Electrical computers and digital data processing systems: input/ – Intrasystem connection – Bus access regulation
Reexamination Certificate
2000-10-18
2003-12-02
Lefkowitz, Sumati (Department: 2189)
Electrical computers and digital data processing systems: input/
Intrasystem connection
Bus access regulation
C710S017000, C714S056000
Reexamination Certificate
active
06658510
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to peripheral devices in a computer system, and more particularly to accessing peripheral devices in a computer system.
BACKGROUND OF THE INVENTION
The accessing of peripherals by a microprocessor is well known in the art. Typically, an input/output (I/O) request, i.e., request for writing/reading of data, is sent from the microprocessor to the peripheral via a peripheral bus. In many peripheral bus designs, when a peripheral is addressed by the microprocessor, that peripheral is expected to return an indication onto the peripheral bus that it is ready to accept or supply data. There is a certain period of time during which a hung bus detector will wait for this indication from the peripheral. This is commonly referred to as the “bus timeout period”. If the bus timeout period is exceeded before the indication is received from the peripheral, typically the peripheral is assumed to be too busy or has encountered an error. This is commonly referred to as a “hung” condition. Conventionally, some part of the hardware of the microprocessor's device is then reset to free the hung condition. Each time the hardware is reset, a certain amount of device down time is wasted.
Also, with complex computer systems, such as with network communications devices, peripherals connected to the microprocessor via the peripheral bus are often complex “application specific integrated circuits”, or ASICs, that themselves interface with multiple devices and run complex state machines at the same time. This complexity can increase the variability in response time to I/O requests from the microprocessor, especially if the ASIC must also process highly variable network traffic.
Accordingly, there exists a need for an improved method and system for managing peripheral bus timeouts. The improved method and system should avoid unnecessary resetting of the device hardware. The present invention addresses such a need.
SUMMARY OF THE INVENTION
The present invention provides an improved method and system for managing peripheral bus timeouts. The method includes: sending a request to a peripheral in a performance of a task; determining that a peripheral bus timeout occurred; sending an interrupt signal; retrying for an access to the peripheral; completing the request if the retry for the access to the peripheral is successful; and resuming the performance of the task. The present invention provides a software method in which an input/output (I/O) request to a peripheral is sent by a recoverable access routine. When a bus timeout occurs, a hung bus detector asserts an interrupt signal. The peripheral bus is freed from the hung condition. The recoverable access routine is suspended, and a bus timeout interrupt handler is then loaded. The interruption and the freeing of the peripheral bus frees the microprocessor from the processing of the I/O request so that other requests may be performed. During the suspension of the recoverable access routine, a retry routine retries the I/O request. If the retry routine is successful in completing the I/O request, the result of the request is provided to the recoverable access routine, and the recoverable access routine is resumed to complete the task. In this manner, a peripheral bus timeout is managed without the need to reset the device hardware.
REFERENCES:
patent: 3997896 (1976-12-01), Cassarino et al.
patent: 4245299 (1981-01-01), Woods et al.
patent: 4872110 (1989-10-01), Smith et al.
patent: 4947316 (1990-08-01), Fisk et al.
patent: 5193181 (1993-03-01), Barlow et al.
patent: 5287362 (1994-02-01), Liencres
patent: 5495585 (1996-02-01), Datwyler et al.
patent: 5572734 (1996-11-01), Narad et al.
patent: 5644733 (1997-07-01), Kalish et al.
patent: 5682551 (1997-10-01), Pawlowski et al.
patent: 5706446 (1998-01-01), Kalish et al.
patent: 5761445 (1998-06-01), Nguyen
patent: 5764935 (1998-06-01), Bechtolsheim et al.
patent: 5768620 (1998-06-01), Johnson et al.
patent: 5923858 (1999-07-01), Kanekal
patent: 5941967 (1999-08-01), Zulian
patent: 6000040 (1999-12-01), Culley et al.
patent: 6496890 (2002-12-01), Azevedo et al.
patent: 02208715 (1990-08-01), None
patent: 7175729 (1995-07-01), None
Lefkowitz Sumati
Munoz-Bustamante Carlos
Sawyer Law Group LLP
LandOfFree
Software method to retry access to peripherals that can... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Software method to retry access to peripherals that can..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Software method to retry access to peripherals that can... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3176316