Skip site navigation (1)Skip section navigation (2) 
Date:      Tue, 28 Jul 2015 07:30:08 +0000 (UTC)
From:      Hans Petter Selasky <hselasky@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r285935 - head/sys/dev/usb/controller
Message-ID:  <201507280730.t6S7U8eS069698@repo.freebsd.org>
next in thread | raw e-mail | index | archive | help 
Author: hselasky
Date: Tue Jul 28 07:30:07 2015
New Revision: 285935
URL: https://svnweb.freebsd.org/changeset/base/285935

Log:
  Optimise the DWC OTG host mode driver's receive path:
  
  Remove NAKing limit and pause IN and OUT transactions for 125us in
  case of NAK response for BULK and CONTROL endpoints. This gets the
  receive latency down and improves USB network throughput at the cost
  of some CPU usage.
  
  MFC after:	1 month

Modified:
  head/sys/dev/usb/controller/dwc_otg.c
  head/sys/dev/usb/controller/dwc_otg.h

Modified: head/sys/dev/usb/controller/dwc_otg.c
==============================================================================
--- head/sys/dev/usb/controller/dwc_otg.c	Tue Jul 28 07:04:51 2015	(r285934)
+++ head/sys/dev/usb/controller/dwc_otg.c	Tue Jul 28 07:30:07 2015	(r285935)
@@ -453,8 +453,12 @@ static void
 dwc_otg_enable_sof_irq(struct dwc_otg_softc *sc)
 {
 	/* In device mode we don't use the SOF interrupt */
-	if (sc->sc_flags.status_device_mode != 0 ||
-	    (sc->sc_irq_mask & GINTMSK_SOFMSK) != 0)
+	if (sc->sc_flags.status_device_mode != 0)
+		return;
+	/* Ensure the SOF interrupt is not disabled */
+	sc->sc_needsof = 1;
+	/* Check if the SOF interrupt is already enabled */
+	if ((sc->sc_irq_mask & GINTMSK_SOFMSK) != 0)
 		return;
 	sc->sc_irq_mask |= GINTMSK_SOFMSK;
 	DWC_OTG_WRITE_4(sc, DOTG_GINTMSK, sc->sc_irq_mask);
@@ -775,7 +779,7 @@ check_state:
 
 	case DWC_CHAN_ST_WAIT_ANE:
 		if (hcint & (HCINT_RETRY | HCINT_ERRORS)) {
-			td->did_nak++;
+			td->did_nak = 1;
 			td->tt_scheduled = 0;
 			goto send_pkt;
 		} else if (hcint & (HCINT_ACK | HCINT_NYET)) {
@@ -789,7 +793,7 @@ check_state:
 
 	case DWC_CHAN_ST_WAIT_S_ANE:
 		if (hcint & (HCINT_RETRY | HCINT_ERRORS)) {
-			td->did_nak++;
+			td->did_nak = 1;
 			td->tt_scheduled = 0;
 			goto send_pkt;
 		} else if (hcint & (HCINT_ACK | HCINT_NYET)) {
@@ -801,7 +805,7 @@ check_state:
 		if (hcint & HCINT_NYET) {
 			goto send_cpkt;
 		} else if (hcint & (HCINT_RETRY | HCINT_ERRORS)) {
-			td->did_nak++;
+			td->did_nak = 1;
 			td->tt_scheduled = 0;
 			goto send_pkt;
 		} else if (hcint & HCINT_ACK) {
@@ -1069,8 +1073,17 @@ dwc_otg_host_rate_check(struct dwc_otg_s
 		if (!td->tt_scheduled)
 			goto busy;
 		td->tt_scheduled = 0;
-	} else if (td->did_nak >= DWC_OTG_NAK_MAX) {
-		goto busy;
+	} else if (td->did_nak != 0) {
+		uint8_t frame_num = (uint8_t)sc->sc_last_frame_num;
+		/* check if we should pause sending queries for 125us */
+		if (td->tmr_res == frame_num) {
+			/* wait a bit */
+			dwc_otg_enable_sof_irq(sc);
+			goto busy;
+		}
+		/* query for data one more time */
+		td->tmr_res = frame_num;
+		td->did_nak = 0;
 	} else if (td->set_toggle) {
 		td->set_toggle = 0;
 		td->toggle = 1;
@@ -1257,7 +1270,7 @@ dwc_otg_host_data_rx(struct dwc_otg_soft
 					goto receive_pkt;
 				}
 			}
-			td->did_nak++;
+			td->did_nak = 1;
 			td->tt_scheduled = 0;
 			if (td->hcsplt != 0)
 				goto receive_spkt;
@@ -1312,7 +1325,7 @@ dwc_otg_host_data_rx(struct dwc_otg_soft
 		 * case of interrupt and isochronous transfers:
 		 */ 
 		if (hcint & (HCINT_RETRY | HCINT_ERRORS)) {
-			td->did_nak++;
+			td->did_nak = 1;
 			td->tt_scheduled = 0;
 			goto receive_spkt;
 		} else if (hcint & HCINT_NYET) {
@@ -1638,7 +1651,7 @@ dwc_otg_host_data_tx(struct dwc_otg_soft
 
 	case DWC_CHAN_ST_WAIT_ANE:
 		if (hcint & (HCINT_RETRY | HCINT_ERRORS)) {
-			td->did_nak++;
+			td->did_nak = 1;
 			td->tt_scheduled = 0;
 			goto send_pkt;
 		} else if (hcint & (HCINT_ACK | HCINT_NYET)) {
@@ -1664,7 +1677,7 @@ dwc_otg_host_data_tx(struct dwc_otg_soft
 
 	case DWC_CHAN_ST_WAIT_S_ANE:
 		if (hcint & (HCINT_RETRY | HCINT_ERRORS)) {
-			td->did_nak++;
+			td->did_nak = 1;
 			td->tt_scheduled = 0;
 			goto send_pkt;
 		} else if (hcint & (HCINT_ACK | HCINT_NYET)) {
@@ -1677,7 +1690,7 @@ dwc_otg_host_data_tx(struct dwc_otg_soft
 		if (hcint & HCINT_NYET) {
 			goto send_cpkt;
 		} else if (hcint & (HCINT_RETRY | HCINT_ERRORS)) {
-			td->did_nak++;
+			td->did_nak = 1;
 			td->tt_scheduled = 0;
 			goto send_pkt;
 		} else if (hcint & HCINT_ACK) {
@@ -2280,8 +2293,6 @@ static void
 dwc_otg_timer(void *_sc)
 {
 	struct dwc_otg_softc *sc = _sc;
-	struct usb_xfer *xfer;
-	struct dwc_otg_td *td;
 
 	USB_BUS_LOCK_ASSERT(&sc->sc_bus, MA_OWNED);
 
@@ -2292,14 +2303,6 @@ dwc_otg_timer(void *_sc)
 	/* increment timer value */
 	sc->sc_tmr_val++;
 
-	TAILQ_FOREACH(xfer, &sc->sc_bus.intr_q.head, wait_entry) {
-		td = xfer->td_transfer_cache;
-		if (td != NULL) {
-			/* reset NAK counter */ 
-			td->did_nak = 0;
-		}
-	}
-
 	/* enable SOF interrupt, which will poll jobs */
 	dwc_otg_enable_sof_irq(sc);
 
@@ -2459,8 +2462,7 @@ dwc_otg_update_host_transfer_schedule_lo
 		TAILQ_FOREACH_SAFE(xfer, &sc->sc_bus.intr_q.head, wait_entry, xfer_next) {
 			td = xfer->td_transfer_cache;
 			if (td == NULL ||
-			    td->ep_type != UE_CONTROL ||
-			    td->did_nak >= DWC_OTG_NAK_MAX) {
+			    td->ep_type != UE_CONTROL) {
 				continue;
 			}
 
@@ -2480,8 +2482,7 @@ dwc_otg_update_host_transfer_schedule_lo
 		TAILQ_FOREACH_SAFE(xfer, &sc->sc_bus.intr_q.head, wait_entry, xfer_next) {
 			td = xfer->td_transfer_cache;
 			if (td == NULL ||
-			    td->ep_type != UE_BULK ||
-			    td->did_nak >= DWC_OTG_NAK_MAX) {
+			    td->ep_type != UE_BULK) {
 				continue;
 			}
 
@@ -3244,7 +3245,7 @@ dwc_otg_setup_standard_chain(struct usb_
 				td->tmr_res = 1;
 			} else {
 				td->tmr_val = 0;
-				td->tmr_res = 0;
+				td->tmr_res = (uint8_t)sc->sc_last_frame_num;
 			}
 			break;
 		case USB_SPEED_HIGH:
@@ -3269,7 +3270,7 @@ dwc_otg_setup_standard_chain(struct usb_
 				td->tmr_res = 1 << usbd_xfer_get_fps_shift(xfer);
 			} else {
 				td->tmr_val = 0;
-				td->tmr_res = 0;
+				td->tmr_res = (uint8_t)sc->sc_last_frame_num;
 			}
 			break;
 		default:
@@ -3309,8 +3310,6 @@ static void
 dwc_otg_start_standard_chain(struct usb_xfer *xfer)
 {
 	struct dwc_otg_softc *sc = DWC_OTG_BUS2SC(xfer->xroot->bus);
-	struct usb_xfer_root *xroot;
-	struct dwc_otg_td *td;
 
 	DPRINTFN(9, "\n");
 
@@ -3341,24 +3340,6 @@ dwc_otg_start_standard_chain(struct usb_
 
 	/* enable SOF interrupt, if any */
 	dwc_otg_enable_sof_irq(sc);
-
-	td = xfer->td_transfer_cache;
-	if (td->ep_type != UE_BULK)
-		goto done;
-
-	xroot = xfer->xroot;
-
-	/*
-	 * Optimise the ping-pong effect by waking up other BULK
-	 * transfers belonging to the same device group:
-	 */
-	TAILQ_FOREACH(xfer, &sc->sc_bus.intr_q.head, wait_entry) {
-		td = xfer->td_transfer_cache;
-		if (td == NULL || td->ep_type != UE_BULK || xfer->xroot != xroot)
-			continue;
-		/* reset NAK counter */ 
-		td->did_nak = 0;
-	}
 done:
 	USB_BUS_SPIN_UNLOCK(&sc->sc_bus);
 }

Modified: head/sys/dev/usb/controller/dwc_otg.h
==============================================================================
--- head/sys/dev/usb/controller/dwc_otg.h	Tue Jul 28 07:04:51 2015	(r285934)
+++ head/sys/dev/usb/controller/dwc_otg.h	Tue Jul 28 07:30:07 2015	(r285935)
@@ -37,7 +37,6 @@
 #define	DWC_OTG_TT_SLOT_MAX 8
 #define	DWC_OTG_SLOT_IDLE_MAX 3
 #define	DWC_OTG_SLOT_IDLE_MIN 2
-#define	DWC_OTG_NAK_MAX 16	/* 16 NAKs = 2 ms */
 #ifndef DWC_OTG_TX_MAX_FIFO_SIZE
 #define	DWC_OTG_TX_MAX_FIFO_SIZE DWC_OTG_MAX_TXN
 #endif
@@ -68,7 +67,6 @@ struct dwc_otg_td {
 	uint8_t errcnt;
 	uint8_t tmr_res;
 	uint8_t tmr_val;
-	uint8_t did_nak;		/* NAK counter */
 	uint8_t	ep_no;
 	uint8_t ep_type;
 	uint8_t channel;
@@ -93,6 +91,7 @@ struct dwc_otg_td {
 	uint8_t set_toggle:1;
 	uint8_t got_short:1;
 	uint8_t tt_scheduled:1;
+	uint8_t did_nak:1;
 };
 
 struct dwc_otg_tt_info {

Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?201507280730.t6S7U8eS069698>