USB: musb: fix isochronous TXDMA (take 2)

Multi-frame isochronous TX URBs transfers in DMA mode never
complete with CPPI DMA because musb_host_tx() doesn't restart
DMA on the second frame, only emitting a debug message.
With Inventra DMA they complete, but in PIO mode.  To fix:

 - Factor out programming of the DMA transfer from
   musb_ep_program() into musb_tx_dma_program();

 - Reorder the code at the end of musb_host_tx() to
   facilitate the fallback to PIO iff DMA fails;

 - Handle the buffer offset consistently for both
   PIO and DMA modes;

 - Add an argument to musb_ep_program() for the same
   reason (it only worked correctly with non-zero
   offset of the first frame in PIO mode);

 - Set the completed isochronous frame descriptor's
   'actual_length' and 'status' fields correctly in
   DMA mode.

Also, since CPPI reportedly doesn't like sending isochronous
packets in the RNDIS mode, change the criterion for this
mode to be used only for multi-packet transfers.  (There's
no need for that mode in the single-packet case anyway.)

[ dbrownell@users.sourceforge.net: split comment paragraph
into bullet list, shrink patch delta, style tweaks ]
Signed-off-by: Pavel Kiryukhin <pkiryukhin@ru.mvista.com>
Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/musb/cppi_dma.c

@@ -579,6 +579,7 @@ cppi_next_tx_segment(struct musb *musb, struct cppi_channel *tx)
 	 * trigger the "send a ZLP?" confusion.
 	 */
 	rndis = (maxpacket & 0x3f) == 0
+		&& length > maxpacket
 		&& length < 0xffff
 		&& (length % maxpacket) != 0;
 

drivers/usb/musb/musb_host.c

@@ -97,8 +97,8 @@
 
 
 static void musb_ep_program(struct musb *musb, u8 epnum,
-			struct urb *urb, unsigned int nOut,
-			u8 *buf, u32 len);
+			struct urb *urb, int is_out,
+			u8 *buf, u32 offset, u32 len);
 
 /*
  * Clear TX fifo. Needed to avoid BABBLE errors.
@@ -192,9 +192,10 @@ musb_start_urb(struct musb *musb, int is_in, struct musb_qh *qh)
 {
 	u16			frame;
 	u32			len;
-	void			*buf;
 	void __iomem		*mbase =  musb->mregs;
 	struct urb		*urb = next_urb(qh);
+	void			*buf = urb->transfer_buffer;
+	u32			offset = 0;
 	struct musb_hw_ep	*hw_ep = qh->hw_ep;
 	unsigned		pipe = urb->pipe;
 	u8			address = usb_pipedevice(pipe);
@@ -217,7 +218,7 @@ musb_start_urb(struct musb *musb, int is_in, struct musb_qh *qh)
 	case USB_ENDPOINT_XFER_ISOC:
 		qh->iso_idx = 0;
 		qh->frame = 0;
-		buf = urb->transfer_buffer + urb->iso_frame_desc[0].offset;
+		offset = urb->iso_frame_desc[0].offset;
 		len = urb->iso_frame_desc[0].length;
 		break;
 	default:		/* bulk, interrupt */
@@ -235,14 +236,14 @@ musb_start_urb(struct musb *musb, int is_in, struct musb_qh *qh)
 			case USB_ENDPOINT_XFER_ISOC:	s = "-iso"; break;
 			default:			s = "-intr"; break;
 			}; s; }),
-			epnum, buf, len);
+			epnum, buf + offset, len);
 
 	/* Configure endpoint */
 	if (is_in || hw_ep->is_shared_fifo)
 		hw_ep->in_qh = qh;
 	else
 		hw_ep->out_qh = qh;
-	musb_ep_program(musb, epnum, urb, !is_in, buf, len);
+	musb_ep_program(musb, epnum, urb, !is_in, buf, offset, len);
 
 	/* transmit may have more work: start it when it is time */
 	if (is_in)
@@ -253,7 +254,6 @@ musb_start_urb(struct musb *musb, int is_in, struct musb_qh *qh)
 	case USB_ENDPOINT_XFER_ISOC:
 	case USB_ENDPOINT_XFER_INT:
 		DBG(3, "check whether there's still time for periodic Tx\n");
-		qh->iso_idx = 0;
 		frame = musb_readw(mbase, MUSB_FRAME);
 		/* FIXME this doesn't implement that scheduling policy ...
 		 * or handle framecounter wrapping
@@ -634,14 +634,68 @@ musb_rx_reinit(struct musb *musb, struct musb_qh *qh, struct musb_hw_ep *ep)
 	ep->rx_reinit = 0;
 }
 
+static bool musb_tx_dma_program(struct dma_controller *dma,
+		struct musb_hw_ep *hw_ep, struct musb_qh *qh,
+		struct urb *urb, u32 offset, u32 length)
+{
+	struct dma_channel	*channel = hw_ep->tx_channel;
+	void __iomem		*epio = hw_ep->regs;
+	u16			pkt_size = qh->maxpacket;
+	u16			csr;
+	u8			mode;
+
+#ifdef	CONFIG_USB_INVENTRA_DMA
+	if (length > channel->max_len)
+		length = channel->max_len;
+
+	csr = musb_readw(epio, MUSB_TXCSR);
+	if (length > pkt_size) {
+		mode = 1;
+		csr |= MUSB_TXCSR_AUTOSET
+			| MUSB_TXCSR_DMAMODE
+			| MUSB_TXCSR_DMAENAB;
+	} else {
+		mode = 0;
+		csr &= ~(MUSB_TXCSR_AUTOSET | MUSB_TXCSR_DMAMODE);
+		csr |= MUSB_TXCSR_DMAENAB; /* against programmer's guide */
+	}
+	channel->desired_mode = mode;
+	musb_writew(epio, MUSB_TXCSR, csr);
+#else
+	if (!is_cppi_enabled() && !tusb_dma_omap())
+		return false;
+
+	channel->actual_len = 0;
+
+	/*
+	 * TX uses "RNDIS" mode automatically but needs help
+	 * to identify the zero-length-final-packet case.
+	 */
+	mode = (urb->transfer_flags & URB_ZERO_PACKET) ? 1 : 0;
+#endif
+
+	qh->segsize = length;
+
+	if (!dma->channel_program(channel, pkt_size, mode,
+			urb->transfer_dma + offset, length)) {
+		dma->channel_release(channel);
+		hw_ep->tx_channel = NULL;
+
+		csr = musb_readw(epio, MUSB_TXCSR);
+		csr &= ~(MUSB_TXCSR_AUTOSET | MUSB_TXCSR_DMAENAB);
+		musb_writew(epio, MUSB_TXCSR, csr | MUSB_TXCSR_H_WZC_BITS);
+		return false;
+	}
+	return true;
+}
 
 /*
  * Program an HDRC endpoint as per the given URB
  * Context: irqs blocked, controller lock held
  */
 static void musb_ep_program(struct musb *musb, u8 epnum,
-			struct urb *urb, unsigned int is_out,
-			u8 *buf, u32 len)
+			struct urb *urb, int is_out,
+			u8 *buf, u32 offset, u32 len)
 {
 	struct dma_controller	*dma_controller;
 	struct dma_channel	*dma_channel;
@@ -768,82 +822,9 @@ static void musb_ep_program(struct musb *musb, u8 epnum,
 		else
 			load_count = min((u32) packet_sz, len);
 
-#ifdef CONFIG_USB_INVENTRA_DMA
-		if (dma_channel) {
-			qh->segsize = min(len, dma_channel->max_len);
-			if (qh->segsize <= packet_sz)
-				dma_channel->desired_mode = 0;
-			else
-				dma_channel->desired_mode = 1;
-
-			if (dma_channel->desired_mode == 0) {
-				/* Against the programming guide */
-				csr |= (MUSB_TXCSR_DMAENAB);
-			} else
-				csr |= (MUSB_TXCSR_AUTOSET
-					| MUSB_TXCSR_DMAENAB
-					| MUSB_TXCSR_DMAMODE);
-			musb_writew(epio, MUSB_TXCSR, csr);
-
-			dma_ok = dma_controller->channel_program(
-					dma_channel, packet_sz,
-					dma_channel->desired_mode,
-					urb->transfer_dma,
-					qh->segsize);
-			if (dma_ok) {
-				load_count = 0;
-			} else {
-				dma_controller->channel_release(dma_channel);
-				if (is_out)
-					hw_ep->tx_channel = NULL;
-				else
-					hw_ep->rx_channel = NULL;
-				dma_channel = NULL;
-
-				/*
-				 * The programming guide says that we must
-				 * clear the DMAENAB bit before DMAMODE...
-				 */
-				csr = musb_readw(epio, MUSB_TXCSR);
-				csr &= ~(MUSB_TXCSR_DMAENAB
-						| MUSB_TXCSR_AUTOSET);
-				musb_writew(epio, MUSB_TXCSR, csr);
-				csr &= ~MUSB_TXCSR_DMAMODE;
-				musb_writew(epio, MUSB_TXCSR, csr);
-			}
-		}
-#endif
-
-		/* candidate for DMA */
-		if ((is_cppi_enabled() || tusb_dma_omap()) && dma_channel) {
-
-			/* Defer enabling DMA */
-			dma_channel->actual_len = 0L;
-			qh->segsize = len;
-
-			/* TX uses "rndis" mode automatically, but needs help
-			 * to identify the zero-length-final-packet case.
-			 */
-			dma_ok = dma_controller->channel_program(
-					dma_channel, packet_sz,
-					(urb->transfer_flags
-							& URB_ZERO_PACKET)
-						== URB_ZERO_PACKET,
-					urb->transfer_dma,
-					qh->segsize);
-			if (dma_ok) {
+		if (dma_channel && musb_tx_dma_program(dma_controller,
+					hw_ep, qh, urb, offset, len))
 			load_count = 0;
-			} else {
-				dma_controller->channel_release(dma_channel);
-				hw_ep->tx_channel = NULL;
-				dma_channel = NULL;
-
-				/* REVISIT there's an error path here that
-				 * needs handling:  can't do dma, but
-				 * there's no pio buffer address...
-				 */
-			}
-		}
 
 		if (load_count) {
 			/* PIO to load FIFO */
@@ -903,7 +884,7 @@ static void musb_ep_program(struct musb *musb, u8 epnum,
 						dma_channel, packet_sz,
 						!(urb->transfer_flags
 							& URB_SHORT_NOT_OK),
-						urb->transfer_dma,
+						urb->transfer_dma + offset,
 						qh->segsize);
 				if (!dma_ok) {
 					dma_controller->channel_release(
@@ -1146,8 +1127,8 @@ void musb_host_tx(struct musb *musb, u8 epnum)
 	int			pipe;
 	bool			done = false;
 	u16			tx_csr;
-	size_t			wLength = 0;
-	u8			*buf = NULL;
+	size_t			length = 0;
+	size_t			offset = 0;
 	struct urb		*urb;
 	struct musb_hw_ep	*hw_ep = musb->endpoints + epnum;
 	void __iomem		*epio = hw_ep->regs;
@@ -1165,7 +1146,7 @@ void musb_host_tx(struct musb *musb, u8 epnum)
 	/* with CPPI, DMA sometimes triggers "extra" irqs */
 	if (!urb) {
 		DBG(4, "extra TX%d ready, csr %04x\n", epnum, tx_csr);
-		goto finish;
+		return;
 	}
 
 	pipe = urb->pipe;
@@ -1202,7 +1183,7 @@ void musb_host_tx(struct musb *musb, u8 epnum)
 		musb_writew(epio, MUSB_TXCSR,
 				MUSB_TXCSR_H_WZC_BITS
 				| MUSB_TXCSR_TXPKTRDY);
-		goto finish;
+		return;
 	}
 
 	if (status) {
@@ -1234,8 +1215,7 @@ void musb_host_tx(struct musb *musb, u8 epnum)
 	/* second cppi case */
 	if (dma_channel_status(dma) == MUSB_DMA_STATUS_BUSY) {
 		DBG(4, "extra TX%d ready, csr %04x\n", epnum, tx_csr);
-		goto finish;
-
+		return;
 	}
 
 	if (is_dma_capable() && dma && !status) {
@@ -1299,25 +1279,25 @@ void musb_host_tx(struct musb *musb, u8 epnum)
 		}
 	}
 
-	/* REVISIT this looks wrong... */
 	if (!status || dma || usb_pipeisoc(pipe)) {
 		if (dma)
-			wLength = dma->actual_len;
+			length = dma->actual_len;
 		else
-			wLength = qh->segsize;
-		qh->offset += wLength;
+			length = qh->segsize;
+		qh->offset += length;
 
 		if (usb_pipeisoc(pipe)) {
 			struct usb_iso_packet_descriptor	*d;
 
 			d = urb->iso_frame_desc + qh->iso_idx;
-			d->actual_length = qh->segsize;
+			d->actual_length = length;
+			d->status = status;
 			if (++qh->iso_idx >= urb->number_of_packets) {
 				done = true;
 			} else {
 				d++;
-				buf = urb->transfer_buffer + d->offset;
-				wLength = d->length;
+				offset = d->offset;
+				length = d->length;
 			}
 		} else if (dma) {
 			done = true;
@@ -1330,10 +1310,8 @@ void musb_host_tx(struct musb *musb, u8 epnum)
 						& URB_ZERO_PACKET))
 				done = true;
 			if (!done) {
-				buf = urb->transfer_buffer
-						+ qh->offset;
-				wLength = urb->transfer_buffer_length
-						- qh->offset;
+				offset = qh->offset;
+				length = urb->transfer_buffer_length - offset;
 			}
 		}
 	}
@@ -1352,28 +1330,31 @@ void musb_host_tx(struct musb *musb, u8 epnum)
 		urb->status = status;
 		urb->actual_length = qh->offset;
 		musb_advance_schedule(musb, urb, hw_ep, USB_DIR_OUT);
+		return;
+	} else	if (usb_pipeisoc(pipe) && dma) {
+		if (musb_tx_dma_program(musb->dma_controller, hw_ep, qh, urb,
+				offset, length))
+			return;
+	} else	if (tx_csr & MUSB_TXCSR_DMAENAB) {
+		DBG(1, "not complete, but DMA enabled?\n");
+		return;
+	}
 
-	} else if (!(tx_csr & MUSB_TXCSR_DMAENAB)) {
-		/* WARN_ON(!buf); */
-
-		/* REVISIT:  some docs say that when hw_ep->tx_double_buffered,
-		 * (and presumably, fifo is not half-full) we should write TWO
-		 * packets before updating TXCSR ... other docs disagree ...
+	/*
+	 * PIO: start next packet in this URB.
+	 *
+	 * REVISIT: some docs say that when hw_ep->tx_double_buffered,
+	 * (and presumably, FIFO is not half-full) we should write *two*
+	 * packets before updating TXCSR; other docs disagree...
 	 */
-		/* PIO:  start next packet in this URB */
-		if (wLength > qh->maxpacket)
-			wLength = qh->maxpacket;
-		musb_write_fifo(hw_ep, wLength, buf);
-		qh->segsize = wLength;
+	if (length > qh->maxpacket)
+		length = qh->maxpacket;
+	musb_write_fifo(hw_ep, length, urb->transfer_buffer + offset);
+	qh->segsize = length;
 
 	musb_ep_select(mbase, epnum);
 	musb_writew(epio, MUSB_TXCSR,
 			MUSB_TXCSR_H_WZC_BITS | MUSB_TXCSR_TXPKTRDY);
-	} else
-		DBG(1, "not complete, but dma enabled?\n");
-
-finish:
-	return;
 }