diff --git a/src/add-ons/kernel/busses/usb/ohci.h b/src/add-ons/kernel/busses/usb/ohci.h
index 9c48da1a7c..59ce46c090 100644
--- a/src/add-ons/kernel/busses/usb/ohci.h
+++ b/src/add-ons/kernel/busses/usb/ohci.h
@@ -48,6 +48,17 @@ typedef struct hcd_soft_itransfer
 
 #define	OHCI_NUMBER_OF_ENDPOINTS	(2 * OHCI_NUMBER_OF_INTERRUPTS - 1)
 
+// Note: the controller returns only the physical
+// address of the first processed descriptor of
+// an heterogeneous list (isochronous + generic). Unfortunately
+// we don't have a way to know whether the descriptor is
+// generic or isochronous, either way to translate the address back to
+// kernel address. The physical address is used as the hash value.
+// (Kindly borrowed from *BSD)
+
+#define OHCI_HASH_SIZE 128
+#define HASH(x) (((x) >> 4) % OHCI_HASH_SIZE)
+
 
 class OHCI : public BusManager
 {
@@ -128,9 +139,21 @@ static	int32						_FinishThread(void *data);
 										iovec *vector,
 										size_t vectorCount);
 
-		// OHCI needs this function
-		addr_t						_LogicalAddress(addr_t physical);
-		bool						_IsIsochronous(addr_t logical);
+		// Hash tables related methods
+		void						_AddDescriptorToHash(
+										ohci_general_td *descriptor);
+		void						_RemoveDescriptorFromHash(
+										addr_t physicalAddress);
+		ohci_general_td				*_FindDescriptorInHash(
+										addr_t physicalAddress);
+
+		void						_AddIsoDescriptorToHash(
+										ohci_isochronous_td *descriptor);
+		void						_RemoveIsoDescriptorFromHash(
+										addr_t physicalAddress);
+		ohci_isochronous_td			*_FindIsoDescriptorInHash(
+										addr_t physicalAddress);
+
 
 		// Register functions
 inline	void						_WriteReg(uint32 reg, uint32 value);
diff --git a/src/add-ons/kernel/busses/usb/ohci_hardware.h b/src/add-ons/kernel/busses/usb/ohci_hardware.h
index c097f76d5d..ffd7c91e0b 100644
--- a/src/add-ons/kernel/busses/usb/ohci_hardware.h
+++ b/src/add-ons/kernel/busses/usb/ohci_hardware.h
@@ -335,16 +335,19 @@ typedef struct ohci_endpoint_descriptor
 
 typedef struct ohci_general_td
 {
-	// Hardware part
+	// Hardware part 16 bytes
 	uint32	flags;						// Flags field
 	uint32	buffer_physical;			// Physical buffer pointer
 	uint32 	next_physical_descriptor;	// Physical pointer next descriptor
 	uint32 	last_physical_byte_address;	// Physical pointer to buffer end
 	// Software part
-	addr_t	physical_address;			// Physical pointer to this address
+	addr_t	physical_address;			// Physical address of this descriptor
 	void	*buffer_logical;			// Logical pointer to the buffer
 	void	*next_logical_descriptor;	// Logical pointer next descriptor
 	size_t	buffer_size;				// Size of the buffer
+	void	*endpoint;					// Necessary when there is an error
+	void	*transfer;					// Pointer to the transfer
+	bool	is_last;					// Last descriptor of the transfer
 };
 
 #define	OHCI_BUFFER_ROUNDING			0x00040000
@@ -373,11 +376,14 @@ typedef struct ohci_general_td
 #define OHCI_ITD_NOFFSET 8
 typedef struct ohci_isochronous_td
 {
+	// Hardware part 32 byte
 	uint32		flags;
 	uint32		buffer_page_byte_0;			// Physical page number of byte 0
 	uint32		next_physical_descriptor;	// Next isochronous transfer descriptor
 	uint32		last_byte_address;			// Physical buffer end
 	uint16		offset[OHCI_ITD_NOFFSET];	// Buffer offsets
+	// Software part
+	addr_t		physical_address;			// Physical address of this descriptor
 };
 
 #define	OHCI_ITD_GET_STARTING_FRAME(x)			((x) & 0x0000ffff)