Arm Limited

Lars Ericsson

Daren Croxford

Tom Cooksey

Jon Erik Oterhals

Jørn Nystad

Eivind Liland

Sean Tristram Ellis

Daren Croxdord

A display controller provides an output frame to a display for display by sending respective output surface regions that together form the output frame, each respective region of the output surface being generated from a respective region or regions of one or more input surfaces, to the display. When a new version of an output surface region is generated, the display controller determines whether the output surface region has been unchanged for a period, and if it has, then stores the generated output surface region in a frame buffer. Then, for the subsequent frame, checks are performed to see if the output surface region could have changed. If there is no change the stored version of the output surface region is reused, but if there is a change in the output surface region, the output surface region is regenerated.

Method of and apparatus for displaying an output surface in data processing systems

In a compositing window system, as a respective version of the window for an application is written into a window buffer, a corresponding set of per tile signatures indicative of the content of each respective tile in the window buffer is generated and stored. When an updated version of the window is stored into a window buffer, the set of signature values for the updated version is compared to the set of signature values for the previous version in the window buffer to determine which tiles' content has changed. The set of tiles found to have changed is used to generate a set of regions for a window compositor to write to a window in a display frame buffer to update the window in the display frame buffer to display the new version of the window.

Methods of and apparatus for displaying windows on a display

A transaction elimination hardware unit controls the writing to a frame buffer in a memory of tiles generated by a tile-based graphics processor. The transaction elimination hardware unit has a signature generator that generates a signature representative of the content of the tile for each tile. A signature comparator then compares the signature of a new tile received from the graphics processor with the signatures of one or more tiles already stored in the frame buffer to see if the signatures match. If the signatures do not match, then the signature comparator controls a write controller to write the new tile to the frame buffer. On the other hand, if the signatures match, then no data is written to the frame buffer and the existing tile is allowed to remain in the frame buffer. In this way, a tile is only written to the frame buffer if it is found by the signature comparison to differ from the tile or tiles that are already stored in the frame buffer that it is compared with.

Graphics processing system

A graphics processorincludes after its tile rendering logic, a transaction elimination unitthat includes data block generation logicand block comparison logic. The block generation logicgenerates data blocks from the rendered tiles produced by the tile rendering logic. The data blocks are then stored in buffers. Comparison logicthen compares a new data block with the previous data block (which will already be stored in the buffers), and generates an output metadata bit indicating whether the blocks can be considered to be the same or not, on the basis of the comparison. The meta-data output bits are stored appropriately in a meta-data bitmapin main memorythat is associated with the output data array in question. If the blocks are determined to be different by the comparison logic then the new data block is written from the buffersto the frame bufferin the main memory. On the other hand, if the two blocks are considered to be similar to each other, the new block is not written into the data array in the frame buffer

Graphics processing systems

In a data processing system, an output surface, such as frame to be displayed, is generated as a plurality of respective regions with each respective region of the output surface being generated from a respective region or regions of one or more input surfaces. When a new version of the output surface is to be generated, for each region of the output surface it is determined which region or regions of the input surface or surfaces contribute to the region of the output surfaceand then checked whether the contributing region or regions of the input surface or surfaces have changed since the previous version of the output surface region was generated. If there has been a change in the contributing region or regions of the input surface or surfaces since the previous version of the region in the output surface was generated, the region of the output surface is regenerated

Method and apparatus for generating an output surface from one or more input surfaces in data processing systems

A display controller reads blocks of data from a frame buffer and stores them in a local memory buffer of the display controller before outputting the blocks of data to a display. The display controller uses similarity meta-data associated with the output frame in the frame buffer to determine whether a new block of data to be processed for display is similar to a block of data already stored in the local memory of the display controller or not. If it is determined that the data block to be processed is similar to a data block already stored in the local buffer of the display controller, the display controller does not read a new data block from the frame buffer but instead provides the existing data block in its buffer to the display.

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Cambridge, United Kingdom

Lars Ericsson