Index: Linux/drivers/media/video/bttv-risc.c
===================================================================
--- Linux.orig/drivers/media/video/bttv-risc.c	2006-01-24 10:09:21.000000000 +0100
+++ Linux/drivers/media/video/bttv-risc.c	2006-01-24 10:16:06.000000000 +0100
@@ -51,8 +51,10 @@
 	int rc;
 
 	/* estimate risc mem: worst case is one write per page border +
-	   one write per scan line + sync + jump (all 2 dwords) */
-	instructions  = (bpl * lines) / PAGE_SIZE + lines;
+	   one write per scan line + sync + jump (all 2 dwords).  padding
+	   can cause next bpl to start close to a page border.  First DMA
+	   region may be smaller than PAGE_SIZE */
+	instructions  = 1 + ((bpl + padding) * lines) / PAGE_SIZE + lines;
 	instructions += 2;
 	if ((rc = btcx_riscmem_alloc(btv->c.pci,risc,instructions*8)) < 0)
 		return rc;
@@ -104,7 +106,7 @@
 
 	/* save pointer to jmp instruction address */
 	risc->jmp = rp;
-	BUG_ON((risc->jmp - risc->cpu + 2) / 4 > risc->size);
+	BUG_ON(4 * (risc->jmp - risc->cpu + 2) > risc->size);
 	return 0;
 }