1 files changed, 39 insertions, 2 deletions

diff --git a/drivers/isdn/hardware/mISDN/hfcpci.c b/drivers/isdn/hardware/mISDN/hfcpci.c
index cd8302af40eb..80c356e5dbe1 100644
--- a/drivers/isdn/hardware/mISDN/hfcpci.c
+++ b/drivers/isdn/hardware/mISDN/hfcpci.c
@@ -751,6 +751,36 @@ hfcpci_fill_fifo(struct bchannel *bch)
                             /* 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;
+                        new_z1 = le16_to_cpu(*z1t) + count;
+                           /* new buffer Position */
+                        if (new_z1 >= (B_FIFO_SIZE + B_SUB_VAL))
+                                new_z1 -= B_FIFO_SIZE;  /* buffer wrap */
+                        dst = bdata + (le16_to_cpu(*z1t) - B_SUB_VAL);
+                        maxlen = (B_FIFO_SIZE + B_SUB_VAL) - le16_to_cpu(*z1t);
+                            /* end of fifo */
+                        if (bch->debug & DEBUG_HW_BFIFO)
+                                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 */
+                        count -= maxlen;                /* remaining bytes */
+                        if (count) {
+                                dst = bdata;            /* start of buffer */
+                                memset(dst, 0x2a, count);
+                        }
+                        *z1t = cpu_to_le16(new_z1);     /* now send data */
+                }
+
 next_t_frame:
                 count = bch->tx_skb->len - bch->tx_idx;
                 /* maximum fill shall be HFCPCI_BTRANS_MAX */
@@ -1481,11 +1511,17 @@ deactivate_bchannel(struct bchannel *bch)
 static int
 channel_bctrl(struct bchannel *bch, struct mISDN_ctrl_req *cq)
 {
-        int                     ret = 0;
+        int     ret = 0;
 
         switch (cq->op) {
         case MISDN_CTRL_GETOP:
-                cq->op = 0;
+                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:
                 printk(KERN_WARNING "%s: unknown Op %x\n", __func__, cq->op);
@@ -1903,6 +1939,7 @@ 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))