Bus bridge arbitration method
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorKenichi Kawaguchi
Life of this patent
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Abstract
A bus bridge is connected to a first bus and a second bus. In the bus bridge, an arbiter grants ownership of the first bus to one of a plurality of devices connected to the first bus. A detecting unit detects a read cycle initiated by the device on the first bus to read data from a memory which is also accessible by another device connected to the second bus. A first signaling unit sends a first signal to the arbiter, when the data is not yet transferable to the device when the read cycle is detected. A second signaling unit sends a second signal to the arbiter, when the data becomes transferable to the device. The arbiter deprives the device of the ownership of the first bus upon receipt of the first signal, and withholds from granting the ownership to the device until receipt of the second signal.
Claims12
A bus bridge that is connected to a first bus and a second bus, comprising:
- an arbiter operable to grant ownership of the first bus to one of a plurality of devices connected to the first bus;
- a detecting unit operable to detect a read cycle initiated by the device on the first bus, the read cycle being a cycle to read data stored in a memory which can also be accessed by another device connected to the second bus;
- a first signaling unit operable to send a first signal to the arbiter, when the data is not yet transferable to the device at a time when the read cycle is detected;
- and
- a second signaling unit operable to send a second signal to the arbiter, when the data becomes transferable to the device,
- wherein the arbiter deprives the device of the ownership of the first bus upon receipt of the first signal, and withholds from granting the ownership of the first bus to the device until receipt of the second signal.
A computer system, comprising:
- a first bus to which a plurality of devices are connected;
- a second bus to which a memory is connected;
- an arbiter operable to grant ownership of the first bus to one of the plurality of devices;
- and
- a bus bridge which is connected to the first bus and the second bus,
- wherein the bus bridge includes:
- a detecting unit operable to detect a read cycle initiated by the device on the first bus, the read cycle being a cycle to read data stored in the memory;
- a first signaling unit operable to send a first signal to the arbiter, when the data is not yet transferable to the device at a time when the read cycle is detected;
- and
- a second signaling unit operable to send a second signal to the arbiter, when the data becomes transferable to the device,
- wherein the arbiter deprives the device of the ownership of the first bus upon receipt of the first signal, and withholds from granting the ownership of the first bus to the device until receipt of the second signal.
An arbitration method for use in an arbiter that grants ownership of a bus to one of a plurality of devices connected to the bus, comprising:
- a step of depriving the device of the ownership of the bus, when the device, having been granted the ownership of the bus, initiates a read cycle on the bus to read data but the data is not yet transferable to the device;
- and
- a step of withholding from granting the ownership of the bus to the device until the data becomes transferable to the device.
Dependencies are inferred from the claim text.