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US006738068B2
(12) United States Patent ao) Patent No.: us 6,738,068 B2
Cohen et al. (45) Date of Patent: May 18,2004
(54) ENTERING AND EXITING POWER
MANAGED STATES WITHOUT DISRUPTING
ACCELERATED GRAPHICS PORT
TRANSACTIONS
(75) Inventors: Debra T. Cohen, Santa Clara, CA
(US); Leslie E. Cline, Sunnyvale, CA
(US); Barnes Cooper, Beaverton, OR
(US); Satchit Jain, San Jose, CA (US);
Anil V. Nanduri, Sunnyvale, CA (US)
(73) Assignee: Intel Corporation, Santa Clara, CA
(US)
( * ) Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) by 547 days.
(21) Appl. No.: 09/751,441
(22) Filed: Dec. 29, 2000
(65) Prior Publication Data
US 2002/0085008 Al Jul. 4, 2002
(51) Int. CI.7 G06F 13/14; G06F 1/26;
G06F 1/32; G06F 1/30; G06F 1/28; G06F 11/30
(52) U.S. CI 345/519; 713/320; 713/323;
713/324; 713/330; 713/340; 710/305
(58) Field of Search 345/519, 794,
345/522, 558, 520, 532; 710/309, 304, 303, 18, 260, 8; 712/34, 32; 713/323, 324, 322, 162, 310, 320, 300; 365/222
(56) References Cited
U.S. PATENT DOCUMENTS
5,471,625 A * 11/1995 Mussemann et al 713/322
An interface between an accelerated graphics port graphics controller (AGP-GC) and a core controller to prevent entry into a low power state from interfering with transfers to or from the AGP-GC that have been requested but not completed. The core controller can communicate to the AGP-GC an intent to enter a low power state, while the AGP-GC can communicate to the core controller the busy status of the AGP-GC. When the AGP-GC receives notice of an intent to enter a low power state, it can stop issuing requests to the core controller. When the core controller detects that the AGP-GC is busy, the core controller can postpone entry into the low power state until the AGP-GC completes any requests that are in progress. In an alternate use of the interface, if the AGP-GC wishes to make a request during a low power state, it can signal the core controller of this need by indicating a busy status, which can trigger the core controller to initiate an exit from the low power state.
12 Claims, 4 Drawing Sheets
