Abstract: Methods, circuits, and apparatus for reducing memory bandwidth used by a graphics processor. Uncompressed tiles are read from a display buffer portion of a graphics memory and received by an encoder. The uncompressed tiles are compressed and written back to the graphics memory. When a tile is needed again before it has been modified, the compressed version is read from memory, uncompressed, and displayed. To reduce the number of unnecessary writes of compressed tiles to memory, a tile is only written to memory if it has remained static for some number of refresh cycles. Also, to prevent a large number of compressed tiles being written to the display buffer in one refresh cycle, the encoder can be throttled after a number of tiles have been written. Validity information can be stored for use by a CRTC. If a tile is updated, the validity information is updated such that invalid compressed data is not read from memory and displayed.

Abstract: Methods, circuits, and apparatus for reducing memory bandwidth used by a graphics processor. Uncompressed tiles are read from a display buffer portion of a graphics memory and received by an encoder. The uncompressed tiles are compressed and written back to the graphics memory. When a tile is needed again before it has been modified, the compressed version is read from memory, uncompressed, and displayed. To reduce the number of unnecessary writes of compressed tiles to memory, a tile is only written to memory if it has remained static for some number of refresh cycles. Also, to prevent a large number of compressed tiles being written to the display buffer in one refresh cycle, the encoder can be throttled after a number of tiles have been written. Validity information can be stored for use by a CRTC. If a tile is updated, the validity information is updated such that invalid compressed data is not read from memory and displayed.