Abstract: An electronic device may be provided with a display. The display may be a variable frame rate display capable of adaptively adjusting a frame rate at which display frames are displayed in response to information associated with the current state of operation of the device. The information may be gathered using control circuitry in the electronic device. The control circuitry may gather the information for adjusting the frame rate by monitoring the electronic device power supply configuration, other device components, the type of content to be displayed, and user-input signals. The control circuitry may adjust the frame rate based on the gathered information by increasing or decreasing the frame rate. The control circuitry may be formed as a portion of display control circuitry for the device such as a display driver integrated circuit or may be formed as a portion of storage and processing circuitry external to the display.

Abstract: An apparatus and method for encoding data are disclosed that may allow for performing periodic calibration operations on a communication link. A controller may determine multiple possible values for a reference voltage used with the communication link based on an initial value. Calibration operations may be performed using each possible value, and the results of the operations scored based on the width of data eyes measured during the calibration operations. The controller may then select a new value for the reference voltage from the multiple possible values dependent upon the scores of each of the multiple possible values.

Abstract: An electronic device may generate content that is to be displayed on a display. The display may have an array of liquid crystal display pixels for displaying image frames of the content. The image frames may be displayed with positive and negative polarities to help reduce charge accumulation effects. A charge accumulation tracker may analyze the image frames to determine when there is a risk of excess charge accumulation. The charge accumulation tracker may analyze information on gray levels, frame duration, and frame polarity. The charge accumulation tracker may compute a charge accumulation metric for entire image frames or may process subregions of each frame separately. When subregions are processed separately, each subregion may be individually monitored for a risk of excess charge accumulation.

Abstract: Systems, apparatuses, and methods for driving a split display with multiple display pipelines. Frames for driving a display are logically divided into portions, a first display pipeline drives a first portion of the display, and a second display pipeline drives a second portion of the display. Each display pipeline generates dither noise for each frame in its entirety but only utilizes dither noise for the portion of the frame which is being driven to its respective portion of the display. This approach prevents visual artifacts from appearing at the dividing line between the first and second portions of the display.

Abstract: An electronic device may generate content that is to be displayed on a display. The display may have an array of liquid crystal display pixels for displaying image frames of the content. The image frames may be displayed with positive and negative polarities to help reduce charge accumulation effects. A charge accumulation tracker may analyze the image frames to determine when there is a risk of excess charge accumulation. The charge accumulation tracker may analyze information on gray levels, frame duration, and frame polarity. The charge accumulation tracker may compute a charge accumulation metric for entire image frames or may process subregions of each frame separately. When subregions are processed separately, each subregion may be individually monitored for a risk of excess charge accumulation.

Abstract: Synchronization of display functions and various touch, stylus and/or force sensing functions for devices including a variable refresh rate (VRR) display is disclosed. In some examples, touch, stylus and/or force sensing functions can be synchronized with display frames and a display refresh rate can be adjusted by extended blanking of the display for one or more display frames. In other examples, touch, stylus and/or force sensing functions can be synchronized with display sub-frames and a display refresh rate can be adjusted by extended blanking of the display for one or more display sub-frames. Pre-warning synchronization signals can be generated to prepare one or more scan controllers to implement the appropriate scan events during and after extended blanking periods. Latency between the scan results and the corresponding image on the display can be corrected in software and/or firmware by time-stamping scan results or by dropping scan results from uncompleted scans.

Abstract: Embodiments of an apparatus for implementing a display port interface are disclosed. The apparatus may include a source processor and a sink processor coupled through an interface. The interface may include a primary link, an auxiliary link, and a hot plug detect link. The source processor may be operable to send a wake-up command to the sink processor via the auxiliary link. The source processor may send initialization parameters to the sink processor via the primary link. The initialization parameters may include a clock data recovery lock parameter and an idle parameter. Following the initialization parameters, the source processor may send a synchronization signal to the sink processor via the primary link. The source processor may then send a sleep command via the primary link to the sink processor.

Abstract: An interface emulator for an IC is disclosed. An interface emulator includes a first first-in, first-out memory (FIFO) and a second FIFO. The first FIFO is coupled to receive data from an access port and a second FIFO coupled to receive data from at least one functional unit in the IC. The access port may be coupled to a device that is external to the IC. The external device may write information into the first FIFO, and this information may subsequently be read by a functional unit in the IC. Similarly, the functional unit may write information into the second FIFO, with the external device subsequently reading the information. Information may be written into the FIFOs in accordance with a predefined protocol. Thus, a particular type of interface may be emulated even though the physical connection and supporting circuitry for that interface is not otherwise implemented in the IC.

Abstract: An interface emulator for an IC is disclosed. An interface emulator includes a first first-in, first-out memory (FIFO) and a second FIFO. The first FIFO is coupled to receive data from an access port and a second FIFO coupled to receive data from at least one functional unit in the IC. The access port may be coupled to a device that is external to the IC. The external device may write information into the first FIFO, and this information may subsequently be read by a functional unit in the IC. Similarly, the functional unit may write information into the second FIFO, with the external device subsequently reading the information. Information may be written into the FIFOs in accordance with a predefined protocol. Thus, a particular type of interface may be emulated even though the physical connection and supporting circuitry for that interface is not otherwise implemented in the IC.

Abstract: A graphics processing circuit and method for power savings in the same is disclosed. In one embodiment, a graphics processing circuit includes a number of channels. The number of channels includes a number of color component channels that are each configured to process color components of pixel values of an incoming frame of graphics information. The number of channels also includes an alpha scaling channel configured to process alpha values (indicative of a level of transparency) for the incoming and/or outgoing frames. The graphics processing circuit also includes a control circuit. The control circuit is configured to place the alpha scaling channel into a low-power state responsive to determining that at least one of the incoming or outgoing frames does not include alpha values.

Abstract: Systems, apparatuses, and methods for passing source pixel data through a display control unit. A display control unit includes N-bit pixel component processing lanes for processing source pixel data. When the display control unit receives M-bit source pixel components, wherein ‘M’ is greater than ‘N’, the display control unit may assign the M-bit source pixel components to the N-bit processing lanes. Then, the M-bit source pixel components may passthrough the pixel component processing elements of the display control unit without being modified.

Abstract: In an embodiment, a system on a chip (SOC) includes a component that remains powered when the remainder of the SOC is powered off. The component may include a sensor capture unit to capture data from various device sensors, and may filter the captured sensor data. Responsive to the filtering, the component may wake up the remainder of the SOC to permit the processing. The component may store programmable configuration data, matching the state at the time the SOC was most recently powered down, for the other components of the SOC, in order to reprogram them after wakeup. In some embodiments, the component may be configured to wake up the memory controller within the SOC and the path to the memory controller, in order to write the data to memory. The remainder of the SOC may remain powered down.

Abstract: An under voltage detection circuit and method of operating an IC including the same is disclosed. In one embodiment, an IC includes an under voltage protection circuit having first and second comparators configured to compare a supply voltage to first and second voltage thresholds, respectively, with the second voltage threshold being greater than the first. A logic circuit is coupled to receive signals from the first and second comparators. During operation in a high performance state by a corresponding functional circuit, the logic circuit is configured to cause assertion of a throttling signal responsive to an indication that the supply voltage has fallen below the first threshold. A clock signal provided to the functional circuit may be throttled responsive to the indication. If the supply voltage subsequently rises to a level above the second threshold, the throttling signal may be de-asserted.

Abstract: Systems, apparatuses, and methods for adjusting the frame refresh rate used for driving frames to a display. A display pipeline is configured to drive a display using a reduced frame refresh rate in certain scenarios. The reduced frame refresh rate may be specified in frame packets which contain configuration data for processing corresponding frames. The display pipeline may drive idle frames to the display to generate the reduced frame refresh rate. When a touch event is detected, the display pipeline may override the reduced frame refresh rate and instead utilize a standard frame refresh rate until all of the frames corresponding to stored frame packets have been processed.

Abstract: In an embodiment, a host computing device includes an internal display and also includes a connector to connect to an external display. A cable is provided to connect to the connector and to connect to the external display. The cable includes video processing capabilities. For example, the cable may include a memory configured to store a frame buffer. The frame buffer may store a frame of video data for further processing by the video processing device in the cable. The video processing device may manipulate the frame in a variety of ways, e.g. scaling, rotating, gamma correction, dither correction, etc.

Abstract: Systems, apparatuses, and methods for synchronizing backlight adjustments to frame updates in a display pipeline. A change in the ambient light is detected and as a result, backlight settings are adjusted. To offset a reduction in the backlight, the color intensity in the frames is increased. While the change in ambient light is detected asynchronously, the adjustment to the backlight settings and color intensity is synchronized to a frame update via a virtual channel for the auxiliary channel of the display interface.

Abstract: In an embodiment, a system on a chip (SOC) includes a component that remains powered when the remainder of the SOC is powered off. The component may include a sensor capture unit to capture data from various device sensors, and may filter the captured sensor data. Responsive to the filtering, the component may wake up the remainder of the SOC to permit the processing. The component may store programmable configuration data, matching the state at the time the SOC was most recently powered down, for the other components of the SOC, in order to reprogram them after wakeup. In some embodiments, the component may be configured to wake up the memory controller within the SOC and the path to the memory controller, in order to write the data to memory. The remainder of the SOC may remain powered down.

Abstract: Devices and methods for reducing and/or substantially eliminating pixel charge imbalance due to variable refresh rates are provided. By way of example, a method includes providing a first frame of image data via a processor to a plurality of pixels of the display during a first frame period corresponding to a first refresh rate, and providing a second frame of image data to the plurality of pixels of the display during a second frame period corresponding to a second refresh rate. The method further includes dividing the first frame period into a first frame sub-period and a second frame sub-period, and driving the plurality of pixels of the display with the first frame of image data during the first frame sub-period and the second frame sub-period.

Abstract: Systems, apparatuses, and methods for implementing a timestamp based display update mechanism. A display control unit includes a timestamp queue for storing timestamps, wherein each timestamp indicates when a corresponding frame configuration set should be fetched from memory. At pre-defined intervals, the display control unit may compare the timestamp of the topmost entry of the timestamp queue to a global timer value. If the timestamp is earlier than the global timer value, the display control unit may pop the timestamp entry and fetch the frame next configuration set from memory. The display control unit may then apply the updates of the frame configuration set to its pixel processing elements. After applying the updates, the display control unit may fetch and process the source pixel data and then drive the pixels of the next frame to the display.

Abstract: A method and device for data compression are presented, in which a data processor may receive a packet of image data which includes four groups of N bits, where N is an integer greater than 2. The data processor may compress the received packet of data, such that a total number of bits for the converted packet is less than four times N. The data processor may compress the received packet of image data by reducing the resolution of three of the values while maintaining the resolution of the fourth value. To reduce the resolution of the three values, the data processor may apply a dithering formula to the values. The data processor may then send the converted packet via an interface.