Patent ID: 7831748
Filing Date: 2010-11-09
Classification: G06F

Abstract:
1. A USB bus in a computing system, comprising: a USB root hub having a plurality of downstream ports and an upstream port; a USB host connected to the upstream port to transfer data to and from devices attached to said downstream ports; a USB host controller that interfaces the USB host to the computing system, wherein the root hub is configured to receive data packets from the upstream port and broadcast the data packets to active downstream ports, wherein a downstream port is active when a powered device is coupled to the downstream port; wherein the host controller is configured, based on information in individual data packets, to broadcast the data packets to all active downstream ports in a first mode of operation; wherein the host controller is configured, based on information in the individual data packets, to disable a transmission of individual data packets broadcasted to a specific active downstream port by blocking the individual data packets broadcasted to said specific port of said USB root hub in a second mode of operation; and wherein the host controller is configured to periodically send pulses operable to keep an active device in an active state to the specific downstream port in the second mode of operation while blocking the individual data packets.