Another CPPI USB DMA issue

diff --git a/drivers/usb/musb/cppi41.h b/drivers/usb/musb/cppi41.h
index b4fce04..065b55f 100644
--- a/drivers/usb/musb/cppi41.h
+++ b/drivers/usb/musb/cppi41.h
@@ -536,9 +536,16 @@ struct cppi41_queue_obj {
 };
 
 static inline u32 cppi_readl(const void __iomem *addr)
-	{ return readl(addr); }
+{
+	u32 val = readl(addr);
+	trace_printk("cppi-readl %p: %08x\n", addr, val);
+	return val;
+}
 static inline void cppi_writel(u32 data, void __iomem *addr)
-	{ writel(data, addr); }
+{
+	trace_printk("cppi-Write %p: %08x\n", addr, data);
+	writel(data, addr);
+}
 /**
  * cppi41_queue_mgr_init - CPPI 4.1 queue manager initialization.
  * @q_mgr:	the queue manager to initialize
diff --git a/drivers/usb/musb/cppi41_dma.c b/drivers/usb/musb/cppi41_dma.c
index 1db49ab..5e184fa 100644
--- a/drivers/usb/musb/cppi41_dma.c
+++ b/drivers/usb/musb/cppi41_dma.c
@@ -520,6 +520,8 @@ static struct dma_channel *cppi41_channel_alloc(struct dma_controller
 
 	dev_dbg(musb->controller, "Allocated DMA %cx channel %d for EP%d\n", is_tx ? 'T' : 'R',
 	    ch_num, ep_num);
+	if (is_tx)
+		trace_printk("Allocated DMA Tx channel %d for EP%d\n", ch_num, ep_num);
 
 	return &cppi_ch->channel;
 }
@@ -632,6 +634,9 @@ static unsigned cppi41_next_tx_segment(struct cppi41_channel *tx_ch)
 	dev_dbg(musb->controller, "TX DMA%u, %s, maxpkt %u, %u PDs, addr %#x, len %u\n",
 	    tx_ch->ch_num, tx_ch->dma_mode ? "accelerated" : "transparent",
 	    pkt_size, num_pds, tx_ch->start_addr + tx_ch->curr_offset, length);
+	trace_printk("TX DMA%u, %s, maxpkt %u, %u PDs, addr %#x, len %u\n",
+	    tx_ch->ch_num, tx_ch->dma_mode ? "accelerated" : "transparent",
+	    pkt_size, num_pds, tx_ch->start_addr + tx_ch->curr_offset, length);
 
 	/* Enable txfifo empty interrupt logic for supported platform to make
 	 * sure last byte is transferred out of txfifo, this logic
diff --git a/drivers/usb/musb/musb_core.c b/drivers/usb/musb/musb_core.c
index 075aa5f..2147457 100644
--- a/drivers/usb/musb/musb_core.c
+++ b/drivers/usb/musb/musb_core.c
@@ -167,10 +167,18 @@ static inline void __tusb_musb_writeb(void __iomem *addr, unsigned offset,
 }
 
 static inline u8 __musb_readb(const void __iomem *addr, unsigned offset)
-	{ return readb(addr + offset); }
+{
+	u8 val = readb(addr + offset);
+
+	trace_printk("readb %p + %04x: %02x\n", addr, offset, val);
+	return val;
+}
 
 static inline void __musb_writeb(void __iomem *addr, unsigned offset, u8 data)
-	{ writeb(data, addr + offset); }
+{
+	trace_printk("Writeb %p + %04x: %02x\n", addr, offset, data);
+	writeb(data, addr + offset);
+}
 
 static int musb_ulpi_read(struct otg_transceiver *otg, u32 offset)
 {
diff --git a/drivers/usb/musb/musb_io.h b/drivers/usb/musb/musb_io.h
index af554fe..9f2a78d 100644
--- a/drivers/usb/musb/musb_io.h
+++ b/drivers/usb/musb/musb_io.h
@@ -61,17 +61,31 @@ static inline void writesb(const void __iomem *addr, const void *buf, int len)
 /* NOTE:  these offsets are all in bytes */
 
 static inline u16 musb_readw(const void __iomem *addr, unsigned offset)
-	{ return readw(addr + offset); }
+{
+	u16 val = readw(addr + offset);
+	trace_printk("readw %p + %04x: %04x\n", addr, offset, val);
+	return val;
+}
 
 static inline u32 musb_readl(const void __iomem *addr, unsigned offset)
-	{ return readl(addr + offset); }
+{
+	u32 val = readl(addr + offset);
+	trace_printk("readl %p + %04x: %08x\n", addr, offset, val);
+	return val;
+}
 
 
 static inline void musb_writew(void __iomem *addr, unsigned offset, u16 data)
-	{ writew(data, addr + offset); }
+{
+	trace_printk("Writew %p + %04x: %04x\n", addr, offset, data);
+	writew(data, addr + offset);
+}
 
 static inline void musb_writel(void __iomem *addr, unsigned offset, u32 data)
-	{ writel(data, addr + offset); }
+{
+	trace_printk("Writel %p + %04x: %08x\n", addr, offset, data);
+	writel(data, addr + offset);
+}
 
 #else
 
diff --git a/drivers/usb/musb/ti81xx.c b/drivers/usb/musb/ti81xx.c
index 9b23570..acc7f3a 100644
--- a/drivers/usb/musb/ti81xx.c
+++ b/drivers/usb/musb/ti81xx.c
@@ -736,7 +736,6 @@ static void otg_timer(unsigned long _musb)
 			    MUSB_INTR_VBUSERROR << USB_INTR_USB_SHIFT);
 		break;
 	case OTG_STATE_B_IDLE:
-		if (!is_peripheral_enabled(musb))
 			break;
 
 		/*
@@ -859,6 +858,7 @@ static irqreturn_t cppi41dma_Interrupt(int irq, void *hci)
 	if (gmusb[0] && (usb0_tx_intr || usb0_rx_intr)) {
 		dev_dbg(gmusb[0]->controller, "CPPI 4.1 IRQ: Tx %x, Rx %x\n",
 			usb0_tx_intr, usb0_rx_intr);
+		trace_printk("CPPI 4.1 IRQ: Tx %x, Rx %x\n", usb0_tx_intr, usb0_rx_intr);
 		spin_lock_irqsave(&gmusb[0]->lock, flags);
 		cppi41_completion(gmusb[0], usb0_rx_intr,
 					usb0_tx_intr);
@@ -1079,6 +1079,8 @@ static irqreturn_t ti81xx_interrupt(int irq, void *hci)
 	musb->int_usb =	(usbintr & USB_INTR_USB_MASK) >> USB_INTR_USB_SHIFT;
 
 	dev_dbg(musb->controller, "usbintr (%x) epintr(%x)\n", usbintr, epintr);
+	if (!musb->id)
+		trace_printk("usbintr (%x) epintr(%x)\n", usbintr, epintr);
 
 	if (musb->int_usb & MUSB_INTR_SOF) {
 		musb->sof_cnt++;

From 5fa70ec6e9e2afc13fdb3351b8d595f3aa885fae Mon Sep 17 00:00:00 2001
From: Bin Liu <b-liu@ti.com>
Date: Thu, 3 Dec 2015 10:14:44 -0600
Subject: [PATCH 2/2] usb: musb: cppi41: fix busy loop in txdma_completion_work

Due to the hardware issue of tx-dma early completin, a gadget driver
could pre-load a packet into TX FIFO, which sets txcsr TXPKTRDY and
FIFONOTEMPTY bits, which would be cleared until the host sends an IN
token. During this time txdma_completion_work() becomes a busy loop
checking those two txcsr bits.

One way to replicate the issue is with g_serial driver sending a
character on the the gadget side, but the host does not open the ACM
port to receive the char.

The fix is to put the work thread to sleep for 50us after looped for
4000 times. Since the sleep is interruptible, the work thread scheduling
for new tx channels will not be affected.

Signed-off-by: Bin Liu <b-liu@ti.com>
---
 drivers/usb/musb/cppi41_dma.c | 24 ++++++++----------------
 1 file changed, 8 insertions(+), 16 deletions(-)

diff --git a/drivers/usb/musb/cppi41_dma.c b/drivers/usb/musb/cppi41_dma.c
index 32380ac..3b3f4c8 100644
--- a/drivers/usb/musb/cppi41_dma.c
+++ b/drivers/usb/musb/cppi41_dma.c
@@ -114,7 +114,6 @@ struct cppi41_channel {
 	u8  txfifo_intr_first;
 	u8  xfer_state;
 	struct usb_pkt_desc *curr_pd;
-	int sched_cnt;
 };
 
 /**
@@ -315,7 +314,6 @@ static int __devinit cppi41_controller_start(struct dma_controller *controller)
 				     CPPI41_SRC_TAG_CH_NUM_SHIFT) |
 				    (tx_info->sub_ch_num <<
 				     CPPI41_SRC_TAG_SUB_CH_NUM_SHIFT);
-		cppi_ch->sched_cnt = 0;
 	}
 
 	/* Configure the Rx channels */
@@ -324,7 +322,6 @@ static int __devinit cppi41_controller_start(struct dma_controller *controller)
 		memset(cppi_ch, 0, sizeof(struct cppi41_channel));
 		cppi_ch->ch_num = i;
 		cppi_ch->channel.private_data = cppi;
-		cppi_ch->sched_cnt = 0;
 	}
 
 	/* Construct/store Tx PD packet info field for later use */
@@ -1417,6 +1414,7 @@ void txdma_completion_work(struct work_struct *data)
 	unsigned index;
 	u8 resched = 0;
 	unsigned long flags;
+	int slowchk=0;
 
 	while (1) {
 		for (index = 0; index < USB_CPPI41_NUM_CH; index++) {
@@ -1444,27 +1442,19 @@ void txdma_completion_work(struct work_struct *data)
 					(csr & (MUSB_TXCSR_TXPKTRDY |
 					MUSB_TXCSR_FIFONOTEMPTY))) {
 					resched = 1;
-					tx_ch->sched_cnt++;
-					if (tx_ch->sched_cnt < 4000)
-						continue;
 					dev_dbg(musb->controller,
 						"txdma comp work: TX%d csr %04x",
 						tx_ch->ch_num, csr);
-					msleep(1);
 				} else {
 					len = tx_ch->length -
 						tx_ch->curr_offset;
 					if (csr & (MUSB_TXCSR_TXPKTRDY |
 						MUSB_TXCSR_FIFONOTEMPTY)) {
 						resched = 1;
-						tx_ch->sched_cnt++;
 						tx_ch->count = 1;
-						if (tx_ch->sched_cnt < 4000)
-							continue;
 						dev_dbg(musb->controller,
 							"txdma comp work (2): TX%d csr %04x",
 							tx_ch->ch_num, csr);
-						msleep(1);
 						continue;
 					} else  if (tx_ch->zlp_queued && !len) {
 						/* send ZLP using PIO mode */
@@ -1485,8 +1475,6 @@ void txdma_completion_work(struct work_struct *data)
 						continue;
 					}
 
-					tx_ch->sched_cnt = 0;
-
 					if (len > 0) {
 						tx_ch->tx_complete = 0;
 						cppi41_next_tx_segment(tx_ch);
@@ -1507,11 +1495,15 @@ void txdma_completion_work(struct work_struct *data)
 				cond_resched();
 		}
 
-		if (resched) {
-			resched = 0;
+		if (!resched)
+			return;
+
+		resched = 0;
+		if (slowchk++ < 4000) {
 			cond_resched();
 		} else {
-			return ;
+			set_current_state(TASK_INTERRUPTIBLE);
+			schedule_timeout(usecs_to_jiffies(50));
 		}
 	}
 
-- 
1.9.1

From f5d498a03b68b325febff885daad867b2ba9983b Mon Sep 17 00:00:00 2001
From: Bin Liu <b-liu@ti.com>
Date: Thu, 17 Dec 2015 15:25:32 -0600
Subject: [PATCH] usb: musb: cppi41: fix throughput regression

---
 drivers/usb/musb/cppi41_dma.c | 63 ++++++++++++++++++++++++++++++++++++-------
 1 file changed, 54 insertions(+), 9 deletions(-)

diff --git a/drivers/usb/musb/cppi41_dma.c b/drivers/usb/musb/cppi41_dma.c
index 3b3f4c8..9fe0021 100644
--- a/drivers/usb/musb/cppi41_dma.c
+++ b/drivers/usb/musb/cppi41_dma.c
@@ -114,6 +114,7 @@ struct cppi41_channel {
 	u8  txfifo_intr_first;
 	u8  xfer_state;
 	struct usb_pkt_desc *curr_pd;
+	int sched_cnt;
 };
 
 /**
@@ -129,6 +130,7 @@ struct cppi41 {
 	struct cppi41_channel tx_cppi_ch[USB_CPPI41_NUM_CH];
 	struct cppi41_channel rx_cppi_ch[USB_CPPI41_NUM_CH];
 	struct work_struct      txdma_work;
+	struct work_struct      txdma_slow_work;
 	struct work_struct      rxdma_work;
 
 	struct usb_pkt_desc *pd_pool_head; /* Free PD pool head */
@@ -314,6 +316,7 @@ static int __devinit cppi41_controller_start(struct dma_controller *controller)
 				     CPPI41_SRC_TAG_CH_NUM_SHIFT) |
 				    (tx_info->sub_ch_num <<
 				     CPPI41_SRC_TAG_SUB_CH_NUM_SHIFT);
+		cppi_ch->sched_cnt = 0;
 	}
 
 	/* Configure the Rx channels */
@@ -322,6 +325,7 @@ static int __devinit cppi41_controller_start(struct dma_controller *controller)
 		memset(cppi_ch, 0, sizeof(struct cppi41_channel));
 		cppi_ch->ch_num = i;
 		cppi_ch->channel.private_data = cppi;
+		cppi_ch->sched_cnt = 0;
 	}
 
 	/* Construct/store Tx PD packet info field for later use */
@@ -1441,7 +1445,13 @@ void txdma_completion_work(struct work_struct *data)
 				if (!tx_ch->txfifo_intr_enable &&
 					(csr & (MUSB_TXCSR_TXPKTRDY |
 					MUSB_TXCSR_FIFONOTEMPTY))) {
-					resched = 1;
+					if (tx_ch->sched_cnt > 4000) {
+						tx_ch->tx_complete = 2;
+						slowchk = 1;
+					} else {
+						tx_ch->sched_cnt++;
+						resched = 1;
+					}
 					dev_dbg(musb->controller,
 						"txdma comp work: TX%d csr %04x",
 						tx_ch->ch_num, csr);
@@ -1450,7 +1460,13 @@ void txdma_completion_work(struct work_struct *data)
 						tx_ch->curr_offset;
 					if (csr & (MUSB_TXCSR_TXPKTRDY |
 						MUSB_TXCSR_FIFONOTEMPTY)) {
-						resched = 1;
+						if (tx_ch->sched_cnt++ > 4000) {
+							tx_ch->tx_complete = 2;
+							slowchk = 1;
+						} else {
+							tx_ch->sched_cnt++;
+							resched = 1;
+						}
 						tx_ch->count = 1;
 						dev_dbg(musb->controller,
 							"txdma comp work (2): TX%d csr %04x",
@@ -1475,6 +1491,8 @@ void txdma_completion_work(struct work_struct *data)
 						continue;
 					}
 
+					tx_ch->sched_cnt = 0;
+
 					if (len > 0) {
 						tx_ch->tx_complete = 0;
 						cppi41_next_tx_segment(tx_ch);
@@ -1495,18 +1513,44 @@ void txdma_completion_work(struct work_struct *data)
 				cond_resched();
 		}
 
-		if (!resched)
-			return;
-
-		resched = 0;
-		if (slowchk++ < 4000) {
+		if (resched) {
+			resched = 0;
 			cond_resched();
 		} else {
-			set_current_state(TASK_INTERRUPTIBLE);
-			schedule_timeout(usecs_to_jiffies(50));
+			if (slowchk) {
+				slowchk = 0;
+				schedule_work(&cppi->txdma_slow_work);
+			}
+			return ;
 		}
 	}
+}
+
+void txdma_completion_slow_work(struct work_struct *data)
+{
+	struct cppi41 *cppi = container_of(data, struct cppi41, txdma_slow_work);
+	struct cppi41_channel *tx_ch;
+	struct musb *musb = cppi->musb;
+	unsigned index;
+	int check = 0;
+
+	set_current_state(TASK_UNINTERRUPTIBLE);
+	schedule_timeout(msecs_to_jiffies(300));
+
+	for (index = 0; index < USB_CPPI41_NUM_CH; index++) {
+		tx_ch = &cppi->tx_cppi_ch[index];
+		if (tx_ch->tx_complete != 2)
+			continue;
+
+		tx_ch->tx_complete = 1;
+		check = 1;
+		dev_dbg(musb->controller,
+			"txdma slow comp work: TX%d",
+			tx_ch->ch_num);
+	}
 
+	if (check)
+		schedule_work(&cppi->txdma_work);
 }
 
 void cppi41_isoc_schedular(struct musb *musb)
@@ -1634,6 +1678,7 @@ cppi41_dma_controller_create(struct musb  *musb, void __iomem *mregs)
 	cppi->txfifo_intr_enable = musb->txfifo_intr_enable;
 	cppi->tx_isoc_sched_enable = musb->tx_isoc_sched_enable;
 	INIT_WORK(&cppi->txdma_work, txdma_completion_work);
+	INIT_WORK(&cppi->txdma_slow_work, txdma_completion_slow_work);
 	INIT_WORK(&cppi->rxdma_work, rxdma_completion_work);
 
 	/*
-- 
1.9.1