Controller and transfer speed control method

Abstract

A USB 3 host controller according to the present invention includes a transfer speed switching unit besides a transfer data converting unit that mutually converts transfer data from a USB device and transfer data from a PCI Express bus. The transfer speed switching unit receives transfer information regarding data transfer from the USB device via a USB 3 interface when the USB device is connected, and identifies a transfer speed used by a PC side according to the transfer information or a result of analyzing the transfer information. Then, when a current transfer speed of the PC side is different from the identified transfer speed, the transfer speed switching unit transmits a speed switching signal indicating switch to the identified transfer speed to a PCI master via a PCI express interface.

What is claimed is: 
     
         1 . A controller connected between a first device that adopts a bus standard A specifying a plurality of transfer speeds for data transfer and a second device that adopts a bus standard B, the controller comprising:
 a first interface that is connected to the first device and transmits and is configured to receive data to and from the first device;   a second interface that is connected to the second device and is configured to transmit and receive data to and from the second device;   a transfer data converting unit that is configured to convert data of the bus standard A and data of the bus standard B between the first interface and the second interface; and   a transfer speed switching unit that is configured to receive transfer information regarding data transfer from the first device via the first interface when the first device is connected, to evaluate a target transfer speed to be used by the second device according to the transfer information or a result of analyzing the transfer information, and when a current transfer speed input from the second device is different from the target transfer speed, to transmit a speed switching signal to the second device via the second interface, the speed switching signal indicating switch to the target transfer speed,   wherein   the bus standard A specifies a transfer speed A 1  as a speed for transferring data and a transfer speed A 2  that is faster than the transfer speed A 1 ,   the bus standard B specifies a transfer speed B 1  as the speed for transferring data and a transfer speed B 2  that is faster than the transfer speed B 1  and corresponds to the transfer speed A 2 ,   and wherein the current transfer speed is B 1  and the target transfer speed is B 2 .   
     
     
         2 . The controller according to  claim 1 , wherein
 the transfer information includes a transfer type indicating a different data transfer system according to a kind of transfer data and a transfer method,   the transfer type specifies a first transfer type for transferring control data, a second transfer type for transferring data when the data transfer is necessary, a third transfer type for transferring a large amount of data, and a fourth transfer type for transferring data real-time,   the second device is previously set to the transfer speed B 1 , and   when the currently connected first device is capable of transferring data at the transfer speed A 2  and transfers the data with the third transfer type, the transfer speed switching unit transmits the speed switching signal that indicates the switch to the transfer speed B 2  to the second device via the second interface.   
     
     
         3 . The controller according to  claim 2 , wherein
 when the currently connected first device is capable of transferring data at the transfer speed A 2  and transfers the data with the fourth transfer type, the transfer speed switching unit transmits the speed switching signal that indicates the switch to the transfer speed B 2  to the second device via the second interface.   
     
     
         4 . The controller according to  claim 1 , wherein the bus standard A is a USB standard and the bus standard B is a PCI Express standard. 
     
     
         5 . The controller according to  claim 4 , wherein the transfer speed A of the bus standard A is LowSpeed (1.2 Mbps), FullSpeed (12 Mbps), or HighSpeed (480 Mbps), and the transfer speed A 2  is SuperSpeed (5 Gbps). 
     
     
         6 . The controller according to  claim 4 , wherein the transfer speed B 1  of the bus standard B is Generation1 (2.5 GTps) and the transfer speed B is Generation2 (5 GTps). 
     
     
         7 . The controller according to  claim 4 , wherein the first to the fourth transfer type are respectively Control transfer, Interrupt transfer, Bulk transfer, and Isochronous transfer.