Pci bus master retry fixup

Abstract

A technique for providing PCI bus mastering compatibility for legacy PCI bus devices which may not support PCI bus mastering RETRY protocols. DLDMM provider software in a device driver for a target device may provide a callback signal at a callback address to DLDMM client software in a device driver for a bus mastering PCI device. The callback address may be used by the DLDMM client software to signal the bus mastering PCI device to suspend operation in the event of an interrupting event. The bus mastering PCI device may then generate in driver software a RETRY signal to the device driver of the target device. If the interrupting event is over, a signal may be sent by the DLDMM provider software in response to the RETRY signal to the DLDMM client software indicating that the bus mastering device may resume operation. The bus mastering device may then resume operation where left off. The technique of the present invention has particular application to multimedia computer systems where a bus mastering device (e.g., MPEG decoder or the like) may wish to stream MotionVideo.TM. data to a target adapter (e.g., VGA controller or the like) using bus mastering techniques. Prior art PCI VGA adapters may not support PCI RETRY protocols and thus attempts to send data to such devices using bus mastering may fail.