mISDN: Implement MISDN_CTRL_FILL_EMPTY for more drivers

MISDN_CTRL_FILL_EMPTY is a meachanism to send a fixed value (normally silence)
as long no data from upper layers is available. It can be used when recording
voice messages or with unidirectional protocols.

Signed-off-by: Karsten Keil <kkeil@linux-pingi.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

10 files changed, 240 insertions, 160 deletions

diff --git a/drivers/isdn/hardware/mISDN/avmfritz.c b/drivers/isdn/hardware/mISDN/avmfritz.c
index 7cd3a96..c6fa505 100644
--- a/drivers/isdn/hardware/mISDN/avmfritz.c
+++ b/drivers/isdn/hardware/mISDN/avmfritz.c
@@ -30,7 +30,7 @@
 #include "ipac.h"
 
 
-#define AVMFRITZ_REV	"2.2"
+#define AVMFRITZ_REV	"2.3"
 
 static int AVM_cnt;
 static int debug;
@@ -442,19 +442,26 @@ hdlc_fill_fifo(struct bchannel *bch)
 {
 	struct fritzcard *fc = bch->hw;
 	struct hdlc_hw *hdlc;
-	int count, fs, cnt = 0;
+	int count, fs, cnt = 0, idx, fillempty = 0;
 	u8 *p;
 	u32 *ptr, val, addr;
 
-	hdlc = &fc->hdlc[(bch->nr - 1) & 1];
-	if (!bch->tx_skb)
-		return;
-	count = bch->tx_skb->len - bch->tx_idx;
-	if (count <= 0)
-		return;
+	idx = (bch->nr - 1) & 1;
+	hdlc = &fc->hdlc[idx];
 	fs = (fc->type == AVM_FRITZ_PCIV2) ?
 		HDLC_FIFO_SIZE_V2 : HDLC_FIFO_SIZE_V1;
-	p = bch->tx_skb->data + bch->tx_idx;
+	if (!bch->tx_skb) {
+		if (!test_bit(FLG_TX_EMPTY, &bch->Flags))
+			return;
+		count = fs;
+		p = bch->fill;
+		fillempty = 1;
+	} else {
+		count = bch->tx_skb->len - bch->tx_idx;
+		if (count <= 0)
+			return;
+		p = bch->tx_skb->data + bch->tx_idx;
+	}
 	hdlc->ctrl.sr.cmd &= ~HDLC_CMD_XME;
 	if (count > fs) {
 		count = fs;
@@ -462,10 +469,14 @@ hdlc_fill_fifo(struct bchannel *bch)
 		if (test_bit(FLG_HDLC, &bch->Flags))
 			hdlc->ctrl.sr.cmd |= HDLC_CMD_XME;
 	}
-	pr_debug("%s: %s %d/%d/%d", fc->name, __func__, count,
-		 bch->tx_idx, bch->tx_skb->len);
 	ptr = (u32 *)p;
-	bch->tx_idx += count;
+	if (fillempty) {
+		pr_debug("%s.B%d: %d/%d/%d", fc->name, bch->nr, count,
+			 bch->tx_idx, bch->tx_skb->len);
+		bch->tx_idx += count;
+	} else {
+		pr_debug("%s.B%d: fillempty %d\n", fc->name, bch->nr, count);
+	}
 	hdlc->ctrl.sr.xml = ((count == fs) ? 0 : count);
 	if (fc->type == AVM_FRITZ_PCIV2) {
 		__write_ctrl_pciv2(fc, hdlc, bch->nr);
@@ -475,13 +486,21 @@ hdlc_fill_fifo(struct bchannel *bch)
 		__write_ctrl_pci(fc, hdlc, bch->nr);
 		addr = fc->addr + CHIP_WINDOW;
 	}
-	while (cnt < count) {
-		val = get_unaligned(ptr);
-		outl(cpu_to_le32(val), addr);
-		ptr++;
-		cnt += 4;
+	if (fillempty) {
+		while (cnt < count) {
+			/* all bytes the same - no worry about endian */
+			outl(*ptr, addr);
+			cnt += 4;
+		}
+	} else {
+		while (cnt < count) {
+			val = get_unaligned(ptr);
+			outl(cpu_to_le32(val), addr);
+			ptr++;
+			cnt += 4;
+		}
 	}
-	if (debug & DEBUG_HW_BFIFO) {
+	if ((debug & DEBUG_HW_BFIFO) && !fillempty) {
 		snprintf(fc->log, LOG_SIZE, "B%1d-send %s %d ",
 			 bch->nr, fc->name, count);
 		print_hex_dump_bytes(fc->log, DUMP_PREFIX_OFFSET, p, count);
@@ -496,8 +515,12 @@ HDLC_irq_xpr(struct bchannel *bch)
 	} else {
 		if (bch->tx_skb)
 			dev_kfree_skb(bch->tx_skb);
-		if (get_next_bframe(bch))
+		if (get_next_bframe(bch)) {
 			hdlc_fill_fifo(bch);
+			test_and_clear_bit(FLG_TX_EMPTY, &bch->Flags);
+		} else if (test_bit(FLG_TX_EMPTY, &bch->Flags)) {
+			hdlc_fill_fifo(bch);
+		}
 	}
 }
 
@@ -561,6 +584,8 @@ handle_tx:
 		if (bch->tx_skb && bch->tx_skb->len) {
 			if (!test_bit(FLG_TRANSPARENT, &bch->Flags))
 				bch->tx_idx = 0;
+		} else if (test_bit(FLG_FILLEMPTY, &bch->Flags)) {
+			test_and_set_bit(FLG_TX_EMPTY, &bch->Flags);
 		}
 		hdlc->ctrl.sr.xml = 0;
 		hdlc->ctrl.sr.cmd |= HDLC_CMD_XRS;
@@ -882,7 +907,6 @@ open_bchannel(struct fritzcard *fc, struct channel_req *rq)
 	bch = &fc->bch[rq->adr.channel - 1];
 	if (test_and_set_bit(FLG_OPEN, &bch->Flags))
 		return -EBUSY; /* b-channel can be only open once */
-	test_and_clear_bit(FLG_FILLEMPTY, &bch->Flags);
 	bch->ch.protocol = rq->protocol;
 	rq->ch = &bch->ch;
 	return 0;
diff --git a/drivers/isdn/hardware/mISDN/hfcmulti.c b/drivers/isdn/hardware/mISDN/hfcmulti.c
index 3d4b36d..db9b045 100644
--- a/drivers/isdn/hardware/mISDN/hfcmulti.c
+++ b/drivers/isdn/hardware/mISDN/hfcmulti.c
@@ -3576,7 +3576,7 @@ channel_bctrl(struct bchannel *bch, struct mISDN_ctrl_req *cq)
 	case MISDN_CTRL_GETOP:
 		ret = mISDN_ctrl_bchannel(bch, cq);
 		cq->op |= MISDN_CTRL_HFC_OP | MISDN_CTRL_HW_FEATURES_OP |
-			  MISDN_CTRL_RX_OFF | MISDN_CTRL_FILL_EMPTY;
+			  MISDN_CTRL_RX_OFF;
 		break;
 	case MISDN_CTRL_RX_OFF: /* turn off / on rx stream */
 		hc->chan[bch->slot].rx_off = !!cq->p1;
@@ -3591,11 +3591,10 @@ channel_bctrl(struct bchannel *bch, struct mISDN_ctrl_req *cq)
 			printk(KERN_DEBUG "%s: RX_OFF request (nr=%d off=%d)\n",
 			       __func__, bch->nr, hc->chan[bch->slot].rx_off);
 		break;
-	case MISDN_CTRL_FILL_EMPTY: /* fill fifo, if empty */
-		test_and_set_bit(FLG_FILLEMPTY, &bch->Flags);
-		if (debug & DEBUG_HFCMULTI_MSG)
-			printk(KERN_DEBUG "%s: FILL_EMPTY request (nr=%d "
-			       "off=%d)\n", __func__, bch->nr, !!cq->p1);
+	case MISDN_CTRL_FILL_EMPTY:
+		ret = mISDN_ctrl_bchannel(bch, cq);
+		hc->silence = bch->fill[0];
+		memset(hc->silence_data, hc->silence, sizeof(hc->silence_data));
 		break;
 	case MISDN_CTRL_HW_FEATURES: /* fill features structure */
 		if (debug & DEBUG_HFCMULTI_MSG)
@@ -4118,7 +4117,6 @@ open_bchannel(struct hfc_multi *hc, struct dchannel *dch,
 	}
 	if (test_and_set_bit(FLG_OPEN, &bch->Flags))
 		return -EBUSY; /* b-channel can be only open once */
-	test_and_clear_bit(FLG_FILLEMPTY, &bch->Flags);
 	bch->ch.protocol = rq->protocol;
 	hc->chan[ch].rx_off = 0;
 	rq->ch = &bch->ch;
diff --git a/drivers/isdn/hardware/mISDN/hfcpci.c b/drivers/isdn/hardware/mISDN/hfcpci.c
index 2774375..1bd8bc7 100644
--- a/drivers/isdn/hardware/mISDN/hfcpci.c
+++ b/drivers/isdn/hardware/mISDN/hfcpci.c
@@ -565,11 +565,6 @@ hfcpci_empty_fifo_trans(struct bchannel *bch, struct bzfifo *rxbz,
 	if (new_z2 >= (B_FIFO_SIZE + B_SUB_VAL))
 		new_z2 -= B_FIFO_SIZE;	/* buffer wrap */
 
-	if (fcnt_rx > MAX_DATA_SIZE) {	/* flush, if oversized */
-		*z2r = cpu_to_le16(new_z2);		/* new position */
-		return;
-	}
-
 	fcnt_tx = le16_to_cpu(*z2t) - le16_to_cpu(*z1t);
 	if (fcnt_tx <= 0)
 		fcnt_tx += B_FIFO_SIZE;
@@ -761,9 +756,14 @@ hfcpci_fill_fifo(struct bchannel *bch)
 
 	if ((bch->debug & DEBUG_HW_BCHANNEL) && !(bch->debug & DEBUG_HW_BFIFO))
 		printk(KERN_DEBUG "%s\n", __func__);
-	if ((!bch->tx_skb) || bch->tx_skb->len <= 0)
-		return;
-	count = bch->tx_skb->len - bch->tx_idx;
+	if ((!bch->tx_skb) || bch->tx_skb->len == 0) {
+		if (!test_bit(FLG_FILLEMPTY, &bch->Flags) &&
+		    !test_bit(FLG_TRANSPARENT, &bch->Flags))
+			return;
+		count = HFCPCI_FILLEMPTY;
+	} else {
+		count = bch->tx_skb->len - bch->tx_idx;
+	}
 	if ((bch->nr & 2) && (!hc->hw.bswapped)) {
 		bz = &((union fifo_area *)(hc->hw.fifos))->b_chans.txbz_b2;
 		bdata = ((union fifo_area *)(hc->hw.fifos))->b_chans.txdat_b2;
@@ -782,16 +782,10 @@ hfcpci_fill_fifo(struct bchannel *bch)
 		fcnt = le16_to_cpu(*z2t) - le16_to_cpu(*z1t);
 		if (fcnt <= 0)
 			fcnt += B_FIFO_SIZE;
-		/* fcnt contains available bytes in fifo */
-		fcnt = B_FIFO_SIZE - fcnt;
-		/* remaining bytes to send (bytes in fifo) */
-
-		/* "fill fifo if empty" feature */
-		if (test_bit(FLG_FILLEMPTY, &bch->Flags) && !fcnt) {
-			/* printk(KERN_DEBUG "%s: buffer empty, so we have "
-			   "underrun\n", __func__); */
-			/* fill buffer, to prevent future underrun */
-			count = HFCPCI_FILLEMPTY;
+		if (test_bit(FLG_FILLEMPTY, &bch->Flags)) {
+			/* fcnt contains available bytes in fifo */
+			if (count > fcnt)
+				count = fcnt;
 			new_z1 = le16_to_cpu(*z1t) + count;
 			/* new buffer Position */
 			if (new_z1 >= (B_FIFO_SIZE + B_SUB_VAL))
@@ -803,17 +797,20 @@ hfcpci_fill_fifo(struct bchannel *bch)
 				printk(KERN_DEBUG "hfcpci_FFt fillempty "
 				       "fcnt(%d) maxl(%d) nz1(%x) dst(%p)\n",
 				       fcnt, maxlen, new_z1, dst);
-			fcnt += count;
 			if (maxlen > count)
 				maxlen = count;		/* limit size */
-			memset(dst, 0x2a, maxlen);	/* first copy */
+			memset(dst, bch->fill[0], maxlen); /* first copy */
 			count -= maxlen;		/* remaining bytes */
 			if (count) {
 				dst = bdata;		/* start of buffer */
-				memset(dst, 0x2a, count);
+				memset(dst, bch->fill[0], count);
 			}
 			*z1t = cpu_to_le16(new_z1);	/* now send data */
+			return;
 		}
+		/* fcnt contains available bytes in fifo */
+		fcnt = B_FIFO_SIZE - fcnt;
+		/* remaining bytes to send (bytes in fifo) */
 
 	next_t_frame:
 		count = bch->tx_skb->len - bch->tx_idx;
@@ -1531,24 +1528,7 @@ deactivate_bchannel(struct bchannel *bch)
 static int
 channel_bctrl(struct bchannel *bch, struct mISDN_ctrl_req *cq)
 {
-	int	ret = 0;
-
-	switch (cq->op) {
-	case MISDN_CTRL_GETOP:
-		ret = mISDN_ctrl_bchannel(bch, cq);
-		cq->op |= MISDN_CTRL_FILL_EMPTY;
-		break;
-	case MISDN_CTRL_FILL_EMPTY: /* fill fifo, if empty */
-		test_and_set_bit(FLG_FILLEMPTY, &bch->Flags);
-		if (debug & DEBUG_HW_OPEN)
-			printk(KERN_DEBUG "%s: FILL_EMPTY request (nr=%d "
-			       "off=%d)\n", __func__, bch->nr, !!cq->p1);
-		break;
-	default:
-		ret = mISDN_ctrl_bchannel(bch, cq);
-		break;
-	}
-	return ret;
+	return mISDN_ctrl_bchannel(bch, cq);
 }
 static int
 hfc_bctrl(struct mISDNchannel *ch, u_int cmd, void *arg)
@@ -1964,7 +1944,6 @@ open_bchannel(struct hfc_pci *hc, struct channel_req *rq)
 	bch = &hc->bch[rq->adr.channel - 1];
 	if (test_and_set_bit(FLG_OPEN, &bch->Flags))
 		return -EBUSY; /* b-channel can be only open once */
-	test_and_clear_bit(FLG_FILLEMPTY, &bch->Flags);
 	bch->ch.protocol = rq->protocol;
 	rq->ch = &bch->ch; /* TODO: E-channel */
 	if (!try_module_get(THIS_MODULE))
diff --git a/drivers/isdn/hardware/mISDN/hfcsusb.c b/drivers/isdn/hardware/mISDN/hfcsusb.c
index 9c17473..b539b10 100644
--- a/drivers/isdn/hardware/mISDN/hfcsusb.c
+++ b/drivers/isdn/hardware/mISDN/hfcsusb.c
@@ -491,7 +491,6 @@ open_bchannel(struct hfcsusb *hw, struct channel_req *rq)
 	bch = &hw->bch[rq->adr.channel - 1];
 	if (test_and_set_bit(FLG_OPEN, &bch->Flags))
 		return -EBUSY; /* b-channel can be only open once */
-	test_and_clear_bit(FLG_FILLEMPTY, &bch->Flags);
 	bch->ch.protocol = rq->protocol;
 	rq->ch = &bch->ch;
 
@@ -806,24 +805,7 @@ hfcsusb_ph_command(struct hfcsusb *hw, u_char command)
 static int
 channel_bctrl(struct bchannel *bch, struct mISDN_ctrl_req *cq)
 {
-	int	ret = 0;
-
-	switch (cq->op) {
-	case MISDN_CTRL_GETOP:
-		ret = mISDN_ctrl_bchannel(bch, cq);
-		cq->op |= MISDN_CTRL_FILL_EMPTY;
-		break;
-	case MISDN_CTRL_FILL_EMPTY: /* fill fifo, if empty */
-		test_and_set_bit(FLG_FILLEMPTY, &bch->Flags);
-		if (debug & DEBUG_HW_OPEN)
-			printk(KERN_DEBUG "%s: FILL_EMPTY request (nr=%d "
-			       "off=%d)\n", __func__, bch->nr, !!cq->p1);
-		break;
-	default:
-		ret = mISDN_ctrl_bchannel(bch, cq);
-		break;
-	}
-	return ret;
+	return mISDN_ctrl_bchannel(bch, cq);
 }
 
 /* collect data from incoming interrupt or isochron USB data */
@@ -1183,8 +1165,8 @@ tx_iso_complete(struct urb *urb)
 	int k, tx_offset, num_isoc_packets, sink, remain, current_len,
 		errcode, hdlc, i;
 	int *tx_idx;
-	int frame_complete, fifon, status;
-	__u8 threshbit;
+	int frame_complete, fifon, status, fillempty = 0;
+	__u8 threshbit, *p;
 
 	spin_lock(&hw->lock);
 	if (fifo->stop_gracefull) {
@@ -1202,6 +1184,9 @@ tx_iso_complete(struct urb *urb)
 		tx_skb = fifo->bch->tx_skb;
 		tx_idx = &fifo->bch->tx_idx;
 		hdlc = test_bit(FLG_HDLC, &fifo->bch->Flags);
+		if (!tx_skb && !hdlc &&
+		    test_bit(FLG_FILLEMPTY, &fifo->bch->Flags))
+			fillempty = 1;
 	} else {
 		printk(KERN_DEBUG "%s: %s: neither BCH nor DCH\n",
 		       hw->name, __func__);
@@ -1260,6 +1245,8 @@ tx_iso_complete(struct urb *urb)
 			/* Generate next ISO Packets */
 			if (tx_skb)
 				remain = tx_skb->len - *tx_idx;
+			else if (fillempty)
+				remain = 15; /* > not complete */
 			else
 				remain = 0;
 
@@ -1290,15 +1277,20 @@ tx_iso_complete(struct urb *urb)
 				}
 
 				/* copy tx data to iso-urb buffer */
-				memcpy(context_iso_urb->buffer + tx_offset + 1,
-				       (tx_skb->data + *tx_idx), current_len);
-				*tx_idx += current_len;
-
+				p = context_iso_urb->buffer + tx_offset + 1;
+				if (fillempty) {
+					memset(p, fifo->bch->fill[0],
+					       current_len);
+				} else {
+					memcpy(p, (tx_skb->data + *tx_idx),
+					       current_len);
+					*tx_idx += current_len;
+				}
 				urb->iso_frame_desc[k].offset = tx_offset;
 				urb->iso_frame_desc[k].length = current_len + 1;
 
 				/* USB data log for every D ISO out */
-				if ((fifon == HFCUSB_D_RX) &&
+				if ((fifon == HFCUSB_D_RX) && !fillempty &&
 				    (debug & DBG_HFC_USB_VERBOSE)) {
 					printk(KERN_DEBUG
 					       "%s: %s (%d/%d) offs(%d) len(%d) ",
diff --git a/drivers/isdn/hardware/mISDN/mISDNipac.c b/drivers/isdn/hardware/mISDN/mISDNipac.c
index 3e71a5e..374a177 100644
--- a/drivers/isdn/hardware/mISDN/mISDNipac.c
+++ b/drivers/isdn/hardware/mISDN/mISDNipac.c
@@ -969,22 +969,28 @@ hscx_fill_fifo(struct hscx_hw *hscx)
 	int count, more;
 	u8 *p;
 
-	if (!hscx->bch.tx_skb)
-		return;
-	count = hscx->bch.tx_skb->len - hscx->bch.tx_idx;
-	if (count <= 0)
-		return;
-	p = hscx->bch.tx_skb->data + hscx->bch.tx_idx;
-
-	more = test_bit(FLG_TRANSPARENT, &hscx->bch.Flags) ? 1 : 0;
-	if (count > hscx->fifo_size) {
+	if (!hscx->bch.tx_skb) {
+		if (!test_bit(FLG_TX_EMPTY, &hscx->bch.Flags))
+			return;
 		count = hscx->fifo_size;
 		more = 1;
-	}
-	pr_debug("%s: B%1d %d/%d/%d\n", hscx->ip->name, hscx->bch.nr, count,
-		 hscx->bch.tx_idx, hscx->bch.tx_skb->len);
-	hscx->bch.tx_idx += count;
+		p = hscx->log;
+		memset(p, hscx->bch.fill[0], count);
+	} else {
+		count = hscx->bch.tx_skb->len - hscx->bch.tx_idx;
+		if (count <= 0)
+			return;
+		p = hscx->bch.tx_skb->data + hscx->bch.tx_idx;
 
+		more = test_bit(FLG_TRANSPARENT, &hscx->bch.Flags) ? 1 : 0;
+		if (count > hscx->fifo_size) {
+			count = hscx->fifo_size;
+			more = 1;
+		}
+		pr_debug("%s: B%1d %d/%d/%d\n", hscx->ip->name, hscx->bch.nr,
+			 count, hscx->bch.tx_idx, hscx->bch.tx_skb->len);
+		hscx->bch.tx_idx += count;
+	}
 	if (hscx->ip->type & IPAC_TYPE_IPACX)
 		hscx->ip->write_fifo(hscx->ip->hw,
 				     hscx->off + IPACX_XFIFOB, p, count);
@@ -995,7 +1001,7 @@ hscx_fill_fifo(struct hscx_hw *hscx)
 	}
 	hscx_cmdr(hscx, more ? 0x08 : 0x0a);
 
-	if (hscx->bch.debug & DEBUG_HW_BFIFO) {
+	if (hscx->bch.tx_skb && (hscx->bch.debug & DEBUG_HW_BFIFO)) {
 		snprintf(hscx->log, 64, "B%1d-send %s %d ",
 			 hscx->bch.nr, hscx->ip->name, count);
 		print_hex_dump_bytes(hscx->log, DUMP_PREFIX_OFFSET, p, count);
@@ -1010,8 +1016,12 @@ hscx_xpr(struct hscx_hw *hx)
 	} else {
 		if (hx->bch.tx_skb)
 			dev_kfree_skb(hx->bch.tx_skb);
-		if (get_next_bframe(&hx->bch))
+		if (get_next_bframe(&hx->bch)) {
 			hscx_fill_fifo(hx);
+			test_and_clear_bit(FLG_TX_EMPTY, &hx->bch.Flags);
+		} else if (test_bit(FLG_TX_EMPTY, &hx->bch.Flags)) {
+			hscx_fill_fifo(hx);
+		}
 	}
 }
 
@@ -1128,7 +1138,9 @@ ipac_irq(struct hscx_hw *hx, u8 ista)
 
 	if (istab & IPACX_B_XDU) {
 		if (test_bit(FLG_TRANSPARENT, &hx->bch.Flags)) {
-			hscx_fill_fifo(hx);
+			if (test_bit(FLG_FILLEMPTY, &hx->bch.Flags))
+				test_and_set_bit(FLG_TX_EMPTY, &hx->bch.Flags);
+			hscx_xpr(hx);
 			return;
 		}
 		pr_debug("%s: B%1d XDU error at len %d\n", hx->ip->name,
diff --git a/drivers/isdn/hardware/mISDN/mISDNisar.c b/drivers/isdn/hardware/mISDN/mISDNisar.c
index e74ad38..901be32 100644
--- a/drivers/isdn/hardware/mISDN/mISDNisar.c
+++ b/drivers/isdn/hardware/mISDN/mISDNisar.c
@@ -585,16 +585,25 @@ isar_fill_fifo(struct isar_ch *ch)
 	u8 msb;
 	u8 *ptr;
 
-	pr_debug("%s: ch%d  tx_skb %p tx_idx %d\n",
-		 ch->is->name, ch->bch.nr, ch->bch.tx_skb, ch->bch.tx_idx);
-	if (!ch->bch.tx_skb)
+	pr_debug("%s: ch%d  tx_skb %d tx_idx %d\n", ch->is->name, ch->bch.nr,
+		 ch->bch.tx_skb ? ch->bch.tx_skb->len : -1, ch->bch.tx_idx);
+	if (!(ch->is->bstat &
+	      (ch->dpath == 1 ? BSTAT_RDM1 : BSTAT_RDM2)))
+		return;
+	if (!ch->bch.tx_skb) {
+		if (!test_bit(FLG_TX_EMPTY, &ch->bch.Flags) ||
+		    (ch->bch.state != ISDN_P_B_RAW))
+			return;
+		count = ch->mml;
+		/* use the card buffer */
+		memset(ch->is->buf, ch->bch.fill[0], count);
+		send_mbox(ch->is, SET_DPS(ch->dpath) | ISAR_HIS_SDATA,
+			  0, count, ch->is->buf);
 		return;
+	}
 	count = ch->bch.tx_skb->len - ch->bch.tx_idx;
 	if (count <= 0)
 		return;
-	if (!(ch->is->bstat &
-	      (ch->dpath == 1 ? BSTAT_RDM1 : BSTAT_RDM2)))
-		return;
 	if (count > ch->mml) {
 		msb = 0;
 		count = ch->mml;
@@ -673,9 +682,9 @@ sel_bch_isar(struct isar_hw *isar, u8 dpath)
 static void
 send_next(struct isar_ch *ch)
 {
-	pr_debug("%s: %s ch%d tx_skb %p tx_idx %d\n",
-		 ch->is->name, __func__, ch->bch.nr,
-		 ch->bch.tx_skb, ch->bch.tx_idx);
+	pr_debug("%s: %s ch%d tx_skb %d tx_idx %d\n", ch->is->name, __func__,
+		 ch->bch.nr, ch->bch.tx_skb ? ch->bch.tx_skb->len : -1,
+		 ch->bch.tx_idx);
 	if (ch->bch.state == ISDN_P_B_T30_FAX) {
 		if (ch->cmd == PCTRL_CMD_FTH) {
 			if (test_bit(FLG_LASTDATA, &ch->bch.Flags)) {
@@ -693,6 +702,9 @@ send_next(struct isar_ch *ch)
 		dev_kfree_skb(ch->bch.tx_skb);
 	if (get_next_bframe(&ch->bch)) {
 		isar_fill_fifo(ch);
+		test_and_clear_bit(FLG_TX_EMPTY, &ch->bch.Flags);
+	} else if (test_bit(FLG_TX_EMPTY, &ch->bch.Flags)) {
+		isar_fill_fifo(ch);
 	} else {
 		if (test_and_clear_bit(FLG_DLEETX, &ch->bch.Flags)) {
 			if (test_and_clear_bit(FLG_LASTDATA,
@@ -707,6 +719,8 @@ send_next(struct isar_ch *ch)
 			} else {
 				deliver_status(ch, HW_MOD_CONNECT);
 			}
+		} else if (test_bit(FLG_FILLEMPTY, &ch->bch.Flags)) {
+			test_and_set_bit(FLG_TX_EMPTY, &ch->bch.Flags);
 		}
 	}
 }
@@ -1638,7 +1652,6 @@ isar_open(struct isar_hw *isar, struct channel_req *rq)
 	bch = &isar->ch[rq->adr.channel - 1].bch;
 	if (test_and_set_bit(FLG_OPEN, &bch->Flags))
 		return -EBUSY; /* b-channel can be only open once */
-	test_and_clear_bit(FLG_FILLEMPTY, &bch->Flags);
 	bch->ch.protocol = rq->protocol;
 	rq->ch = &bch->ch;
 	return 0;
diff --git a/drivers/isdn/hardware/mISDN/netjet.c b/drivers/isdn/hardware/mISDN/netjet.c
index 47d3074..aa95cc7 100644
--- a/drivers/isdn/hardware/mISDN/netjet.c
+++ b/drivers/isdn/hardware/mISDN/netjet.c
@@ -533,22 +533,31 @@ static void
 fill_dma(struct tiger_ch *bc)
 {
 	struct tiger_hw *card = bc->bch.hw;
-	int count, i;
-	u32 m, v;
+	int count, i, fillempty = 0;
+	u32 m, v, n = 0;
 	u8  *p;
 
 	if (bc->free == 0)
 		return;
-	count = bc->bch.tx_skb->len - bc->bch.tx_idx;
-	if (count <= 0)
-		return;
-	pr_debug("%s: %s B%1d %d/%d/%d/%d state %x idx %d/%d\n", card->name,
-		 __func__, bc->bch.nr, count, bc->free, bc->bch.tx_idx,
-		 bc->bch.tx_skb->len, bc->txstate, bc->idx, card->send.idx);
+	if (!bc->bch.tx_skb) {
+		if (!test_bit(FLG_TX_EMPTY, &bc->bch.Flags))
+			return;
+		fillempty = 1;
+		count = card->send.size >> 1;
+		p = bc->bch.fill;
+	} else {
+		count = bc->bch.tx_skb->len - bc->bch.tx_idx;
+		if (count <= 0)
+			return;
+		pr_debug("%s: %s B%1d %d/%d/%d/%d state %x idx %d/%d\n",
+			 card->name, __func__, bc->bch.nr, count, bc->free,
+			 bc->bch.tx_idx, bc->bch.tx_skb->len, bc->txstate,
+			 bc->idx, card->send.idx);
+		p = bc->bch.tx_skb->data + bc->bch.tx_idx;
+	}
 	if (bc->txstate & (TX_IDLE | TX_INIT | TX_UNDERRUN))
 		resync(bc, card);
-	p = bc->bch.tx_skb->data + bc->bch.tx_idx;
-	if (test_bit(FLG_HDLC, &bc->bch.Flags)) {
+	if (test_bit(FLG_HDLC, &bc->bch.Flags) && !fillempty) {
 		count = isdnhdlc_encode(&bc->hsend, p, count, &i,
 					bc->hsbuf, bc->free);
 		pr_debug("%s: B%1d hdlc encoded %d in %d\n", card->name,
@@ -559,17 +568,33 @@ fill_dma(struct tiger_ch *bc)
 	} else {
 		if (count > bc->free)
 			count = bc->free;
-		bc->bch.tx_idx += count;
+		if (!fillempty)
+			bc->bch.tx_idx += count;
 		bc->free -= count;
 	}
 	m = (bc->bch.nr & 1) ? 0xffffff00 : 0xffff00ff;
-	for (i = 0; i < count; i++) {
-		if (bc->idx >= card->send.size)
-			bc->idx = 0;
-		v = card->send.start[bc->idx];
-		v &= m;
-		v |= (bc->bch.nr & 1) ? (u32)(p[i]) : ((u32)(p[i])) << 8;
-		card->send.start[bc->idx++] = v;
+	if (fillempty) {
+		n = p[0];
+		if (!(bc->bch.nr & 1))
+			n <<= 8;
+		for (i = 0; i < count; i++) {
+			if (bc->idx >= card->send.size)
+				bc->idx = 0;
+			v = card->send.start[bc->idx];
+			v &= m;
+			v |= n;
+			card->send.start[bc->idx++] = v;
+		}
+	} else {
+		for (i = 0; i < count; i++) {
+			if (bc->idx >= card->send.size)
+				bc->idx = 0;
+			v = card->send.start[bc->idx];
+			v &= m;
+			n = p[i];
+			v |= (bc->bch.nr & 1) ? n : n << 8;
+			card->send.start[bc->idx++] = v;
+		}
 	}
 	if (debug & DEBUG_HW_BFIFO) {
 		snprintf(card->log, LOG_SIZE, "B%1d-send %s %d ",
@@ -584,17 +609,26 @@ fill_dma(struct tiger_ch *bc)
 static int
 bc_next_frame(struct tiger_ch *bc)
 {
+	int ret = 1;
+
 	if (bc->bch.tx_skb && bc->bch.tx_idx < bc->bch.tx_skb->len) {
 		fill_dma(bc);
 	} else {
 		if (bc->bch.tx_skb)
 			dev_kfree_skb(bc->bch.tx_skb);
-		if (get_next_bframe(&bc->bch))
+		if (get_next_bframe(&bc->bch)) {
 			fill_dma(bc);
-		else
-			return 0;
+			test_and_clear_bit(FLG_TX_EMPTY, &bc->bch.Flags);
+		} else if (test_bit(FLG_TX_EMPTY, &bc->bch.Flags)) {
+			fill_dma(bc);
+		} else if (test_bit(FLG_FILLEMPTY, &bc->bch.Flags)) {
+			test_and_set_bit(FLG_TX_EMPTY, &bc->bch.Flags);
+			ret = 0;
+		} else {
+			ret = 0;
+		}
 	}
-	return 1;
+	return ret;
 }
 
 static void
diff --git a/drivers/isdn/hardware/mISDN/w6692.c b/drivers/isdn/hardware/mISDN/w6692.c
index 03fb4a3..183181f 100644
--- a/drivers/isdn/hardware/mISDN/w6692.c
+++ b/drivers/isdn/hardware/mISDN/w6692.c
@@ -498,16 +498,22 @@ static void
 W6692_fill_Bfifo(struct w6692_ch *wch)
 {
 	struct w6692_hw *card = wch->bch.hw;
-	int count;
+	int count, fillempty = 0;
 	u8 *ptr, cmd = W_B_CMDR_RACT | W_B_CMDR_XMS;
 
 	pr_debug("%s: fill Bfifo\n", card->name);
-	if (!wch->bch.tx_skb)
-		return;
-	count = wch->bch.tx_skb->len - wch->bch.tx_idx;
-	if (count <= 0)
-		return;
-	ptr = wch->bch.tx_skb->data + wch->bch.tx_idx;
+	if (!wch->bch.tx_skb) {
+		if (!test_bit(FLG_TX_EMPTY, &wch->bch.Flags))
+			return;
+		ptr = wch->bch.fill;
+		count = W_B_FIFO_THRESH;
+		fillempty = 1;
+	} else {
+		count = wch->bch.tx_skb->len - wch->bch.tx_idx;
+		if (count <= 0)
+			return;
+		ptr = wch->bch.tx_skb->data + wch->bch.tx_idx;
+	}
 	if (count > W_B_FIFO_THRESH)
 		count = W_B_FIFO_THRESH;
 	else if (test_bit(FLG_HDLC, &wch->bch.Flags))
@@ -516,9 +522,16 @@ W6692_fill_Bfifo(struct w6692_ch *wch)
 	pr_debug("%s: fill Bfifo%d/%d\n", card->name,
 		 count, wch->bch.tx_idx);
 	wch->bch.tx_idx += count;
-	outsb(wch->addr + W_B_XFIFO, ptr, count);
+	if (fillempty) {
+		while (count > 0) {
+			outsb(wch->addr + W_B_XFIFO, ptr, MISDN_BCH_FILL_SIZE);
+			count -= MISDN_BCH_FILL_SIZE;
+		}
+	} else {
+		outsb(wch->addr + W_B_XFIFO, ptr, count);
+	}
 	WriteW6692B(wch, W_B_CMDR, cmd);
-	if (debug & DEBUG_HW_DFIFO) {
+	if ((debug & DEBUG_HW_BFIFO) && !fillempty) {
 		snprintf(card->log, 63, "B%1d-send %s %d ",
 			 wch->bch.nr, card->name, count);
 		print_hex_dump_bytes(card->log, DUMP_PREFIX_OFFSET, ptr, count);
@@ -637,8 +650,12 @@ send_next(struct w6692_ch *wch)
 	} else {
 		if (wch->bch.tx_skb)
 			dev_kfree_skb(wch->bch.tx_skb);
-		if (get_next_bframe(&wch->bch))
+		if (get_next_bframe(&wch->bch)) {
+			W6692_fill_Bfifo(wch);
+			test_and_clear_bit(FLG_TX_EMPTY, &wch->bch.Flags);
+		} else if (test_bit(FLG_TX_EMPTY, &wch->bch.Flags)) {
 			W6692_fill_Bfifo(wch);
+		}
 	}
 }
 
@@ -727,8 +744,8 @@ W6692B_interrupt(struct w6692_hw *card, int ch)
 				 wch->bch.nr, star);
 		}
 		if (star & W_B_STAR_XDOW) {
-			pr_debug("%s: B%d XDOW proto=%x\n", card->name,
-				 wch->bch.nr, wch->bch.state);
+			pr_warning("%s: B%d XDOW proto=%x\n", card->name,
+				   wch->bch.nr, wch->bch.state);
 #ifdef ERROR_STATISTIC
 			wch->bch.err_xdu++;
 #endif
@@ -741,20 +758,21 @@ W6692B_interrupt(struct w6692_hw *card, int ch)
 			}
 		}
 		send_next(wch);
-		if (stat & W_B_EXI_XDUN)
+		if (star & W_B_STAR_XDOW)
 			return; /* handle XDOW only once */
 	}
 	if (stat & W_B_EXI_XDUN) {
-		pr_debug("%s: B%d XDUN proto=%x\n", card->name,
-			 wch->bch.nr, wch->bch.state);
+		pr_warning("%s: B%d XDUN proto=%x\n", card->name,
+			   wch->bch.nr, wch->bch.state);
 #ifdef ERROR_STATISTIC
 		wch->bch.err_xdu++;
 #endif
-		WriteW6692B(wch, W_B_CMDR, W_B_CMDR_XRST | W_B_CMDR_RACT);
-		/* resend */
+		/* resend - no XRST needed */
 		if (wch->bch.tx_skb) {
 			if (!test_bit(FLG_TRANSPARENT, &wch->bch.Flags))
 				wch->bch.tx_idx = 0;
+		} else if (test_bit(FLG_FILLEMPTY, &wch->bch.Flags)) {
+			test_and_set_bit(FLG_TX_EMPTY, &wch->bch.Flags);
 		}
 		send_next(wch);
 	}
@@ -993,7 +1011,6 @@ open_bchannel(struct w6692_hw *card, struct channel_req *rq)
 	bch = &card->bc[rq->adr.channel - 1].bch;
 	if (test_and_set_bit(FLG_OPEN, &bch->Flags))
 		return -EBUSY; /* b-channel can be only open once */
-	test_and_clear_bit(FLG_FILLEMPTY, &bch->Flags);
 	bch->ch.protocol = rq->protocol;
 	rq->ch = &bch->ch;
 	return 0;
diff --git a/drivers/isdn/mISDN/dsp_core.c b/drivers/isdn/mISDN/dsp_core.c
index 2ac2d7a..28c99c6 100644
--- a/drivers/isdn/mISDN/dsp_core.c
+++ b/drivers/isdn/mISDN/dsp_core.c
@@ -268,6 +268,7 @@ dsp_fill_empty(struct dsp *dsp)
 	}
 	cq.op = MISDN_CTRL_FILL_EMPTY;
 	cq.p1 = 1;
+	cq.p2 = dsp_silence;
 	if (dsp->ch.peer->ctrl(dsp->ch.peer, CONTROL_CHANNEL, &cq)) {
 		printk(KERN_DEBUG "%s: CONTROL_CHANNEL failed\n",
 		       __func__);
diff --git a/drivers/isdn/mISDN/hwchannel.c b/drivers/isdn/mISDN/hwchannel.c
index d42ad0e..e541b65 100644
--- a/drivers/isdn/mISDN/hwchannel.c
+++ b/drivers/isdn/mISDN/hwchannel.c
@@ -140,6 +140,8 @@ mISDN_clear_bchannel(struct bchannel *ch)
 	test_and_clear_bit(FLG_TX_BUSY, &ch->Flags);
 	test_and_clear_bit(FLG_TX_NEXT, &ch->Flags);
 	test_and_clear_bit(FLG_ACTIVE, &ch->Flags);
+	test_and_clear_bit(FLG_FILLEMPTY, &ch->Flags);
+	test_and_clear_bit(FLG_TX_EMPTY, &ch->Flags);
 	ch->minlen = ch->init_minlen;
 	ch->next_minlen = ch->init_minlen;
 	ch->maxlen = ch->init_maxlen;
@@ -165,7 +167,15 @@ mISDN_ctrl_bchannel(struct bchannel *bch, struct mISDN_ctrl_req *cq)
 
 	switch (cq->op) {
 	case MISDN_CTRL_GETOP:
-		cq->op = MISDN_CTRL_RX_BUFFER;
+		cq->op = MISDN_CTRL_RX_BUFFER | MISDN_CTRL_FILL_EMPTY;
+		break;
+	case MISDN_CTRL_FILL_EMPTY:
+		if (cq->p1) {
+			memset(bch->fill, cq->p2 & 0xff, MISDN_BCH_FILL_SIZE);
+			test_and_set_bit(FLG_FILLEMPTY, &bch->Flags);
+		} else {
+			test_and_clear_bit(FLG_FILLEMPTY, &bch->Flags);
+		}
 		break;
 	case MISDN_CTRL_RX_BUFFER:
 		if (cq->p2 > MISDN_CTRL_RX_SIZE_IGNORE)