb(musb->pRegs, MGC_O_HDRC_DEVCTL);
 			if (otg_stat & TUSB_DEV_OTG_STAT_VBUS_VALID) {
+				u32	timer;
+
 				if ((devctl & MGC_M_DEVCTL_VBUS)
 						!= MGC_M_DEVCTL_VBUS) {
 					DBG(2, "devctl %02x\n", devctl);
 					break;
 				}
+				musb->xceiv.state = OTG_STATE_A_WAIT_BCON;
 
-				/* request a session, then DEVCTL_HM will
-				 * be set by the controller
+				/* REVISIT: if nothing is connected yet,
+				 * mark controller as inactive so that
+				 * we can suspend the TUSB chip.
 				 */
-				devctl |= MGC_M_DEVCTL_SESSION;
-				musb_writeb(musb->pRegs, MGC_O_HDRC_DEVCTL,
-						devctl);
-				musb->xceiv.state = OTG_STATE_A_WAIT_BCON;
 
 				/* timeout 0 == infinite (like non-OTG hosts) */
-				if (OTG_TIME_A_WAIT_BCON)
+				timer = OTG_TIMER_MS(OTG_TIME_A_WAIT_BCON);
+				if (timer)
 					musb_writel(base, TUSB_DEV_OTG_TIMER,
-						OTG_TIMER_MS(OTG_TIME_A_WAIT_BCON));
-				else
-					musb_writel(base, TUSB_DEV_OTG_TIMER, 0);
+							timer);
 			} else {
+				/* REVISIT report overcurrent to hub? */
 				ERR("vbus too slow, devctl %02x\n", devctl);
 				tusb_set_vbus(musb, 0);
 			}
@@ -488,7 +505,6 @@ tusb_otg_ints(struct musb *musb, u32 int_src, void __iomem *base)
 		default:
 			break;
 		}
-		musb_writel(base, TUSB_DEV_OTG_TIMER, 0);
 	}
 }
 
@@ -747,8 +763,7 @@ static int __devinit tusb_start(struct musb *musb)
 	musb_writel(base, TUSB_VLYNQ_CTRL, 8);
 
 	/* Select PHY free running 60MHz as a system clock */
-	musb_writel(base, TUSB_PRCM_CONF, //FIXME: CPEN should not be needed!
-			TUSB_PRCM_CONF_SFW_CPEN | TUSB_PRCM_CONF_SYS_CLKSEL(1));
+	tusb_set_clock_source(musb, 1);
 
 	/* VBus valid timer 1us, disable DFT/Debug and VLYNQ clocks for
 	 * power saving, enable VBus detect and session end comparators,

drivers/usb/musb/virthub.c

@@ -144,6 +144,7 @@ static void musb_port_reset(struct musb *musb, u8 bReset)
 					| (USB_PORT_STAT_C_ENABLE << 16);
 		usb_hcd_poll_rh_status(musb_to_hcd(musb));
 
+		musb->vbuserr_retry = VBUSERR_RETRY_COUNT;
 	}
 }