An Apple patent (number 20110267359) for systems and methods for hot plug GPU power control has appeared at the US Patent & Trademark Office. It shows that Apple is working on ways for Macs and iOS devices to more efficiently manage multiple graphics processors.

Per the patent, systems and methods include an electronic device having multiple GPUs and a GPU power control process that controls switching between a first GPU and a second GPU, such as a high performance GPU. The electronic device may be coupled to an external display by a passive adapter or an active adapter. The GPU power control process may determine if the second GPU is active and switch to the second GPU upon connection of the external display through either the passive adapter or the active adapter.

Upon connection of an active adapter, the GPU power control process may use hot plug functionality to determine connection of the external display to the active adapter and provide appropriate switching in response thereto. The inventors are David J. Redman and Wai Yu Trevor Tsang.

Here's Apple's background and summary of the invention: "Electronic devices, including computers and portable devices such as phones and media players, typically include display screens to display user interfaces, applications, video playback, video games, etc. A display of an electronic device may be driven by a specialized processor, referred to as a graphics processing unit (GPU). The GPU may drive an internal display of the electronic device. Additionally, or alternatively, a GPU of such devices may drive an external display connected to the electronic device.

"Some electronic devices may include multiple GPUs, such as a dual GPU device, in which one or the other GPU is used to drive a display. However, in such devices, a user may have to power cycle the device to switch GPU resources for applications from one GPU to the other GPU, and the switching may require manual operation from the user. This action may be disruptive for the user and may discourage use of the GPU resource switching capability. Further, the GPUs may have different capabilities, and a user may not switch to the appropriate GPU for the appropriate display.

"A system and method are provided that include a GPU power control process that facilitates switching between a first GPU and a second GPU based on connection of an external display through an adapter. An electronic device may include a first GPU and a second GPU and tangible computer-readable storage media defining instructions to detect connection of an external display through an adapter, determine if the first GPU is active, and switch to the first GPU to provide output to the external display if the first GPU is not active. The GPU power control process may detect connection of an adapter to the electronic device and read an indication of connection of an external display through the adapter. One of the GPUs of the electronic device may be activated based on the indication."

-- Dennis Sellers