mISDN: Allow to set a minimum length for transparent data

If the FIFO of the card is small, many short messages are queued up to
the upper layers and the userspace. This change allows the applications
to set a minimum datalen they want from the drivers.
Create a common control function to avoid code duplication in each
driver.

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

12 files changed, 135 insertions, 132 deletions

diff --git a/drivers/isdn/hardware/mISDN/avmfritz.c b/drivers/isdn/hardware/mISDN/avmfritz.c
index 8081367..7cd3a96 100644
--- a/drivers/isdn/hardware/mISDN/avmfritz.c
+++ b/drivers/isdn/hardware/mISDN/avmfritz.c
@@ -536,12 +536,12 @@ HDLC_irq(struct bchannel *bch, u32 stat)
 			hdlc_empty_fifo(bch, len);
 			if (!bch->rx_skb)
 				goto handle_tx;
-			if (test_bit(FLG_TRANSPARENT, &bch->Flags) ||
-			    (stat & HDLC_STAT_RME)) {
-				if (((stat & HDLC_STAT_CRCVFRRAB) ==
-				     HDLC_STAT_CRCVFR) ||
-				    test_bit(FLG_TRANSPARENT, &bch->Flags)) {
-					recv_Bchannel(bch, 0);
+			if (test_bit(FLG_TRANSPARENT, &bch->Flags)) {
+				recv_Bchannel(bch, 0, false);
+			} else if (stat & HDLC_STAT_RME) {
+				if ((stat & HDLC_STAT_CRCVFRRAB) ==
+				    HDLC_STAT_CRCVFR) {
+					recv_Bchannel(bch, 0, false);
 				} else {
 					pr_warning("%s: got invalid frame\n",
 						   fc->name);
@@ -809,21 +809,7 @@ init_card(struct fritzcard *fc)
 static int
 channel_bctrl(struct bchannel *bch, struct mISDN_ctrl_req *cq)
 {
-	int ret = 0;
-	struct fritzcard *fc = bch->hw;
-
-	switch (cq->op) {
-	case MISDN_CTRL_GETOP:
-		cq->op = 0;
-		break;
-		/* Nothing implemented yet */
-	case MISDN_CTRL_FILL_EMPTY:
-	default:
-		pr_info("%s: %s unknown Op %x\n", fc->name, __func__, cq->op);
-		ret = -EINVAL;
-		break;
-	}
-	return ret;
+	return mISDN_ctrl_bchannel(bch, cq);
 }
 
 static int
@@ -1019,6 +1005,7 @@ static int __devinit
 setup_instance(struct fritzcard *card)
 {
 	int i, err;
+	unsigned short minsize;
 	u_long flags;
 
 	snprintf(card->name, MISDN_MAX_IDLEN - 1, "AVM.%d", AVM_cnt + 1);
@@ -1038,7 +1025,11 @@ setup_instance(struct fritzcard *card)
 	for (i = 0; i < 2; i++) {
 		card->bch[i].nr = i + 1;
 		set_channelmap(i + 1, card->isac.dch.dev.channelmap);
-		mISDN_initbchannel(&card->bch[i], MAX_DATA_MEM);
+		if (AVM_FRITZ_PCIV2 == card->type)
+			minsize = HDLC_FIFO_SIZE_V2;
+		else
+			minsize = HDLC_FIFO_SIZE_V1;
+		mISDN_initbchannel(&card->bch[i], MAX_DATA_MEM, minsize);
 		card->bch[i].hw = card;
 		card->bch[i].ch.send = avm_l2l1B;
 		card->bch[i].ch.ctrl = avm_bctrl;
diff --git a/drivers/isdn/hardware/mISDN/hfcmulti.c b/drivers/isdn/hardware/mISDN/hfcmulti.c
index 60dd6ef..3d4b36d 100644
--- a/drivers/isdn/hardware/mISDN/hfcmulti.c
+++ b/drivers/isdn/hardware/mISDN/hfcmulti.c
@@ -2352,7 +2352,7 @@ next_frame:
 			if (dch)
 				recv_Dchannel(dch);
 			else
-				recv_Bchannel(bch, MISDN_ID_ANY);
+				recv_Bchannel(bch, MISDN_ID_ANY, false);
 			*sp = skb;
 			again++;
 			goto next_frame;
@@ -2367,7 +2367,7 @@ next_frame:
 			       "(z1=%04x, z2=%04x) TRANS\n",
 			       __func__, hc->id + 1, ch, Zsize, z1, z2);
 		/* only bch is transparent */
-		recv_Bchannel(bch, hc->chan[ch].Zfill);
+		recv_Bchannel(bch, hc->chan[ch].Zfill, false);
 	}
 }
 
@@ -3574,8 +3574,9 @@ channel_bctrl(struct bchannel *bch, struct mISDN_ctrl_req *cq)
 
 	switch (cq->op) {
 	case MISDN_CTRL_GETOP:
-		cq->op = MISDN_CTRL_HFC_OP | MISDN_CTRL_HW_FEATURES_OP
-			| MISDN_CTRL_RX_OFF | MISDN_CTRL_FILL_EMPTY;
+		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;
 		break;
 	case MISDN_CTRL_RX_OFF: /* turn off / on rx stream */
 		hc->chan[bch->slot].rx_off = !!cq->p1;
@@ -3683,9 +3684,7 @@ channel_bctrl(struct bchannel *bch, struct mISDN_ctrl_req *cq)
 			ret = -EINVAL;
 		break;
 	default:
-		printk(KERN_WARNING "%s: unknown Op %x\n",
-		       __func__, cq->op);
-		ret = -EINVAL;
+		ret = mISDN_ctrl_bchannel(bch, cq);
 		break;
 	}
 	return ret;
@@ -4855,7 +4854,7 @@ init_e1_port(struct hfc_multi *hc, struct hm_map *m, int pt)
 		bch->nr = ch;
 		bch->slot = ch;
 		bch->debug = debug;
-		mISDN_initbchannel(bch, MAX_DATA_MEM);
+		mISDN_initbchannel(bch, MAX_DATA_MEM, poll >> 1);
 		bch->hw = hc;
 		bch->ch.send = handle_bmsg;
 		bch->ch.ctrl = hfcm_bctrl;
@@ -4928,7 +4927,7 @@ init_multi_port(struct hfc_multi *hc, int pt)
 		bch->nr = ch + 1;
 		bch->slot = i + ch;
 		bch->debug = debug;
-		mISDN_initbchannel(bch, MAX_DATA_MEM);
+		mISDN_initbchannel(bch, MAX_DATA_MEM, poll >> 1);
 		bch->hw = hc;
 		bch->ch.send = handle_bmsg;
 		bch->ch.ctrl = hfcm_bctrl;
diff --git a/drivers/isdn/hardware/mISDN/hfcpci.c b/drivers/isdn/hardware/mISDN/hfcpci.c
index 0622e05..2774375 100644
--- a/drivers/isdn/hardware/mISDN/hfcpci.c
+++ b/drivers/isdn/hardware/mISDN/hfcpci.c
@@ -453,7 +453,7 @@ hfcpci_empty_bfifo(struct bchannel *bch, struct bzfifo *bz,
 		}
 		bz->za[new_f2].z2 = cpu_to_le16(new_z2);
 		bz->f2 = new_f2;	/* next buffer */
-		recv_Bchannel(bch, MISDN_ID_ANY);
+		recv_Bchannel(bch, MISDN_ID_ANY, false);
 	}
 }
 
@@ -599,7 +599,7 @@ hfcpci_empty_fifo_trans(struct bchannel *bch, struct bzfifo *rxbz,
 			ptr1 = bdata;	/* start of buffer */
 			memcpy(ptr, ptr1, fcnt_rx);	/* rest */
 		}
-		recv_Bchannel(bch, fcnt_tx); /* bch, id */
+		recv_Bchannel(bch, fcnt_tx, false); /* bch, id, !force */
 	}
 	*z2r = cpu_to_le16(new_z2);		/* new position */
 }
@@ -1535,7 +1535,8 @@ channel_bctrl(struct bchannel *bch, struct mISDN_ctrl_req *cq)
 
 	switch (cq->op) {
 	case MISDN_CTRL_GETOP:
-		cq->op = MISDN_CTRL_FILL_EMPTY;
+		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);
@@ -1544,8 +1545,7 @@ channel_bctrl(struct bchannel *bch, struct mISDN_ctrl_req *cq)
 			       "off=%d)\n", __func__, bch->nr, !!cq->p1);
 		break;
 	default:
-		printk(KERN_WARNING "%s: unknown Op %x\n", __func__, cq->op);
-		ret = -EINVAL;
+		ret = mISDN_ctrl_bchannel(bch, cq);
 		break;
 	}
 	return ret;
@@ -2116,7 +2116,7 @@ setup_card(struct hfc_pci *card)
 		card->bch[i].nr = i + 1;
 		set_channelmap(i + 1, card->dch.dev.channelmap);
 		card->bch[i].debug = debug;
-		mISDN_initbchannel(&card->bch[i], MAX_DATA_MEM);
+		mISDN_initbchannel(&card->bch[i], MAX_DATA_MEM, poll >> 1);
 		card->bch[i].hw = card;
 		card->bch[i].ch.send = hfcpci_l2l1B;
 		card->bch[i].ch.ctrl = hfc_bctrl;
diff --git a/drivers/isdn/hardware/mISDN/hfcsusb.c b/drivers/isdn/hardware/mISDN/hfcsusb.c
index 6bb689b..9c17473 100644
--- a/drivers/isdn/hardware/mISDN/hfcsusb.c
+++ b/drivers/isdn/hardware/mISDN/hfcsusb.c
@@ -810,7 +810,8 @@ channel_bctrl(struct bchannel *bch, struct mISDN_ctrl_req *cq)
 
 	switch (cq->op) {
 	case MISDN_CTRL_GETOP:
-		cq->op = MISDN_CTRL_FILL_EMPTY;
+		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);
@@ -819,8 +820,7 @@ channel_bctrl(struct bchannel *bch, struct mISDN_ctrl_req *cq)
 			       "off=%d)\n", __func__, bch->nr, !!cq->p1);
 		break;
 	default:
-		printk(KERN_WARNING "%s: unknown Op %x\n", __func__, cq->op);
-		ret = -EINVAL;
+		ret = mISDN_ctrl_bchannel(bch, cq);
 		break;
 	}
 	return ret;
@@ -931,7 +931,8 @@ hfcsusb_rx_frame(struct usb_fifo *fifo, __u8 *data, unsigned int len,
 				if (fifo->dch)
 					recv_Dchannel(fifo->dch);
 				if (fifo->bch)
-					recv_Bchannel(fifo->bch, MISDN_ID_ANY);
+					recv_Bchannel(fifo->bch, MISDN_ID_ANY,
+						      0);
 				if (fifo->ech)
 					recv_Echannel(fifo->ech,
 						      &hw->dch);
@@ -952,8 +953,7 @@ hfcsusb_rx_frame(struct usb_fifo *fifo, __u8 *data, unsigned int len,
 		}
 	} else {
 		/* deliver transparent data to layer2 */
-		if (rx_skb->len >= poll)
-			recv_Bchannel(fifo->bch, MISDN_ID_ANY);
+		recv_Bchannel(fifo->bch, MISDN_ID_ANY, false);
 	}
 	spin_unlock(&hw->lock);
 }
@@ -1861,7 +1861,7 @@ setup_instance(struct hfcsusb *hw, struct device *parent)
 		hw->bch[i].nr = i + 1;
 		set_channelmap(i + 1, hw->dch.dev.channelmap);
 		hw->bch[i].debug = debug;
-		mISDN_initbchannel(&hw->bch[i], MAX_DATA_MEM);
+		mISDN_initbchannel(&hw->bch[i], MAX_DATA_MEM, poll >> 1);
 		hw->bch[i].hw = hw;
 		hw->bch[i].ch.send = hfcusb_l2l1B;
 		hw->bch[i].ch.ctrl = hfc_bctrl;
diff --git a/drivers/isdn/hardware/mISDN/mISDNipac.c b/drivers/isdn/hardware/mISDN/mISDNipac.c
index 7d109ed..3e71a5e 100644
--- a/drivers/isdn/hardware/mISDN/mISDNipac.c
+++ b/drivers/isdn/hardware/mISDN/mISDNipac.c
@@ -1063,7 +1063,7 @@ ipac_rme(struct hscx_hw *hx)
 		skb_trim(hx->bch.rx_skb, 0);
 	} else {
 		skb_trim(hx->bch.rx_skb, hx->bch.rx_skb->len - 1);
-		recv_Bchannel(&hx->bch, 0);
+		recv_Bchannel(&hx->bch, 0, false);
 	}
 }
 
@@ -1114,11 +1114,8 @@ ipac_irq(struct hscx_hw *hx, u8 ista)
 
 	if (istab & IPACX_B_RPF) {
 		hscx_empty_fifo(hx, hx->fifo_size);
-		if (test_bit(FLG_TRANSPARENT, &hx->bch.Flags)) {
-			/* receive transparent audio data */
-			if (hx->bch.rx_skb)
-				recv_Bchannel(&hx->bch, 0);
-		}
+		if (test_bit(FLG_TRANSPARENT, &hx->bch.Flags))
+			recv_Bchannel(&hx->bch, 0, false);
 	}
 
 	if (istab & IPACX_B_RFO) {
@@ -1377,20 +1374,7 @@ hscx_l2l1(struct mISDNchannel *ch, struct sk_buff *skb)
 static int
 channel_bctrl(struct bchannel *bch, struct mISDN_ctrl_req *cq)
 {
-	int	ret = 0;
-
-	switch (cq->op) {
-	case MISDN_CTRL_GETOP:
-		cq->op = 0;
-		break;
-		/* Nothing implemented yet */
-	case MISDN_CTRL_FILL_EMPTY:
-	default:
-		pr_info("%s: unknown Op %x\n", __func__, cq->op);
-		ret = -EINVAL;
-		break;
-	}
-	return ret;
+	return mISDN_ctrl_bchannel(bch, cq);
 }
 
 static int
@@ -1608,7 +1592,8 @@ mISDNipac_init(struct ipac_hw *ipac, void *hw)
 		set_channelmap(i + 1, ipac->isac.dch.dev.channelmap);
 		list_add(&ipac->hscx[i].bch.ch.list,
 			 &ipac->isac.dch.dev.bchannels);
-		mISDN_initbchannel(&ipac->hscx[i].bch, MAX_DATA_MEM);
+		mISDN_initbchannel(&ipac->hscx[i].bch, MAX_DATA_MEM,
+				   ipac->hscx[i].fifo_size);
 		ipac->hscx[i].bch.ch.nr = i + 1;
 		ipac->hscx[i].bch.ch.send = &hscx_l2l1;
 		ipac->hscx[i].bch.ch.ctrl = hscx_bctrl;
diff --git a/drivers/isdn/hardware/mISDN/mISDNisar.c b/drivers/isdn/hardware/mISDN/mISDNisar.c
index 4169bb2d..e74ad38 100644
--- a/drivers/isdn/hardware/mISDN/mISDNisar.c
+++ b/drivers/isdn/hardware/mISDN/mISDNisar.c
@@ -446,7 +446,7 @@ isar_rcv_frame(struct isar_ch *ch)
 			break;
 		}
 		rcv_mbox(ch->is, skb_put(ch->bch.rx_skb, ch->is->clsb));
-		recv_Bchannel(&ch->bch, 0);
+		recv_Bchannel(&ch->bch, 0, false);
 		break;
 	case ISDN_P_B_HDLC:
 		maxlen = bchannel_get_rxbuf(&ch->bch, ch->is->clsb);
@@ -481,7 +481,7 @@ isar_rcv_frame(struct isar_ch *ch)
 				break;
 			}
 			skb_trim(ch->bch.rx_skb, ch->bch.rx_skb->len - 2);
-			recv_Bchannel(&ch->bch, 0);
+			recv_Bchannel(&ch->bch, 0, false);
 		}
 		break;
 	case ISDN_P_B_T30_FAX:
@@ -517,7 +517,7 @@ isar_rcv_frame(struct isar_ch *ch)
 				ch->state = STFAX_ESCAPE;
 				/* set_skb_flag(skb, DF_NOMOREDATA); */
 			}
-			recv_Bchannel(&ch->bch, 0);
+			recv_Bchannel(&ch->bch, 0, false);
 			if (ch->is->cmsb & SART_NMD)
 				deliver_status(ch, HW_MOD_NOCARR);
 			break;
@@ -557,7 +557,7 @@ isar_rcv_frame(struct isar_ch *ch)
 				break;
 			}
 			skb_trim(ch->bch.rx_skb, ch->bch.rx_skb->len - 2);
-			recv_Bchannel(&ch->bch, 0);
+			recv_Bchannel(&ch->bch, 0, false);
 		}
 		if (ch->is->cmsb & SART_NMD) { /* ABORT */
 			pr_debug("%s: isar_rcv_frame: no more data\n",
@@ -1554,20 +1554,7 @@ isar_l2l1(struct mISDNchannel *ch, struct sk_buff *skb)
 static int
 channel_bctrl(struct bchannel *bch, struct mISDN_ctrl_req *cq)
 {
-	int	ret = 0;
-
-	switch (cq->op) {
-	case MISDN_CTRL_GETOP:
-		cq->op = 0;
-		break;
-		/* Nothing implemented yet */
-	case MISDN_CTRL_FILL_EMPTY:
-	default:
-		pr_info("%s: unknown Op %x\n", __func__, cq->op);
-		ret = -EINVAL;
-		break;
-	}
-	return ret;
+	return mISDN_ctrl_bchannel(bch, cq);
 }
 
 static int
@@ -1665,7 +1652,7 @@ mISDNisar_init(struct isar_hw *isar, void *hw)
 	isar->hw = hw;
 	for (i = 0; i < 2; i++) {
 		isar->ch[i].bch.nr = i + 1;
-		mISDN_initbchannel(&isar->ch[i].bch, MAX_DATA_MEM);
+		mISDN_initbchannel(&isar->ch[i].bch, MAX_DATA_MEM, 32);
 		isar->ch[i].bch.ch.nr = i + 1;
 		isar->ch[i].bch.ch.send = &isar_l2l1;
 		isar->ch[i].bch.ch.ctrl = isar_bctrl;
diff --git a/drivers/isdn/hardware/mISDN/netjet.c b/drivers/isdn/hardware/mISDN/netjet.c
index 3f28057..47d3074 100644
--- a/drivers/isdn/hardware/mISDN/netjet.c
+++ b/drivers/isdn/hardware/mISDN/netjet.c
@@ -408,7 +408,7 @@ read_dma(struct tiger_ch *bc, u32 idx, int cnt)
 	}
 
 	if (test_bit(FLG_TRANSPARENT, &bc->bch.Flags)) {
-		recv_Bchannel(&bc->bch, 0);
+		recv_Bchannel(&bc->bch, 0, false);
 		return;
 	}
 
@@ -426,7 +426,7 @@ read_dma(struct tiger_ch *bc, u32 idx, int cnt)
 						     DUMP_PREFIX_OFFSET, p,
 						     stat);
 			}
-			recv_Bchannel(&bc->bch, 0);
+			recv_Bchannel(&bc->bch, 0, false);
 			stat = bchannel_get_rxbuf(&bc->bch, bc->bch.maxlen);
 			if (stat < 0) {
 				pr_warning("%s.B%d: No memory for %d bytes\n",
@@ -758,21 +758,7 @@ nj_l2l1B(struct mISDNchannel *ch, struct sk_buff *skb)
 static int
 channel_bctrl(struct tiger_ch *bc, struct mISDN_ctrl_req *cq)
 {
-	int ret = 0;
-	struct tiger_hw *card  = bc->bch.hw;
-
-	switch (cq->op) {
-	case MISDN_CTRL_GETOP:
-		cq->op = 0;
-		break;
-		/* Nothing implemented yet */
-	case MISDN_CTRL_FILL_EMPTY:
-	default:
-		pr_info("%s: %s unknown Op %x\n", card->name, __func__, cq->op);
-		ret = -EINVAL;
-		break;
-	}
-	return ret;
+	return mISDN_ctrl_bchannel(&bc->bch, cq);
 }
 
 static int
@@ -1006,7 +992,8 @@ setup_instance(struct tiger_hw *card)
 	for (i = 0; i < 2; i++) {
 		card->bc[i].bch.nr = i + 1;
 		set_channelmap(i + 1, card->isac.dch.dev.channelmap);
-		mISDN_initbchannel(&card->bc[i].bch, MAX_DATA_MEM);
+		mISDN_initbchannel(&card->bc[i].bch, MAX_DATA_MEM,
+				   NJ_DMA_RXSIZE >> 1);
 		card->bc[i].bch.hw = card;
 		card->bc[i].bch.ch.send = nj_l2l1B;
 		card->bc[i].bch.ch.ctrl = nj_bctrl;
diff --git a/drivers/isdn/hardware/mISDN/w6692.c b/drivers/isdn/hardware/mISDN/w6692.c
index 8324b20..03fb4a3 100644
--- a/drivers/isdn/hardware/mISDN/w6692.c
+++ b/drivers/isdn/hardware/mISDN/w6692.c
@@ -688,7 +688,7 @@ W6692B_interrupt(struct w6692_hw *card, int ch)
 			if (count == 0)
 				count = W_B_FIFO_THRESH;
 			W6692_empty_Bfifo(wch, count);
-			recv_Bchannel(&wch->bch, 0);
+			recv_Bchannel(&wch->bch, 0, false);
 		}
 	}
 	if (stat & W_B_EXI_RMR) {
@@ -704,9 +704,8 @@ W6692B_interrupt(struct w6692_hw *card, int ch)
 				    W_B_CMDR_RRST | W_B_CMDR_RACT);
 		} else {
 			W6692_empty_Bfifo(wch, W_B_FIFO_THRESH);
-			if (test_bit(FLG_TRANSPARENT, &wch->bch.Flags) &&
-			    wch->bch.rx_skb && (wch->bch.rx_skb->len > 0))
-				recv_Bchannel(&wch->bch, 0);
+			if (test_bit(FLG_TRANSPARENT, &wch->bch.Flags))
+				recv_Bchannel(&wch->bch, 0, false);
 		}
 	}
 	if (stat & W_B_EXI_RDOV) {
@@ -979,20 +978,7 @@ w6692_l2l1B(struct mISDNchannel *ch, struct sk_buff *skb)
 static int
 channel_bctrl(struct bchannel *bch, struct mISDN_ctrl_req *cq)
 {
-	int	ret = 0;
-
-	switch (cq->op) {
-	case MISDN_CTRL_GETOP:
-		cq->op = 0;
-		break;
-		/* Nothing implemented yet */
-	case MISDN_CTRL_FILL_EMPTY:
-	default:
-		pr_info("%s: unknown Op %x\n", __func__, cq->op);
-		ret = -EINVAL;
-		break;
-	}
-	return ret;
+	return mISDN_ctrl_bchannel(bch, cq);
 }
 
 static int
@@ -1303,7 +1289,8 @@ setup_instance(struct w6692_hw *card)
 	card->dch.hw = card;
 	card->dch.dev.nrbchan = 2;
 	for (i = 0; i < 2; i++) {
-		mISDN_initbchannel(&card->bc[i].bch, MAX_DATA_MEM);
+		mISDN_initbchannel(&card->bc[i].bch, MAX_DATA_MEM,
+				   W_B_FIFO_THRESH);
 		card->bc[i].bch.hw = card;
 		card->bc[i].bch.nr = i + 1;
 		card->bc[i].bch.ch.nr = i + 1;
diff --git a/drivers/isdn/mISDN/hwchannel.c b/drivers/isdn/mISDN/hwchannel.c
index 3c2145d..d42ad0e 100644
--- a/drivers/isdn/mISDN/hwchannel.c
+++ b/drivers/isdn/mISDN/hwchannel.c
@@ -81,10 +81,16 @@ mISDN_initdchannel(struct dchannel *ch, int maxlen, void *phf)
 EXPORT_SYMBOL(mISDN_initdchannel);
 
 int
-mISDN_initbchannel(struct bchannel *ch, int maxlen)
+mISDN_initbchannel(struct bchannel *ch, unsigned short maxlen,
+		   unsigned short minlen)
 {
 	ch->Flags = 0;
+	ch->minlen = minlen;
+	ch->next_minlen = minlen;
+	ch->init_minlen = minlen;
 	ch->maxlen = maxlen;
+	ch->next_maxlen = maxlen;
+	ch->init_maxlen = maxlen;
 	ch->hw = NULL;
 	ch->rx_skb = NULL;
 	ch->tx_skb = NULL;
@@ -134,6 +140,10 @@ 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);
+	ch->minlen = ch->init_minlen;
+	ch->next_minlen = ch->init_minlen;
+	ch->maxlen = ch->init_maxlen;
+	ch->next_maxlen = ch->init_maxlen;
 }
 EXPORT_SYMBOL(mISDN_clear_bchannel);
 
@@ -148,6 +158,33 @@ mISDN_freebchannel(struct bchannel *ch)
 }
 EXPORT_SYMBOL(mISDN_freebchannel);
 
+int
+mISDN_ctrl_bchannel(struct bchannel *bch, struct mISDN_ctrl_req *cq)
+{
+	int ret = 0;
+
+	switch (cq->op) {
+	case MISDN_CTRL_GETOP:
+		cq->op = MISDN_CTRL_RX_BUFFER;
+		break;
+	case MISDN_CTRL_RX_BUFFER:
+		if (cq->p2 > MISDN_CTRL_RX_SIZE_IGNORE)
+			bch->next_maxlen = cq->p2;
+		if (cq->p1 > MISDN_CTRL_RX_SIZE_IGNORE)
+			bch->next_minlen = cq->p1;
+		/* we return the old values */
+		cq->p1 = bch->minlen;
+		cq->p2 = bch->maxlen;
+		break;
+	default:
+		pr_info("mISDN unhandled control %x operation\n", cq->op);
+		ret = -EINVAL;
+		break;
+	}
+	return ret;
+}
+EXPORT_SYMBOL(mISDN_ctrl_bchannel);
+
 static inline u_int
 get_sapi_tei(u_char *p)
 {
@@ -197,7 +234,7 @@ recv_Echannel(struct dchannel *ech, struct dchannel *dch)
 EXPORT_SYMBOL(recv_Echannel);
 
 void
-recv_Bchannel(struct bchannel *bch, unsigned int id)
+recv_Bchannel(struct bchannel *bch, unsigned int id, bool force)
 {
 	struct mISDNhead *hh;
 
@@ -211,6 +248,9 @@ recv_Bchannel(struct bchannel *bch, unsigned int id)
 		dev_kfree_skb(bch->rx_skb);
 		bch->rx_skb = NULL;
 	} else {
+		if (test_bit(FLG_TRANSPARENT, &bch->Flags) &&
+		    (bch->rx_skb->len < bch->minlen) && !force)
+				return;
 		hh = mISDN_HEAD_P(bch->rx_skb);
 		hh->prim = PH_DATA_IND;
 		hh->id = id;
@@ -426,7 +466,7 @@ bchannel_get_rxbuf(struct bchannel *bch, int reqlen)
 				   bch->nr, reqlen, len);
 			if (test_bit(FLG_TRANSPARENT, &bch->Flags)) {
 				/* send what we have now and try a new buffer */
-				recv_Bchannel(bch, 0);
+				recv_Bchannel(bch, 0, true);
 			} else {
 				/* on HDLC we have to drop too big frames */
 				return -EMSGSIZE;
@@ -435,12 +475,25 @@ bchannel_get_rxbuf(struct bchannel *bch, int reqlen)
 			return len;
 		}
 	}
+	/* update current min/max length first */
+	if (unlikely(bch->maxlen != bch->next_maxlen))
+		bch->maxlen = bch->next_maxlen;
+	if (unlikely(bch->minlen != bch->next_minlen))
+		bch->minlen = bch->next_minlen;
 	if (unlikely(reqlen > bch->maxlen))
 		return -EMSGSIZE;
-	if (test_bit(FLG_TRANSPARENT, &bch->Flags))
-		len = reqlen;
-	else /* with HDLC we do not know the length yet */
+	if (test_bit(FLG_TRANSPARENT, &bch->Flags)) {
+		if (reqlen >= bch->minlen) {
+			len = reqlen;
+		} else {
+			len = 2 * bch->minlen;
+			if (len > bch->maxlen)
+				len = bch->maxlen;
+		}
+	} else {
+		/* with HDLC we do not know the length yet */
 		len = bch->maxlen;
+	}
 	bch->rx_skb = mI_alloc_skb(len, GFP_ATOMIC);
 	if (!bch->rx_skb) {
 		pr_warning("B%d receive no memory for %d bytes\n",
diff --git a/drivers/isdn/mISDN/l1oip_core.c b/drivers/isdn/mISDN/l1oip_core.c
index 0f88acf..db50f78 100644
--- a/drivers/isdn/mISDN/l1oip_core.c
+++ b/drivers/isdn/mISDN/l1oip_core.c
@@ -1420,7 +1420,7 @@ init_card(struct l1oip *hc, int pri, int bundle)
 		bch->nr = i + ch;
 		bch->slot = i + ch;
 		bch->debug = debug;
-		mISDN_initbchannel(bch, MAX_DATA_MEM);
+		mISDN_initbchannel(bch, MAX_DATA_MEM, 0);
 		bch->hw = hc;
 		bch->ch.send = handle_bmsg;
 		bch->ch.ctrl = l1oip_bctrl;
diff --git a/include/linux/mISDNhw.h b/include/linux/mISDNhw.h
index a86d86b..226886c 100644
--- a/include/linux/mISDNhw.h
+++ b/include/linux/mISDNhw.h
@@ -154,7 +154,12 @@ struct bchannel {
 	struct timer_list	timer;
 	/* receive data */
 	struct sk_buff		*rx_skb;
-	int			maxlen;
+	unsigned short		maxlen;
+	unsigned short		init_maxlen; /* initial value */
+	unsigned short		next_maxlen; /* pending value */
+	unsigned short		minlen; /* for transparent data */
+	unsigned short		init_minlen; /* initial value */
+	unsigned short		next_minlen; /* pending value */
 	/* send data */
 	struct sk_buff		*next_skb;
 	struct sk_buff		*tx_skb;
@@ -169,10 +174,12 @@ struct bchannel {
 };
 
 extern int	mISDN_initdchannel(struct dchannel *, int, void *);
-extern int	mISDN_initbchannel(struct bchannel *, int);
+extern int	mISDN_initbchannel(struct bchannel *, unsigned short,
+				   unsigned short);
 extern int	mISDN_freedchannel(struct dchannel *);
 extern void	mISDN_clear_bchannel(struct bchannel *);
 extern int	mISDN_freebchannel(struct bchannel *);
+extern int	mISDN_ctrl_bchannel(struct bchannel *, struct mISDN_ctrl_req *);
 extern void	queue_ch_frame(struct mISDNchannel *, u_int,
 			int, struct sk_buff *);
 extern int	dchannel_senddata(struct dchannel *, struct sk_buff *);
@@ -180,7 +187,7 @@ extern int	bchannel_senddata(struct bchannel *, struct sk_buff *);
 extern int      bchannel_get_rxbuf(struct bchannel *, int);
 extern void	recv_Dchannel(struct dchannel *);
 extern void	recv_Echannel(struct dchannel *, struct dchannel *);
-extern void	recv_Bchannel(struct bchannel *, unsigned int id);
+extern void	recv_Bchannel(struct bchannel *, unsigned int, bool);
 extern void	recv_Dchannel_skb(struct dchannel *, struct sk_buff *);
 extern void	recv_Bchannel_skb(struct bchannel *, struct sk_buff *);
 extern int	get_next_bframe(struct bchannel *);
diff --git a/include/linux/mISDNif.h b/include/linux/mISDNif.h
index ce6e613..246a352 100644
--- a/include/linux/mISDNif.h
+++ b/include/linux/mISDNif.h
@@ -37,7 +37,7 @@
  */
 #define	MISDN_MAJOR_VERSION	1
 #define	MISDN_MINOR_VERSION	1
-#define MISDN_RELEASE		28
+#define MISDN_RELEASE		29
 
 /* primitives for information exchange
  * generell format
@@ -365,6 +365,7 @@ clear_channelmap(u_int nr, u_char *map)
 #define MISDN_CTRL_LOOP			0x0001
 #define MISDN_CTRL_CONNECT		0x0002
 #define MISDN_CTRL_DISCONNECT		0x0004
+#define MISDN_CTRL_RX_BUFFER		0x0008
 #define MISDN_CTRL_PCMCONNECT		0x0010
 #define MISDN_CTRL_PCMDISCONNECT	0x0020
 #define MISDN_CTRL_SETPEER		0x0040
@@ -387,6 +388,12 @@ clear_channelmap(u_int nr, u_char *map)
 #define MISDN_CTRL_HFC_WD_INIT		0x4009
 #define MISDN_CTRL_HFC_WD_RESET		0x400A
 
+/* special RX buffer value for MISDN_CTRL_RX_BUFFER request.p1 is the minimum
+ * buffer size request.p2 the maximum. Using  MISDN_CTRL_RX_SIZE_IGNORE will
+ * not change the value, but still read back the actual stetting.
+ */
+#define MISDN_CTRL_RX_SIZE_IGNORE	-1
+
 /* socket options */
 #define MISDN_TIME_STAMP		0x0001