[PATCH] [ALSA] sparc dbri: ring buffered version

["Krzysztof Helt" <krzysztof.h1@wp.pl>]

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From: Krzysztof Helt (krzysztof.h1@wp.pl)

It is a complete rework of low level layer to work on ring
buffers for comands and data descriptors. This removes annoying
noise due to delay in data buffer switching.

Signed-off-by: Krzysztof Helt (krzysztof.h1@wp.pl)
---
This patch requires the 8 previous patches I sent to the
alsa-devel list.

Now, DBRI commands can be sent without waiting for the previous
ones to finish and data is sent through the DMA continously from
the ring buffer.

With this patch the ALSA DBRI driver reached the sound quality of
the old kernel 2.4 driver.

The driver needs more work (which I try to do in fre time):
- correct support of stereo and mono modes in 8 and 16 bit
- recording

Regards,
Krzysztof Helt

----------------------------------------------------
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--- alsa-driver-1.0.12rc2/alsa-kernel/sparc/dbri.c	2006-08-20 19:05:15.000000000 +0200
+++ linux-2.6.17a/sound/sparc/dbri.c	2006-08-20 19:11:23.000000000 +0200
@@ -2,6 +2,8 @@
  * Driver for DBRI sound chip found on Sparcs.
  * Copyright (C) 2004, 2005 Martin Habets (mhabets@users.sourceforge.net)
  *
+ * Converted to ring buffered version by Krzysztof Helt (krzysztof.h1@wp.pl)
+ *
  * Based entirely upon drivers/sbus/audio/dbri.c which is:
  * Copyright (C) 1997 Rudolf Koenig (rfkoenig@immd4.informatik.uni-erlangen.de)
  * Copyright (C) 1998, 1999 Brent Baccala (baccala@freesoft.org)
@@ -260,7 +262,7 @@ struct dbri_mem {
  * the CPU and the DBRI
  */
 struct dbri_dma {
-	volatile s32 cmd[DBRI_NO_CMDS];	/* Place for commands       */
+	s32 cmd[DBRI_NO_CMDS];			/* Place for commands */
 	volatile s32 intr[DBRI_INT_BLK];	/* Interrupt field  */
 	struct dbri_mem desc[DBRI_NO_DESCS];	/* Xmit/receive descriptors */
 };
@@ -284,7 +286,6 @@ struct dbri_pipe {
 struct dbri_streaminfo {
 	struct snd_pcm_substream *substream;
 	u32 dvma_buffer;	/* Device view of Alsa DMA buffer */
-	int left;		/* # of bytes left in DMA buffer  */
 	int size;		/* Size of DMA buffer             */
 	size_t offset;		/* offset in user buffer          */
 	int pipe;		/* Data pipe used                 */
@@ -305,11 +306,11 @@ struct snd_dbri {
 
 	void __iomem *regs;	/* dbri HW regs */
 	int dbri_irqp;		/* intr queue pointer */
-	int wait_send;		/* sequence of command buffers send */
-	int wait_ackd;		/* sequence of command buffers acknowledged */
 
 	struct dbri_pipe pipes[DBRI_NO_PIPES];	/* DBRI's 32 data pipes */
 	int next_desc[DBRI_NO_DESCS];		/* Index of next desc, or -1 */
+	spinlock_t cmdlock;	/* Protects cmd queue accesses */
+	s32 *cmdptr;		/* Pointer to the last queued cmd */
 
 	int chi_bpf;
 
@@ -544,7 +545,7 @@ struct snd_dbri {
 #define DBRI_TD_TBC	(1<<0)	/* Transmit buffer Complete */
 #define DBRI_TD_STATUS(v)       ((v)&0xff)	/* Transmit status */
 			/* Maximum buffer size per TD: almost 8Kb */
-#define DBRI_TD_MAXCNT	((1 << 13) - 1)
+#define DBRI_TD_MAXCNT	((1 << 13) - 4)
 
 /* Receive descriptor defines */
 #define DBRI_RD_F	(1<<31)	/* End of Frame */
@@ -608,79 +609,110 @@ The list is terminated with a WAIT comma
 CPU interrupt to signal completion.
 
 Since the DBRI can run in parallel with the CPU, several means of
-synchronization present themselves.  The method implemented here is close
-to the original scheme (Rudolf's), and uses 2 counters (wait_send and
-wait_ackd) to synchronize the command buffer between the CPU and the DBRI.
-
-A more sophisticated scheme might involve a circular command buffer
-or an array of command buffers.  A routine could fill one with
-commands and link it onto a list.  When a interrupt signaled
-completion of the current command buffer, look on the list for
-the next one.
+synchronization present themselves. The method implemented here is only
+to use the dbri_cmdwait() to wait for execution of batch of sent commands.
+
+A circular command buffer is used here. A new command is being added 
+while other can be executed. The scheme works by adding two WAIT commands
+after each sent batch of commands. When the next batch is prepared it is
+added after the WAIT commands then the WAITs are replaced with single JUMP
+command to the new batch. The the DBRI is forced to reread the last WAIT 
+command (replaced by the JUMP by then). If the DBRI is still executing 
+previous commands the request to reread the WAIT command is ignored.
 
 Every time a routine wants to write commands to the DBRI, it must
-first call dbri_cmdlock() and get an initial pointer into dbri->dma->cmd
-in return. dbri_cmdlock() will block if the previous commands have not
-been completed yet. After this the commands can be written to the buffer,
-and dbri_cmdsend() is called with the final pointer value to send them
-to the DBRI.
+first call dbri_cmdlock() and get pointer to a free space in 
+dbri->dma->cmd buffer. After this, the commands can be written to 
+the buffer, and dbri_cmdsend() is called with the final pointer value 
+to send them to the DBRI.
 
 */
 
 static void dbri_process_interrupt_buffer(struct snd_dbri * dbri);
 
-enum dbri_lock { NoGetLock, GetLock };
 #define MAXLOOPS 10
-
-static volatile s32 *dbri_cmdlock(struct snd_dbri * dbri, enum dbri_lock get)
+/*
+ * Wait for the current command string to execute
+ */
+static void dbri_cmdwait(struct snd_dbri *dbri)
 {
 	int maxloops = MAXLOOPS;
 
-#ifndef SMP
-	if ((get == GetLock) && spin_is_locked(&dbri->lock)) {
-		printk(KERN_ERR "DBRI: cmdlock called while in spinlock.");
-	}
-#endif
-
 	/* Delay if previous commands are still being processed */
-	while ((--maxloops) > 0 && (dbri->wait_send != dbri->wait_ackd)) {
+	while ((--maxloops) > 0 && (sbus_readl(dbri->regs + REG0) & D_P))
 		msleep_interruptible(1);
-	}
+
 	if (maxloops == 0) {
-		printk(KERN_ERR "DBRI: Chip never completed command buffer %d\n",
-			dbri->wait_send);
+		printk(KERN_ERR "DBRI: Chip never completed command buffer\n");
 	} else {
 		dprintk(D_CMD, "Chip completed command buffer (%d)\n",
 			MAXLOOPS - maxloops - 1);
 	}
+}
+/*
+ * Lock the command queue and returns pointer to a space for len cmd words
+ * It locks the cmdlock spinlock.
+ */
+static s32 *dbri_cmdlock(struct snd_dbri * dbri, int len)
+{
+	/* Space for 2 WAIT cmds (replaced later by 1 JUMP cmd) */
+	len += 2;
+	spin_lock(&dbri->cmdlock);
+	if (dbri->cmdptr - dbri->dma->cmd + len < DBRI_NO_CMDS - 2)
+		return dbri->cmdptr + 2;
+	else if (len < sbus_readl(dbri->regs + REG8) - dbri->dma_dvma)
+		return dbri->dma->cmd;
+	else
+		printk(KERN_ERR "DBRI: no space for commands.");
 
-	/*if (get == GetLock) spin_lock(&dbri->lock); */
-	return &dbri->dma->cmd[0];
+	return 0;
 }
 
-static void dbri_cmdsend(struct snd_dbri * dbri, volatile s32 * cmd)
+/*
+ * Send prepared cmd string. It works by writting a JMP cmd into
+ * the last WAIT cmd and force DBRI to reread the cmd.
+ * The JMP cmd points to the new cmd string.
+ * It also releases the cmdlock spinlock.
+ */
+static void dbri_cmdsend(struct snd_dbri * dbri, s32 * cmd,int len)
 {
-	volatile s32 *ptr;
+	s32 *ptr;
+	s32 tmp, addr;
+	static int wait_id = 0;
+
+	wait_id++;
+	wait_id &= 0xffff;	/* restrict it to a 16 bit counter. */
+	*(cmd) = DBRI_CMD(D_WAIT, 1, wait_id);
+	*(cmd+1) = DBRI_CMD(D_WAIT, 1, wait_id);
+
+	/* Replace the last command with JUMP */
+	addr = dbri->dma_dvma + (cmd - len - dbri->dma->cmd) * sizeof(s32);
+	*(dbri->cmdptr+1) = addr;
+	*(dbri->cmdptr) = DBRI_CMD(D_JUMP, 0, 0);
 
-	for (ptr = &dbri->dma->cmd[0]; ptr < cmd; ptr++) {
+#ifdef DBRI_DEBUG
+	if (cmd > dbri->cmdptr )
+		for (ptr = dbri->cmdptr; ptr < cmd+2; ptr++) {
+			dprintk(D_CMD, "cmd: %lx:%08x\n", (unsigned long)ptr, *ptr);
+		}
+	else {
+		ptr = dbri->cmdptr;
 		dprintk(D_CMD, "cmd: %lx:%08x\n", (unsigned long)ptr, *ptr);
+		ptr = dbri->cmdptr+1;
+		dprintk(D_CMD, "cmd: %lx:%08x\n", (unsigned long)ptr, *ptr);
+		for (ptr = dbri->dma->cmd; ptr < cmd+2; ptr++) {
+			dprintk(D_CMD, "cmd: %lx:%08x\n", (unsigned long)ptr, *ptr);
+		}
 	}
+#endif
 
-	if ((cmd - &dbri->dma->cmd[0]) >= DBRI_NO_CMDS - 1) {
-		printk(KERN_ERR "DBRI: Command buffer overflow! (bug in driver)\n");
-		/* Ignore the last part. */
-		cmd = &dbri->dma->cmd[DBRI_NO_CMDS - 3];
-	}
-
-	dbri->wait_send++;
-	dbri->wait_send &= 0xffff;	/* restrict it to a 16 bit counter. */
-	*(cmd++) = DBRI_CMD(D_PAUSE, 0, 0);
-	*(cmd++) = DBRI_CMD(D_WAIT, 1, dbri->wait_send);
-
-	/* Set command pointer and signal it is valid. */
-	sbus_writel(dbri->dma_dvma, dbri->regs + REG8);
+	/* Reread the last command */
+	tmp = sbus_readl(dbri->regs + REG0);
+	tmp |= D_P;
+	sbus_writel(tmp, dbri->regs + REG0);
 
-	/*spin_unlock(&dbri->lock); */
+	dbri->cmdptr = cmd;
+	spin_unlock(&dbri->cmdlock);
 }
 
 /* Lock must be held when calling this */
@@ -709,7 +741,7 @@ static void dbri_reset(struct snd_dbri *
 /* Lock must not be held before calling this */
 static void dbri_initialize(struct snd_dbri * dbri)
 {
-	volatile s32 *cmd;
+	s32 *cmd;
 	u32 dma_addr;
 	unsigned long flags;
 	int n;
@@ -718,14 +750,11 @@ static void dbri_initialize(struct snd_d
 
 	dbri_reset(dbri);
 
-	cmd = dbri_cmdlock(dbri, NoGetLock);
-	dprintk(D_GEN, "init: cmd: %p, int: %p\n",
-		&dbri->dma->cmd[0], &dbri->dma->intr[0]);
-
 	/* Initialize pipes */
 	for (n = 0; n < DBRI_NO_PIPES; n++)
 		dbri->pipes[n].desc = dbri->pipes[n].first_desc = -1;
 
+	spin_lock_init(&dbri->cmdlock);
 	/*
 	 * Initialize the interrupt ringbuffer.
 	 */
@@ -735,10 +764,19 @@ static void dbri_initialize(struct snd_d
 	/*
 	 * Set up the interrupt queue
 	 */
+	spin_lock(&dbri->cmdlock);
+	cmd = dbri->cmdptr = dbri->dma->cmd;
 	*(cmd++) = DBRI_CMD(D_IIQ, 0, 0);
 	*(cmd++) = dma_addr;
+	*(cmd++) = DBRI_CMD(D_PAUSE, 0, 0);
+	dbri->cmdptr = cmd;
+	*(cmd++) = DBRI_CMD(D_WAIT, 1, 0);
+	*(cmd++) = DBRI_CMD(D_WAIT, 1, 0);
+	dma_addr = dbri->dma_dvma + dbri_dma_off(cmd, 0);
+	sbus_writel(dma_addr, dbri->regs + REG8);
+	spin_unlock(&dbri->cmdlock);
+	dbri_cmdwait(dbri);
 
-	dbri_cmdsend(dbri, cmd);
 	spin_unlock_irqrestore(&dbri->lock, flags);
 }
 
@@ -770,7 +808,7 @@ static void reset_pipe(struct snd_dbri *
 {
 	int sdp;
 	int desc;
-	volatile int *cmd;
+	s32 *cmd;
 
 	if (pipe < 0 || pipe > DBRI_MAX_PIPE) {
 		printk(KERN_ERR "DBRI: reset_pipe called with illegal pipe number\n");
@@ -783,16 +821,18 @@ static void reset_pipe(struct snd_dbri *
 		return;
 	}
 
-	cmd = dbri_cmdlock(dbri, NoGetLock);
+	cmd = dbri_cmdlock(dbri, 3);
 	*(cmd++) = DBRI_CMD(D_SDP, 0, sdp | D_SDP_C | D_SDP_P);
 	*(cmd++) = 0;
-	dbri_cmdsend(dbri, cmd);
+	*(cmd++) = DBRI_CMD(D_PAUSE, 0, 0);
+	dbri_cmdsend(dbri, cmd, 3);
 
 	desc = dbri->pipes[pipe].first_desc;
-	while (desc != -1) {
-		dbri->dma->desc[desc].nda = dbri->dma->desc[desc].ba = 0;
-		desc = dbri->next_desc[desc];
-	}
+	if ( desc >= 0)
+		do {
+			dbri->dma->desc[desc].nda = dbri->dma->desc[desc].ba = 0;
+			desc = dbri->next_desc[desc];
+		} while (desc != -1 && desc != dbri->pipes[pipe].first_desc);
 
 	dbri->pipes[pipe].desc = -1;
 	dbri->pipes[pipe].first_desc = -1;
@@ -828,7 +868,7 @@ static void link_time_slot(struct snd_db
 			   int prevpipe, int nextpipe,
 			   int length, int cycle)
 {
-	volatile s32 *cmd;
+	s32 *cmd;
 	int val;
 
 	if (pipe < 0 || pipe > DBRI_MAX_PIPE 
@@ -847,11 +887,10 @@ static void link_time_slot(struct snd_db
 	}
 
 	dbri->pipes[prevpipe].nextpipe = pipe;
-
 	dbri->pipes[pipe].nextpipe = nextpipe;
 	dbri->pipes[pipe].length = length;
 
-	cmd = dbri_cmdlock(dbri, NoGetLock);
+	cmd = dbri_cmdlock(dbri, 4);
 
 	if (dbri->pipes[pipe].sdp & D_SDP_TO_SER) {
 		/* Deal with CHI special case:
@@ -874,25 +913,27 @@ static void link_time_slot(struct snd_db
 		    D_TS_LEN(length) | D_TS_CYCLE(cycle) | D_TS_NEXT(nextpipe);
 		*(cmd++) = 0;
 	}
+	*(cmd++) = DBRI_CMD(D_PAUSE, 0, 0);
 
-	dbri_cmdsend(dbri, cmd);
+	dbri_cmdsend(dbri, cmd, 4);
 }
 
 static void unlink_time_slot(struct snd_dbri * dbri, int pipe,
 			     enum in_or_out direction, int prevpipe,
 			     int nextpipe)
 {
-	volatile s32 *cmd;
+	s32 *cmd;
 	int val;
 
 	if (pipe < 0 || pipe > DBRI_MAX_PIPE 
-			|| prevpipe < 0 || prevpipe > DBRI_MAX_PIPE) {
+			|| prevpipe < 0 || prevpipe > DBRI_MAX_PIPE
+			|| nextpipe < 0 || nextpipe > DBRI_MAX_PIPE) {
 		printk(KERN_ERR 
 		    "DBRI: unlink_time_slot called with illegal pipe number\n");
 		return;
 	}
 
-	cmd = dbri_cmdlock(dbri, NoGetLock);
+	cmd = dbri_cmdlock(dbri, 4);
 
 	if (direction == PIPEinput) {
 		val = D_DTS_VI | D_DTS_DEL | D_DTS_PRVIN(prevpipe) | pipe;
@@ -905,8 +946,9 @@ static void unlink_time_slot(struct snd_
 		*(cmd++) = 0;
 		*(cmd++) = D_TS_NEXT(nextpipe);
 	}
+	*(cmd++) = DBRI_CMD(D_PAUSE, 0, 0);
 
-	dbri_cmdsend(dbri, cmd);
+	dbri_cmdsend(dbri, cmd, 4);
 }
 
 /* xmit_fixed() / recv_fixed()
@@ -925,7 +967,7 @@ static void unlink_time_slot(struct snd_
  */
 static void xmit_fixed(struct snd_dbri * dbri, int pipe, unsigned int data)
 {
-	volatile s32 *cmd;
+	s32 *cmd;
 
 	if (pipe < 16 || pipe > DBRI_MAX_PIPE) {
 		printk(KERN_ERR "DBRI: xmit_fixed: Illegal pipe number\n");
@@ -952,12 +994,14 @@ static void xmit_fixed(struct snd_dbri *
 	if (dbri->pipes[pipe].sdp & D_SDP_MSB)
 		data = reverse_bytes(data, dbri->pipes[pipe].length);
 
-	cmd = dbri_cmdlock(dbri, GetLock);
+	cmd = dbri_cmdlock(dbri, 3);
 
 	*(cmd++) = DBRI_CMD(D_SSP, 0, pipe);
 	*(cmd++) = data;
+	*(cmd++) = DBRI_CMD(D_PAUSE, 0, 0);
 
-	dbri_cmdsend(dbri, cmd);
+	dbri_cmdsend(dbri, cmd, 3);
+	dbri_cmdwait(dbri);
 }
 
 static void recv_fixed(struct snd_dbri * dbri, int pipe, volatile __u32 * ptr)
@@ -991,6 +1035,8 @@ static void recv_fixed(struct snd_dbri *
  * and work by building chains of descriptors which identify the
  * data buffers.  Buffers too large for a single descriptor will
  * be spread across multiple descriptors.
+ *
+ * All descriptors create a ring buffer.
  */
 static int setup_descs(struct snd_dbri * dbri, int streamno, unsigned int period)
 {
@@ -1051,14 +1097,13 @@ static int setup_descs(struct snd_dbri *
 			return -1;
 		}
 
-		if (len > DBRI_TD_MAXCNT) {
-			mylen = DBRI_TD_MAXCNT;	/* 8KB - 1 */
-		} else {
+		if (len > DBRI_TD_MAXCNT)
+			mylen = DBRI_TD_MAXCNT;	/* 8KB - 4 */
+		else
 			mylen = len;
-		}
-		if (mylen > period) {
+
+		if (mylen > period)
 			mylen = period;
-		}
 
 		dbri->next_desc[desc] = -1;
 		dbri->dma->desc[desc].ba = dvma_buffer;
@@ -1067,17 +1112,17 @@ static int setup_descs(struct snd_dbri *
 		if (streamno == DBRI_PLAY) {
 			dbri->dma->desc[desc].word1 = DBRI_TD_CNT(mylen);
 			dbri->dma->desc[desc].word4 = 0;
-			if (first_desc != -1)
-				dbri->dma->desc[desc].word1 |= DBRI_TD_M;
+			dbri->dma->desc[desc].word1 |= 
+			    DBRI_TD_F | DBRI_TD_B;
 		} else {
 			dbri->dma->desc[desc].word1 = 0;
 			dbri->dma->desc[desc].word4 =
 			    DBRI_RD_B | DBRI_RD_BCNT(mylen);
 		}
 
-		if (first_desc == -1) {
+		if (first_desc == -1)
 			first_desc = desc;
-		} else {
+		else {
 			dbri->next_desc[last_desc] = desc;
 			dbri->dma->desc[last_desc].nda =
 			    dbri->dma_dvma + dbri_dma_off(desc, desc);
@@ -1093,21 +1138,28 @@ static int setup_descs(struct snd_dbri *
 		return -1;
 	}
 
-	dbri->dma->desc[last_desc].word1 &= ~DBRI_TD_M;
 	if (streamno == DBRI_PLAY) {
 		dbri->dma->desc[last_desc].word1 |=
-		    DBRI_TD_I | DBRI_TD_F | DBRI_TD_B;
+		    DBRI_TD_F | DBRI_TD_B;
+		dbri->dma->desc[last_desc].nda =
+		    dbri->dma_dvma + dbri_dma_off(desc, first_desc);
+		dbri->next_desc[last_desc] = first_desc;
 	}
 	dbri->pipes[info->pipe].first_desc = first_desc;
 	dbri->pipes[info->pipe].desc = first_desc;
 
-	for (desc = first_desc; desc != -1; desc = dbri->next_desc[desc]) {
+#ifdef DBRI_DEBUG
+	for (desc = first_desc; desc != -1; ) {
 		dprintk(D_DESC, "DESC %d: %08x %08x %08x %08x\n",
 			desc,
 			dbri->dma->desc[desc].word1,
 			dbri->dma->desc[desc].ba,
 			dbri->dma->desc[desc].nda, dbri->dma->desc[desc].word4);
+			desc = dbri->next_desc[desc];
+			if ( desc == first_desc )
+				break;
 	}
+#endif
 	return 0;
 }
 
@@ -1127,43 +1179,24 @@ enum master_or_slave { CHImaster, CHIsla
 static void reset_chi(struct snd_dbri * dbri, enum master_or_slave master_or_slave,
 		      int bits_per_frame)
 {
-	volatile s32 *cmd;
+	s32 *cmd;
 	int val;
-	static int chi_initialized = 0;	/* FIXME: mutex? */
-
-	if (!chi_initialized) {
-
-		cmd = dbri_cmdlock(dbri, GetLock);
 
-		/* Set CHI Anchor: Pipe 16 */
+	/* Set CHI Anchor: Pipe 16 */
 
-		val = D_DTS_VO | D_DTS_VI | D_DTS_INS 
-			| D_DTS_PRVIN(16) | D_PIPE(16) | D_DTS_PRVOUT(16);
-		*(cmd++) = DBRI_CMD(D_DTS, 0, val);
-		*(cmd++) = D_TS_ANCHOR | D_TS_NEXT(16);
-		*(cmd++) = D_TS_ANCHOR | D_TS_NEXT(16);
-
-		dbri->pipes[16].sdp = 1;
-		dbri->pipes[16].nextpipe = 16;
+	cmd = dbri_cmdlock(dbri, 4);
+	val = D_DTS_VO | D_DTS_VI | D_DTS_INS 
+		| D_DTS_PRVIN(16) | D_PIPE(16) | D_DTS_PRVOUT(16);
+	*(cmd++) = DBRI_CMD(D_DTS, 0, val);
+	*(cmd++) = D_TS_ANCHOR | D_TS_NEXT(16);
+	*(cmd++) = D_TS_ANCHOR | D_TS_NEXT(16);
+	*(cmd++) = DBRI_CMD(D_PAUSE, 0, 0);
+	dbri_cmdsend(dbri, cmd, 4);
 
-#if 0
-		chi_initialized++;
-#endif
-	} else {
-		int pipe;
+	dbri->pipes[16].sdp = 1;
+	dbri->pipes[16].nextpipe = 16;
 
-		for (pipe = 0; pipe < DBRI_NO_PIPES; pipe++ )
-			if ( pipe != 16 ) {
-				if (dbri->pipes[pipe].sdp & D_SDP_TO_SER)
-					unlink_time_slot(dbri, pipe, PIPEoutput,
-							 16, dbri->pipes[pipe].nextpipe);
-				else
-					unlink_time_slot(dbri, pipe, PIPEinput,
-							 16, dbri->pipes[pipe].nextpipe);
-			}
-  
-  		cmd = dbri_cmdlock(dbri, GetLock);
-	}
+	cmd = dbri_cmdlock(dbri, 4);
 
 	if (master_or_slave == CHIslave) {
 		/* Setup DBRI for CHI Slave - receive clock, frame sync (FS)
@@ -1202,8 +1235,9 @@ static void reset_chi(struct snd_dbri * 
 
 	*(cmd++) = DBRI_CMD(D_PAUSE, 0, 0);
 	*(cmd++) = DBRI_CMD(D_CDM, 0, D_CDM_XCE | D_CDM_XEN | D_CDM_REN);
+	*(cmd++) = DBRI_CMD(D_PAUSE, 0, 0);
 
-	dbri_cmdsend(dbri, cmd);
+	dbri_cmdsend(dbri, cmd, 4);
 }
 
 /*
@@ -1240,6 +1274,8 @@ static void cs4215_setup_pipes(struct sn
 	setup_pipe(dbri, 17, D_SDP_FIXED | D_SDP_TO_SER | D_SDP_MSB);
 	setup_pipe(dbri, 18, D_SDP_FIXED | D_SDP_FROM_SER | D_SDP_MSB);
 	setup_pipe(dbri, 19, D_SDP_FIXED | D_SDP_FROM_SER | D_SDP_MSB);
+
+	dbri_cmdwait(dbri);
 }
 
 static int cs4215_init_data(struct cs4215 *mm)
@@ -1271,7 +1307,7 @@ static int cs4215_init_data(struct cs421
 	mm->status = 0;
 	mm->version = 0xff;
 	mm->precision = 8;	/* For ULAW */
-	mm->channels = 2;
+	mm->channels = 1;
 
 	return 0;
 }
@@ -1554,7 +1590,6 @@ static int cs4215_init(struct snd_dbri *
 	}
 
 	cs4215_setup_pipes(dbri);
-
 	cs4215_init_data(&dbri->mm);
 
 	/* Enable capture of the status & version timeslots. */
@@ -1583,9 +1618,7 @@ buffer and calls dbri_process_one_interr
 Complicated interrupts are handled by dedicated functions (which
 appear first in this file).  Any pending interrupts can be serviced by
 calling dbri_process_interrupt_buffer(), which works even if the CPU's
-interrupts are disabled.  This function is used by dbri_cmdlock()
-to make sure we're synced up with the chip before each command sequence,
-even if we're running cli'ed.
+interrupts are disabled.
 
 */
 
@@ -1594,11 +1627,10 @@ even if we're running cli'ed.
  * Transmit the current TD's for recording/playing, if needed.
  * For playback, ALSA has filled the DMA memory with new data (we hope).
  */
-static void xmit_descs(unsigned long data)
+static void xmit_descs(struct snd_dbri *dbri)
 {
-	struct snd_dbri *dbri = (struct snd_dbri *) data;
 	struct dbri_streaminfo *info;
-	volatile s32 *cmd;
+	s32 *cmd;
 	unsigned long flags;
 	int first_td;
 
@@ -1609,7 +1641,7 @@ static void xmit_descs(unsigned long dat
 	info = &dbri->stream_info[DBRI_REC];
 	spin_lock_irqsave(&dbri->lock, flags);
 
-	if ((info->left >= info->size) && (info->pipe >= 0)) {
+	if (info->pipe >= 0) {
 		first_td = dbri->pipes[info->pipe].first_desc;
 
 		dprintk(D_DESC, "xmit_descs rec @ TD %d\n", first_td);
@@ -1619,16 +1651,15 @@ static void xmit_descs(unsigned long dat
 			goto play;
 		}
 
-		cmd = dbri_cmdlock(dbri, NoGetLock);
+		cmd = dbri_cmdlock(dbri, 2);
 		*(cmd++) = DBRI_CMD(D_SDP, 0,
 				    dbri->pipes[info->pipe].sdp
 				    | D_SDP_P | D_SDP_EVERY | D_SDP_C);
 		*(cmd++) = dbri->dma_dvma + dbri_dma_off(desc, first_td);
-		dbri_cmdsend(dbri, cmd);
+		dbri_cmdsend(dbri, cmd, 2);
 
 		/* Reset our admin of the pipe & bytes read. */
 		dbri->pipes[info->pipe].desc = first_td;
-		info->left = 0;
 	}
 
 play:
@@ -1638,33 +1669,27 @@ play:
 	info = &dbri->stream_info[DBRI_PLAY];
 	spin_lock_irqsave(&dbri->lock, flags);
 
-	if ((info->left <= 0) && (info->pipe >= 0)) {
+	if (info->pipe >= 0) {
 		first_td = dbri->pipes[info->pipe].first_desc;
 
 		dprintk(D_DESC, "xmit_descs play @ TD %d\n", first_td);
 
 		/* Stream could be closed by the time we run. */
-		if (first_td < 0) {
-			spin_unlock_irqrestore(&dbri->lock, flags);
-			return;
-		}
-
-		cmd = dbri_cmdlock(dbri, NoGetLock);
-		*(cmd++) = DBRI_CMD(D_SDP, 0,
-				    dbri->pipes[info->pipe].sdp
-				    | D_SDP_P | D_SDP_EVERY | D_SDP_C);
-		*(cmd++) = dbri->dma_dvma + dbri_dma_off(desc, first_td);
-		dbri_cmdsend(dbri, cmd);
+		if (first_td >= 0) {
+			cmd = dbri_cmdlock(dbri, 2);
+			*(cmd++) = DBRI_CMD(D_SDP, 0,
+					    dbri->pipes[info->pipe].sdp
+					    | D_SDP_P | D_SDP_EVERY | D_SDP_C);
+			*(cmd++) = dbri->dma_dvma + dbri_dma_off(desc, first_td);
+			dbri_cmdsend(dbri, cmd, 2);
 
-		/* Reset our admin of the pipe & bytes written. */
-		dbri->pipes[info->pipe].desc = first_td;
-		info->left = info->size;
+			/* Reset our admin of the pipe & bytes written. */
+			dbri->pipes[info->pipe].desc = first_td;
+		}
 	}
 	spin_unlock_irqrestore(&dbri->lock, flags);
 }
 
-static DECLARE_TASKLET(xmit_descs_task, xmit_descs, 0);
-
 /* transmission_complete_intr()
  *
  * Called by main interrupt handler when DBRI signals transmission complete
@@ -1684,7 +1709,6 @@ static void transmission_complete_intr(s
 	struct dbri_streaminfo *info;
 	int td;
 	int status;
-	int len;
 
 	info = &dbri->stream_info[DBRI_PLAY];
 
@@ -1703,20 +1727,7 @@ static void transmission_complete_intr(s
 		dprintk(D_INT, "TD %d, status 0x%02x\n", td, status);
 
 		dbri->dma->desc[td].word4 = 0;	/* Reset it for next time. */
-		len = DBRI_RD_CNT(dbri->dma->desc[td].word1);
-		info->offset += len;
-		info->left -= len;
-
-		/* On the last TD, transmit them all again. */
-		if (dbri->next_desc[td] == -1) {
-			if (info->left > 0) {
-				printk(KERN_WARNING
-				       "%d bytes left after last transfer.\n",
-				       info->left);
-				info->left = 0;
-			}
-			tasklet_schedule(&xmit_descs_task);
-		}
+		info->offset += DBRI_RD_CNT(dbri->dma->desc[td].word1);
 
 		td = dbri->next_desc[td];
 		dbri->pipes[pipe].desc = td;
@@ -1749,7 +1760,6 @@ static void reception_complete_intr(stru
 
 	info = &dbri->stream_info[DBRI_REC];
 	info->offset += DBRI_RD_CNT(status);
-	info->left += DBRI_RD_CNT(status);
 
 	/* FIXME: Check status */
 
@@ -1757,6 +1767,7 @@ static void reception_complete_intr(stru
 		rd, DBRI_RD_STATUS(status), DBRI_RD_CNT(status));
 
 	/* On the last TD, transmit them all again. */
+#if 0
 	if (dbri->next_desc[rd] == -1) {
 		if (info->left > info->size) {
 			printk(KERN_WARNING
@@ -1765,6 +1776,7 @@ static void reception_complete_intr(stru
 		}
 		tasklet_schedule(&xmit_descs_task);
 	}
+#endif
 
 	/* Notify ALSA */
 	if (spin_is_locked(&dbri->lock)) {
@@ -1793,16 +1805,11 @@ static void dbri_process_one_interrupt(s
 			channel, code, rval);
 	}
 
-	if (channel == D_INTR_CMD && command == D_WAIT) {
-		dbri->wait_ackd = val;
-		if (dbri->wait_send != val) {
-			printk(KERN_ERR "Processing wait command %d when %d was send.\n",
-			       val, dbri->wait_send);
-		}
-		return;
-	}
-
 	switch (code) {
+	case D_INTR_CMDI:
+		if (command != D_WAIT)
+			printk(KERN_ERR "DBRI: Command read interrupt\n");
+		break;
 	case D_INTR_BRDY:
 		reception_complete_intr(dbri, channel);
 		break;
@@ -1815,8 +1822,10 @@ static void dbri_process_one_interrupt(s
 		 * resend SDP command with clear pipe bit (C) set
 		 */
 		{
-			volatile s32 *cmd;
-
+	/* FIXME: do something useful in case of underrun */
+			printk(KERN_ERR "DBRI: Underrun error\n");
+#if 0
+			s32 *cmd;
 			int pipe = channel;
 			int td = dbri->pipes[pipe].desc;
 
@@ -1827,6 +1836,7 @@ static void dbri_process_one_interrupt(s
 					    | D_SDP_P | D_SDP_C | D_SDP_2SAME);
 			*(cmd++) = dbri->dma_dvma + dbri_dma_off(desc, td);
 			dbri_cmdsend(dbri, cmd);
+#endif
 		}
 		break;
 	case D_INTR_FXDT:
@@ -1847,9 +1857,7 @@ static void dbri_process_one_interrupt(s
 /* dbri_process_interrupt_buffer advances through the DBRI's interrupt
  * buffer until it finds a zero word (indicating nothing more to do
  * right now).  Non-zero words require processing and are handed off
- * to dbri_process_one_interrupt AFTER advancing the pointer.  This
- * order is important since we might recurse back into this function
- * and need to make sure the pointer has been advanced first.
+ * to dbri_process_one_interrupt AFTER advancing the pointer.
  */
 static void dbri_process_interrupt_buffer(struct snd_dbri * dbri)
 {
@@ -1919,8 +1927,6 @@ static irqreturn_t snd_dbri_interrupt(in
 
 	dbri_process_interrupt_buffer(dbri);
 
-	/* FIXME: Write 0 into regs to ACK interrupt */
-
 	spin_unlock(&dbri->lock);
 
 	return IRQ_HANDLED;
@@ -1962,7 +1968,6 @@ static int snd_dbri_open(struct snd_pcm_
 
 	spin_lock_irqsave(&dbri->lock, flags);
 	info->substream = substream;
-	info->left = 0;
 	info->offset = 0;
 	info->dvma_buffer = 0;
 	info->pipe = -1;
@@ -1980,7 +1985,6 @@ static int snd_dbri_close(struct snd_pcm
 
 	dprintk(D_USR, "close audio output.\n");
 	info->substream = NULL;
-	info->left = 0;
 	info->offset = 0;
 
 	return 0;
@@ -2062,10 +2066,8 @@ static int snd_dbri_prepare(struct snd_p
 	info->size = snd_pcm_lib_buffer_bytes(substream);
 	if (DBRI_STREAMNO(substream) == DBRI_PLAY)
 		info->pipe = 4;	/* Send pipe */
-	else {
+	else
 		info->pipe = 6;	/* Receive pipe */
-		info->left = info->size;	/* To trigger submittal */
-	}
 
 	spin_lock_irq(&dbri->lock);
 
@@ -2093,14 +2095,11 @@ static int snd_dbri_trigger(struct snd_p
 	case SNDRV_PCM_TRIGGER_START:
 		dprintk(D_USR, "start audio, period is %d bytes\n",
 			(int)snd_pcm_lib_period_bytes(substream));
-		/* Enable & schedule the tasklet that re-submits the TDs. */
-		xmit_descs_task.data = (unsigned long)dbri;
-		tasklet_schedule(&xmit_descs_task);
+		/* Re-submit the TDs. */
+		xmit_descs(dbri);
 		break;
 	case SNDRV_PCM_TRIGGER_STOP:
 		dprintk(D_USR, "stop audio.\n");
-		/* Make the tasklet bail out immediately. */
-		xmit_descs_task.data = 0;
 		reset_pipe(dbri, info->pipe);
 		break;
 	default:
@@ -2118,8 +2117,8 @@ static snd_pcm_uframes_t snd_dbri_pointe
 
 	ret = bytes_to_frames(substream->runtime, info->offset)
 		% substream->runtime->buffer_size;
-	dprintk(D_USR, "I/O pointer: %ld frames, %d bytes left.\n",
-		ret, info->left);
+	dprintk(D_USR, "I/O pointer: %ld frames of %ld.\n",
+		ret, substream->runtime->buffer_size);
 	return ret;
 }