diff --git a/Documentation/debugging-via-ohci1394.txt b/Documentation/debugging-via-ohci1394.txt
index 73473aa..fa0151a 100644
--- a/Documentation/debugging-via-ohci1394.txt
+++ b/Documentation/debugging-via-ohci1394.txt
@@ -22,10 +22,12 @@
 Retrieving a full system memory dump is also possible over the FireWire,
 using data transfer rates in the order of 10MB/s or more.
 
-Memory access is currently limited to the low 4G of physical address
-space which can be a problem on IA64 machines where memory is located
-mostly above that limit, but it is rarely a problem on more common
-hardware such as hardware based on x86, x86-64 and PowerPC.
+With most FireWire controllers, memory access is limited to the low 4 GB
+of physical address space.  This can be a problem on IA64 machines where
+memory is located mostly above that limit, but it is rarely a problem on
+more common hardware such as x86, x86-64 and PowerPC.  However, at least
+Agere/LSI FW643e and FW643e2 controllers are known to support access to
+physical addresses above 4 GB.
 
 Together with a early initialization of the OHCI-1394 controller for debugging,
 this facility proved most useful for examining long debugs logs in the printk
@@ -99,6 +101,9 @@
    compliant, they are based on TI PCILynx chips and require drivers for Win-
    dows operating systems.
 
+   The mentioned kernel log message contains ">4 GB phys DMA" in case of
+   OHCI-1394 controllers which support accesses above this limit.
+
 2) Establish a working FireWire cable connection:
 
    Any FireWire cable, as long at it provides electrically and mechanically
diff --git a/drivers/firewire/core-transaction.c b/drivers/firewire/core-transaction.c
index 0e79951..eb6935c 100644
--- a/drivers/firewire/core-transaction.c
+++ b/drivers/firewire/core-transaction.c
@@ -523,11 +523,11 @@
 static LIST_HEAD(address_handler_list);
 
 const struct fw_address_region fw_high_memory_region =
-	{ .start = 0x000100000000ULL, .end = 0xffffe0000000ULL,  };
+	{ .start = FW_MAX_PHYSICAL_RANGE, .end = 0xffffe0000000ULL, };
 EXPORT_SYMBOL(fw_high_memory_region);
 
 static const struct fw_address_region low_memory_region =
-	{ .start = 0x000000000000ULL, .end = 0x000100000000ULL,  };
+	{ .start = 0x000000000000ULL, .end = FW_MAX_PHYSICAL_RANGE, };
 
 #if 0
 const struct fw_address_region fw_private_region =
@@ -1217,7 +1217,7 @@
 }
 
 static struct fw_address_handler low_memory = {
-	.length			= 0x000100000000ULL,
+	.length			= FW_MAX_PHYSICAL_RANGE,
 	.address_callback	= handle_low_memory,
 };
 
diff --git a/drivers/firewire/core.h b/drivers/firewire/core.h
index 515a42c..c98764a 100644
--- a/drivers/firewire/core.h
+++ b/drivers/firewire/core.h
@@ -237,6 +237,9 @@
 
 #define LOCAL_BUS 0xffc0
 
+/* arbitrarily chosen maximum range for physical DMA: 128 TB */
+#define FW_MAX_PHYSICAL_RANGE		(128ULL << 40)
+
 void fw_core_handle_request(struct fw_card *card, struct fw_packet *request);
 void fw_core_handle_response(struct fw_card *card, struct fw_packet *packet);
 int fw_get_response_length(struct fw_request *request);
diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c
index 036fb3b..6f74d8d 100644
--- a/drivers/firewire/ohci.c
+++ b/drivers/firewire/ohci.c
@@ -2367,7 +2367,7 @@
 	reg_write(ohci, OHCI1394_FairnessControl, 0);
 	card->priority_budget_implemented = ohci->pri_req_max != 0;
 
-	reg_write(ohci, OHCI1394_PhyUpperBound, 0x00010000);
+	reg_write(ohci, OHCI1394_PhyUpperBound, FW_MAX_PHYSICAL_RANGE >> 16);
 	reg_write(ohci, OHCI1394_IntEventClear, ~0);
 	reg_write(ohci, OHCI1394_IntMaskClear, ~0);
 
@@ -3723,9 +3723,11 @@
 	version = reg_read(ohci, OHCI1394_Version) & 0x00ff00ff;
 	ohci_notice(ohci,
 		    "added OHCI v%x.%x device as card %d, "
-		    "%d IR + %d IT contexts, quirks 0x%x\n",
+		    "%d IR + %d IT contexts, quirks 0x%x%s\n",
 		    version >> 16, version & 0xff, ohci->card.index,
-		    ohci->n_ir, ohci->n_it, ohci->quirks);
+		    ohci->n_ir, ohci->n_it, ohci->quirks,
+		    reg_read(ohci, OHCI1394_PhyUpperBound) ?
+			", >4 GB phys DMA" : "");
 
 	return 0;