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>

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;