[PATCH] ehci-hcd (1/2): portability (2.4), tasklet,

This should be innocuous; I expect most folk won't notice anything
better (or worse) from this patch unless they're using Intel EHCI.

removing tasklet
     - parts of davem's patch (passing pt_regs down)
     - remove 'max_completions'
     - update cleanup after hc died
     - fix an urb unlink oops (null ptr) that happens more often this way

talking to hardware
     - fixes for some short read issues (may still be others)
	* use qtd->hw_alt_next to stop qh processing after short reads
	* detect/report short reads differently
     - longer reset timeout (it was excessively short, broke Intel)

other
     - simpler diagnostics portability to 2.4:  wrap dev_err() etc
     - urb unlink wait and non-wait unlink codepaths share most code
     - don't try ehci_stop() in interrupt context (bug from hcd layer)
     - minor stuff, including
	* some "after hc died" paths were wrong
	* verbose debug messages compile again
	* don't break error irq count

drivers/usb/host/ehci-dbg.c

@@ -18,21 +18,45 @@
 
 /* this file is part of ehci-hcd.c */
 
+#if LINUX_VERSION_CODE > KERNEL_VERSION(2,5,50)
+
 #define ehci_dbg(ehci, fmt, args...) \
 	dev_dbg (*(ehci)->hcd.controller, fmt, ## args )
+#define ehci_err(ehci, fmt, args...) \
+	dev_err (*(ehci)->hcd.controller, fmt, ## args )
+#define ehci_info(ehci, fmt, args...) \
+	dev_info (*(ehci)->hcd.controller, fmt, ## args )
+#define ehci_warn(ehci, fmt, args...) \
+	dev_warn (*(ehci)->hcd.controller, fmt, ## args )
 
-#ifdef EHCI_VERBOSE_DEBUG
-#define ehci_vdbg(ehci, fmt, args...) \
-	dev_dbg (*(ehci)->hcd.controller, fmt, ## args )
 #else
-#define ehci_vdbg(ehci, fmt, args...) do { } while (0)
+
+#ifdef DEBUG
+#define ehci_dbg(ehci, fmt, args...) \
+	printk(KERN_DEBUG "%s %s: " fmt, hcd_name, \
+		(ehci)->hcd.pdev->slot_name, ## args )
+#else
+#define ehci_dbg(ehci, fmt, args...) do { } while (0)
+#endif
+
+#define ehci_err(ehci, fmt, args...) \
+	printk(KERN_ERR "%s %s: " fmt, hcd_name, \
+		(ehci)->hcd.pdev->slot_name, ## args )
+#define ehci_info(ehci, fmt, args...) \
+	printk(KERN_INFO "%s %s: " fmt, hcd_name, \
+		(ehci)->hcd.pdev->slot_name, ## args )
+#define ehci_warn(ehci, fmt, args...) \
+	printk(KERN_WARNING "%s %s: " fmt, hcd_name, \
+		(ehci)->hcd.pdev->slot_name, ## args )
 #endif
 
 
 #ifdef EHCI_VERBOSE_DEBUG
 #	define vdbg dbg
+#	define ehci_vdbg ehci_dbg
 #else
-	static inline void vdbg (char *fmt, ...) { }
+#	define vdbg(fmt,args...) do { } while (0)
+#	define ehci_vdbg(ehci, fmt, args...) do { } while (0)
 #endif
 
 #ifdef	DEBUG
@@ -289,7 +313,8 @@ static void qh_lines (struct ehci_qh *qh, char **nextp, unsigned *sizep)
 
 	scratch = cpu_to_le32p (&qh->hw_info1);
 	hw_curr = cpu_to_le32p (&qh->hw_current);
-	temp = snprintf (next, size, "qh/%p dev%d %cs ep%d %08x %08x (%08x %08x)",
+	temp = snprintf (next, size,
+			"qh/%p dev%d %cs ep%d %08x %08x (%08x %08x)",
 			qh, scratch & 0x007f,
 			speed_char (scratch),
 			(scratch >> 8) & 0x000f,

drivers/usb/host/ehci-hcd.c

@@ -123,12 +123,6 @@ static int log2_irq_thresh = 0;		// 0 to 6
 MODULE_PARM (log2_irq_thresh, "i");
 MODULE_PARM_DESC (log2_irq_thresh, "log2 IRQ latency, 1-64 microframes");
 
-/* allow irqs at least every N URB completions */
-static int max_completions = 16;
-MODULE_PARM (max_completions, "i");
-MODULE_PARM_DESC (max_completions,
-		"limit for urb completions called with irqs disenabled");
-
 #define	INTR_MASK (STS_IAA | STS_FATAL | STS_ERR | STS_INT)
 
 /*-------------------------------------------------------------------------*/
@@ -202,7 +196,7 @@ static int ehci_reset (struct ehci_hcd *ehci)
 	dbg_cmd (ehci, "reset", command);
 	writel (command, &ehci->regs->command);
 	ehci->hcd.state = USB_STATE_HALT;
-	return handshake (&ehci->regs->command, CMD_RESET, 0, 250);
+	return handshake (&ehci->regs->command, CMD_RESET, 0, 250 * 1000);
 }
 
 /* idle the controller (from running) */
@@ -289,8 +283,7 @@ static int bios_handoff (struct ehci_hcd *ehci, int where, u32 cap)
 			pci_read_config_dword (ehci->hcd.pdev, where, &cap);
 		} while ((cap & (1 << 16)) && msec);
 		if (cap & (1 << 16)) {
-			dev_info (*ehci->hcd.controller,
-				"BIOS handoff failed (%d, %04x)\n",
+			ehci_err (ehci, "BIOS handoff failed (%d, %04x)\n",
 				where, cap);
 			return 1;
 		} 
@@ -333,8 +326,7 @@ static int ehci_start (struct usb_hcd *hcd)
 				return -EOPNOTSUPP;
 			break;
 		case 0:			/* illegal reserved capability */
-			dev_warn (*ehci->hcd.controller,
-					"illegal capability!\n");
+			ehci_warn (ehci, "illegal capability!\n");
 			cap = 0;
 			/* FALLTHROUGH */
 		default:		/* unknown */
@@ -381,6 +373,8 @@ static int ehci_start (struct usb_hcd *hcd)
 	 * dedicate a qh for the async ring head, since we couldn't unlink
 	 * a 'real' qh without stopping the async schedule [4.8].  use it
 	 * as the 'reclamation list head' too.
+	 * its dummy is used in hw_alt_next of many tds, to prevent the qh
+	 * from automatically advancing to the next td after short reads.
 	 */
 	ehci->async->qh_next.qh = 0;
 	ehci->async->hw_next = QH_NEXT (ehci->async->qh_dma);
@@ -388,8 +382,7 @@ static int ehci_start (struct usb_hcd *hcd)
 	ehci->async->hw_token = cpu_to_le32 (QTD_STS_HALT);
 	ehci->async->hw_qtd_next = EHCI_LIST_END;
 	ehci->async->qh_state = QH_STATE_LINKED;
-	ehci_qtd_free (ehci, ehci->async->dummy);
-	ehci->async->dummy = 0;
+	ehci->async->hw_alt_next = QTD_NEXT (ehci->async->dummy->qtd_dma);
 	writel ((u32)ehci->async->qh_dma, &ehci->regs->async_next);
 
 	/*
@@ -406,8 +399,7 @@ static int ehci_start (struct usb_hcd *hcd)
 	if (HCC_64BIT_ADDR (hcc_params)) {
 		writel (0, &ehci->regs->segment);
 		if (!pci_set_dma_mask (ehci->hcd.pdev, 0xffffffffffffffffULL))
-			dev_info (*ehci->hcd.controller,
-				"enabled 64bit PCI DMA (DAC)\n");
+			ehci_info (ehci, "enabled 64bit PCI DMA\n");
 	}
 
 	/* clear interrupt enables, set irq latency */
@@ -454,7 +446,7 @@ static int ehci_start (struct usb_hcd *hcd)
         /* PCI Serial Bus Release Number is at 0x60 offset */
 	pci_read_config_byte (hcd->pdev, 0x60, &tempbyte);
 	temp = readw (&ehci->caps->hci_version);
-	dev_info (*hcd->controller,
+	ehci_info (ehci,
 		"USB %x.%x enabled, EHCI %x.%02x, driver %s\n",
 		((tempbyte & 0xf0)>>4), (tempbyte & 0x0f),
 		temp >> 8, temp & 0xff, DRIVER_VERSION);
@@ -494,9 +486,10 @@ static void ehci_stop (struct usb_hcd *hcd)
 	/* no more interrupts ... */
 	if (hcd->state == USB_STATE_RUNNING)
 		ehci_ready (ehci);
-	if (in_interrupt ())		/* should not happen!! */
-		dev_err (*hcd->controller, "stopped %s!\n", RUN_CONTEXT);
-	else
+	if (in_interrupt ()) {		/* must not happen!! */
+		ehci_err (ehci, "stopped in_interrupt!\n");
+		return;
+	}
 	del_timer_sync (&ehci->watchdog);
 	ehci_reset (ehci);
 
@@ -621,14 +614,15 @@ dbg ("%s: resume port %d", hcd_to_bus (hcd)->bus_name, i);
 static void ehci_tasklet (unsigned long param)
 {
 	struct ehci_hcd		*ehci = (struct ehci_hcd *) param;
+	struct pt_regs		*regs = NULL;
 
 	spin_lock_irq (&ehci->lock);
 
 	if (ehci->reclaim_ready)
-		end_unlink_async (ehci);
-	scan_async (ehci);
+		end_unlink_async (ehci, regs);
+	scan_async (ehci, regs);
 	if (ehci->next_uframe != -1)
-		scan_periodic (ehci);
+		scan_periodic (ehci, regs);
 
 	spin_unlock_irq (&ehci->lock);
 }
@@ -643,7 +637,7 @@ static void ehci_irq (struct usb_hcd *hcd, struct pt_regs *regs)
 
 	/* e.g. cardbus physical eject */
 	if (status == ~(u32) 0) {
-		dbg ("%s: device removed!", hcd_to_bus (hcd)->bus_name);
+		ehci_dbg (ehci, "device removed\n");
 		goto dead;
 	}
 
@@ -681,8 +675,7 @@ static void ehci_irq (struct usb_hcd *hcd, struct pt_regs *regs)
 
 	/* PCI errors [4.15.2.4] */
 	if (unlikely ((status & STS_FATAL) != 0)) {
-		err ("%s: fatal error, state %x",
-			hcd_to_bus (hcd)->bus_name, hcd->state);
+		ehci_err (ehci, "fatal error\n");
 dead:
 		ehci_reset (ehci);
 		/* generic layer kills/unlinks all urbs, then
@@ -754,52 +747,52 @@ static int ehci_urb_enqueue (
 static int ehci_urb_dequeue (struct usb_hcd *hcd, struct urb *urb)
 {
 	struct ehci_hcd		*ehci = hcd_to_ehci (hcd);
-	struct ehci_qh		*qh = (struct ehci_qh *) urb->hcpriv;
+	struct ehci_qh		*qh;
 	unsigned long		flags;
+	int			maybe_irq = 1;
 
-	ehci_vdbg (ehci, "urb_dequeue %p qh %p state %d\n",
-		urb, qh, qh->qh_state);
-
+	spin_lock_irqsave (&ehci->lock, flags);
 	switch (usb_pipetype (urb->pipe)) {
 	// case PIPE_CONTROL:
 	// case PIPE_BULK:
 	default:
-		spin_lock_irqsave (&ehci->lock, flags);
-		if (ehci->reclaim) {
-			vdbg ("dq %p: reclaim = %p, %s",
-				qh, ehci->reclaim, RUN_CONTEXT);
-			if (qh == ehci->reclaim) {
-				/* unlinking qh for another queued urb? */
-				spin_unlock_irqrestore (&ehci->lock, flags);
-				return 0;
-			}
-			if (in_interrupt ()) {
-				spin_unlock_irqrestore (&ehci->lock, flags);
-				return -EAGAIN;
-			}
+		qh = (struct ehci_qh *) urb->hcpriv;
+		if (!qh)
+			break;
 		while (qh->qh_state == QH_STATE_LINKED
 				&& ehci->reclaim
-					&& ehci->hcd.state != USB_STATE_HALT
+				&& HCD_IS_RUNNING (ehci->hcd.state)
 				) {
 			spin_unlock_irqrestore (&ehci->lock, flags);
-				/* let pending unlinks complete */
+
+			if (maybe_irq) {
+				if (in_interrupt ())
+					return -EAGAIN;
+				maybe_irq = 0;
+			}
+			/* let pending unlinks complete, so this can start */
 			wait_ms (1);
+
 			spin_lock_irqsave (&ehci->lock, flags);
 		}
-		}
+		if (!HCD_IS_RUNNING (ehci->hcd.state) && ehci->reclaim)
+			end_unlink_async (ehci, NULL);
+
+		/* something else might have unlinked the qh by now */
 		if (qh->qh_state == QH_STATE_LINKED)
 			start_unlink_async (ehci, qh);
-		spin_unlock_irqrestore (&ehci->lock, flags);
 		break;
 
 	case PIPE_INTERRUPT:
-		spin_lock_irqsave (&ehci->lock, flags);
+		qh = (struct ehci_qh *) urb->hcpriv;
+		if (!qh)
+			break;
 		if (qh->qh_state == QH_STATE_LINKED) {
 			/* messy, can spin or block a microframe ... */
 			intr_deschedule (ehci, qh, 1);
 			/* qh_state == IDLE */
 		}
-		qh_completions (ehci, qh);
+		qh_completions (ehci, qh, NULL);
 
 		/* reschedule QH iff another request is queued */
 		if (!list_empty (&qh->qtd_list)
@@ -817,7 +810,6 @@ static int ehci_urb_dequeue (struct usb_hcd *hcd, struct urb *urb)
 			}
 			return status;
 		}
-		spin_unlock_irqrestore (&ehci->lock, flags);
 		break;
 
 	case PIPE_ISOCHRONOUS:
@@ -828,6 +820,7 @@ static int ehci_urb_dequeue (struct usb_hcd *hcd, struct urb *urb)
 		urb->transfer_flags |= EHCI_STATE_UNLINK;
 		break;
 	}
+	spin_unlock_irqrestore (&ehci->lock, flags);
 	return 0;
 }
 

drivers/usb/host/ehci-hub.c

@@ -315,7 +315,7 @@ static int ehci_hub_control (
 					wIndex + 1);
 				temp |= PORT_OWNER;
 			} else {
-				ehci_vdbg (ehci, "port %d reset", wIndex + 1);
+				ehci_vdbg (ehci, "port %d reset\n", wIndex + 1);
 				temp |= PORT_RESET;
 				temp &= ~PORT_PE;
 

drivers/usb/host/ehci-mem.c

@@ -73,8 +73,11 @@ static struct ehci_qtd *ehci_qtd_alloc (struct ehci_hcd *ehci, int flags)
 	dma_addr_t		dma;
 
 	qtd = pci_pool_alloc (ehci->qtd_pool, flags, &dma);
-	if (qtd != 0)
+	if (qtd != 0) {
 		ehci_qtd_init (qtd, dma);
+		if (ehci->async)
+			qtd->hw_alt_next = ehci->async->hw_alt_next;
+	}
 	return qtd;
 }
 

drivers/usb/host/ehci-sched.c

@@ -495,7 +495,8 @@ static unsigned
 intr_complete (
 	struct ehci_hcd	*ehci,
 	unsigned	frame,
-	struct ehci_qh	*qh
+	struct ehci_qh	*qh,
+	struct pt_regs	*regs
 ) {
 	unsigned	count;
 
@@ -509,7 +510,7 @@ intr_complete (
 	}
 	
 	/* handle any completions */
-	count = qh_completions (ehci, qh);
+	count = qh_completions (ehci, qh, regs);
 
 	if (unlikely (list_empty (&qh->qtd_list)))
 		intr_deschedule (ehci, qh, 0);
@@ -867,7 +868,8 @@ static unsigned
 itd_complete (
 	struct ehci_hcd	*ehci,
 	struct ehci_itd	*itd,
-	unsigned	uframe
+	unsigned	uframe,
+	struct pt_regs	*regs
 ) {
 	struct urb				*urb = itd->urb;
 	struct usb_iso_packet_descriptor	*desc;
@@ -922,7 +924,7 @@ itd_complete (
 
 	/* complete() can reenter this HCD */
 	spin_unlock (&ehci->lock);
-	usb_hcd_giveback_urb (&ehci->hcd, urb, NULL);
+	usb_hcd_giveback_urb (&ehci->hcd, urb, regs);
 	spin_lock (&ehci->lock);
 
 	/* defer stopping schedule; completion can submit */
@@ -973,7 +975,7 @@ static int itd_submit (struct ehci_hcd *ehci, struct urb *urb, int mem_flags)
 /*-------------------------------------------------------------------------*/
 
 static void
-scan_periodic (struct ehci_hcd *ehci)
+scan_periodic (struct ehci_hcd *ehci, struct pt_regs *regs)
 {
 	unsigned	frame, clock, now_uframe, mod;
 	unsigned	count = 0;
@@ -999,14 +1001,6 @@ scan_periodic (struct ehci_hcd *ehci)
 		u32			type, *hw_p;
 		unsigned		uframes;
 
-		/* keep latencies down: let any irqs in */
-		if (count > max_completions) {
-			spin_unlock_irq (&ehci->lock);
-			cpu_relax ();
-			count = 0;
-			spin_lock_irq (&ehci->lock);
-		}
-
 restart:
 		/* scan schedule to _before_ current frame index */
 		if (frame == clock)
@@ -1031,7 +1025,7 @@ scan_periodic (struct ehci_hcd *ehci)
 				temp = q.qh->qh_next;
 				type = Q_NEXT_TYPE (q.qh->hw_next);
 				count += intr_complete (ehci, frame,
-						qh_get (q.qh));
+						qh_get (q.qh), regs);
 				qh_put (ehci, q.qh);
 				q = temp;
 				break;
@@ -1064,7 +1058,7 @@ scan_periodic (struct ehci_hcd *ehci)
 
 						/* might free q.itd ... */
 						count += itd_complete (ehci,
-							temp.itd, uf);
+							temp.itd, uf, regs);
 						break;
 					}
 				}