Patent Application
20230099399
During a power saving mode in a system on chip (SOC) computer system, it is possible that a device may wake the SOC out of the power saving mode. There are numerous external devices in communication with the SOC that include their own embedded controllers (ECs). If those ECs send a signal to the SOC, it could prematurely wake the SOC from the power saving state. On the other hand, the ECs need to be placed in the lower power state as well to maximize the platform level power savings.
A more detailed understanding can be had from the following description, given by way of example in conjunction with the accompanying drawings wherein:
Although the method and apparatus will be expanded upon in further detail below, briefly a method for managing a controller in a power-down state is described. When a system on chip (SOC) enters a power-down state, it signals to embedded controllers (ECs) in devices connected to the SOC to enter the power-down state as well so as not to prematurely wake the SOC from the power-down state. Once the power-down state is exited, the ECs are revived.
For example, in an SOC computer system, in order to effect power savings, some areas associated with the SOC may be powered down for power savings. However, components such as an on-platform device (PLD) or BMC (baseboard management controller), or the like, may continue to be powered up. Accordingly, the ECs in those devices may remain active if not instructed otherwise. Although described in additional detail below, an SOC is a device where many components of an entire system are resident on a chip. For example, an SOC may include a processor, memory, storage, input and output drivers, and other components on a single chip
A method for managing a controller includes indicating, by a processor of a first device, to the controller of a second device to enter a second power state from a first power state. The controller of the second device responds to the processor of the first device with a confirmation. The processor of the first device transmits a signal to the controller of the second device to enter the second power state. Upon receiving a wake event, the controller of the second device exits the second device from the second power state to the first power state.
A system for managing a controller includes a system on chip (SOC) processor and an embedded controller (EC) integrated on an external device to the SOC, the EC operatively coupled with and in communication with the SOC processor. The SOC processor indicates to the EC to enter a second power state for the external device from a first power state. The EC responds to the SOC processor with a confirmation. The SOC processor transmits a signal to the EC to enter the second power state, and upon receiving a wake event, the EC exits the second power state to the first power state.
A non-transitory computer-readable medium for managing a controller, the non-transitory computer-readable medium having instructions recorded thereon, that when executed by the processor, cause the processor to perform operations. The operations include indicating, by a processor of a first device, to the controller of a second device to enter a second power state from a first power state. The controller of the second device responds to the processor of the first device with a confirmation. The processor of the first device transmits a signal to the controller of the second device to enter the second power state. Upon receiving a wake event, the controller of the second device exits the second device from the second power state to the first power state.
The device 100 can also optionally include an input driver 112 and a driver 114 if a device 110 requires a driver. Additionally, the device 100 includes a memory controller 115 that communicates with the processor 102 and the memory 104, and also can communicate with an external memory 116. In some embodiments, memory controller 115 will be included within processor 102. It is understood that the device 100 can include additional components not shown in
As discussed above, the processor 102, memory 104, storage 106, input driver 112, output driver 114 and memory controller 115 may be included on an SOC 101.
In various alternatives, the processor 102 includes a central processing unit (CPU), a graphics processing unit (GPU), a CPU and GPU located on the same die, or one or more processor cores, wherein each processor core can be a CPU or a GPU. In various alternatives, the memory 104 is located on the same die as the processor 102, or is located separately from the processor 102. The memory 104 includes a volatile or non-volatile memory, for example, random access memory (RAM), dynamic RAM, or a cache.
The storage 106 includes a fixed or removable storage, for example, a hard disk drive, a solid state drive, an optical disk, or a flash drive. The input devices 108 include, without limitation, a keyboard, a keypad, a touch screen, a touch pad, a detector, a microphone, an accelerometer, a gyroscope, a biometric scanner, or a network connection (e.g., a wireless local area network card for transmission and/or reception of wireless IEEE 802 signals). The output devices 110 include, without limitation, a display, a speaker, a printer, a haptic feedback device, one or more lights, an antenna, or a network connection (e.g., a wireless local area network card for transmission and/or reception of wireless IEEE 802 signals).
The input driver 112 communicates with the processor 102 and the input devices 108, and permits the processor 102 to receive input from the input devices 108. The output driver 114 communicates with the processor 102 and the output devices 110, and permits the processor 102 to send output to the output devices 110. It is noted that the input driver 112 and the output driver 114 are optional components, and that the device 100 will operate in the same manner if the input driver 112 and the output driver 114 are not present.
The external memory 116 may be similar to the memory 104, and may reside in the form of off-chip memory. Additionally, the external memory may be memory resident in a server where the memory controller 115 communicates over a network interface to access the external memory 116.
Each of the ECs 230 is in communication with the SOC 101 (e.g., via the processor 102). The ECs 230 are, in some embodiments, microcontrollers that process information and execute operation for a device independent of the processor 102 and SOC 101. For example, an EC 230 may perform the function of processing signals to and from a keyboard, a touchpad, an onboard battery, and the like, as well as PCIe devices connected to the system 200.
By utilizing ECs, firmware can be updated for devices and the devices can be controlled without an operating system controlling it. This may free resources for the operating system and the SOC 101 to perform other tasks. Accordingly, the devices 110 controlled by ECs 230 operate independently of the SOC 101.For example, the devices 110 controlled by the ECs 230 may include ECs 230 for an on-platform device (PLD) or BMC (baseboard management controller). However, it should be noted that other devices 110 that include ECs may be connected to the SOC 101.
To guarantee both and SOC and EC components remain in the low power state uninterrupted for as long a time as possible, an SOC to EC protocol is utilized to conduct signaling. In fact, even when an EC is woken up and needs to wake up the SOC, an internal EC protocol allows for queuing more than single event before triggering the SOC wake-up.
In order to depict the signaling between the SOC and the ECs with regard to managing the ECs,
Referring now to
For example, referring back to
This signal 310 may be transmitted over a virtual wire, which is a logical connection between two endpoints. That is, rather than a physical wire connecting two devices (e.g., SOC 101 and ECs 230), a logical connection which may be routed through additional points exists. In a wired solution, a physical wire exists to transmit information between components. It should be noted that in other embodiments, a direct wire or firmware message can provide this indication.
In step 430 the ECs respond to the SOC. Again, referring back to
Again, this response signal 320 may be transmitted over the same virtual wire that the first signal 310 is transmitted over. Alternatively, it may be transmitted over a different virtual wire or a physical wire.
After waiting a pre-defined period of time, the SOC 101 sends an enter low power signal 330 to the ECs to enter the low power mode. The enter low power mode signal 330 may also be transmitted over the same virtual wire that the first signal 310 and the response signal 320 are transmitted over. Alternatively, it may be transmitted over a different virtual wire or a physical wire. The ECs 230 then enter the power-down/low power state and arm themselves for a wake function (step 440).
In this manner, the ECs 230 enter a low power mode and then wait for a wake up message. The low power mode can be several levels of low power. For example, the low power mode could be a battery saving mode that is a maximum power saving mode or a lower power saving mode.
For example, the lower power savings mode is a power mode where the ECs operate with only an amount of power to achieve minimal functionality. In some embodiments, it may be power just to keep circuitry operating that may be utilized to wake once receiving a wake signal, discussed below. That is, some EC initiated operations can be fully disabled or their rate of use is substantially reduced when the SOC is in the power-down mode. For example, for an EC that controls a fan in the system, the polling of the thermal sensor, which provides information to that EC as to when to turn the fan on to cool the system may occur less frequently.
The SOC will be in the power-down mode for a period of time before needing to wake up. The period of time can be preconfigured or dynamically determined. For example, the period of time may before the SOC needs to wake up may depend on a hysteresis or event tracker.
In particular, one technique for waking up the SOC may be via a hysteresis or event tracker that is used to qualify the SOC for wake-up when the tracker exceeds some predefined values. The hysteresis defines how long every type of wake-up event is expected to wait before proceeding to wake up the SOC from the low power state Also, as mentioned, event may be tracked, such as battery power level, and if the event being tracked exceeds the predefined value (e.g., a battery level drops below a predefined value), a wake up is triggered.
Alternatively, the operation may be utilized in the opposite direction. That is, the SOC wakes up the EC after qualifying a need for the EC to be in operation. As indicated above, the determining whether the SOC to wake up the EC can be preconfigured or determined dynamically. In an example, one technique for waking up the EC may be via an event tracker. For example, an event tracker is set and the SOC wakes up the EC when the event tracker exceeds the predefined value.
For example, if an operation is required that the device controlled by the EC performs, the SOC may determine that the EC should be awakened and send a signal that will wake the EC. If the event tracker does not exceed the predefined value, the SOC can extend the EC low power state by tracking the wake-up events until the predefined value is exceeded.
If the ECs do not receive a transaction from the SOC (step 450), then they remain in the low power mode. If the ECs receive a transaction from the SOC (step 450), then the ECs exit the power-down state in step 460. Also, the ECs may exit the power power-down state if an event occurs such as a keyboard strike, a mouse touch, or the battery drain falls below a threshold amount.
For example, as mentioned above, if the SOC determines that an operation is needed from a device that an EC controls, the SOC will send a transaction signal discussed below, to that EC to wake.
Referring back to
In another embodiment, the ECs may wake up to the full operational state in a periodic manner based on the timer, and then be put back into the low power state if no activity requiring EC occurs.
For example, the SOC 210 may send a transaction signal that relates to an operation required to be executed by that EC 230. As mentioned above, the EC 230 may be resident on an on-platform device (PLD) or BMC (baseboard management controller) that is connected to the SOC to perform operations.
In accordance with the above description, external devices to the SOC that include embedded controllers are prevented from sending signals to the SOC, potentially prematurely waking the SOC and interfering with power savings. The ECs are also put into a power saving mode and armed for waking upon an event taking place. In one example, the event is any transaction that occurs from the SOC.
Additionally, although the examples described above discusses a single EC, there are other embodiments where an SOC can interact with more than one EC or with other on-platform devices (i.e., PLDs). For example, as described above, an SOC can interact with an EC that is utilized to control the temperature control of the system.
However, even where there may be more than single on-platform device, the protocol/handshake is identical to the one that is described in this application.
As discussed, the above description relates to when an SOC is entering a power-down state in order to effect power savings.
When the EC triggers the SOC wake-up, only a limited portion of the SOC may power up and the reason/need for a more extended wake-up is analyzed. This analysis may include accessing the EC internal log/status registers to understand the reason for the SOC wake-up.
For example, some areas of the SOC that are required for battery control or thermal control may wake up depending on the requirements. However, if the SOC determines that additional areas of the SOC are required to wake-up (e.g., a display region circuitry), based on, for example, a need to alert a user on the screen to an event, those areas may wake in addition.
In another example, based on this check, the extent of a further wake-up of the SOC is identified. For example, it may be analyzed whether the wake up and SOC to EC interaction needs to be limited to on-die IO domain microcontroller or CPU/GPU cores need to be woken up. As mentioned above, should the display be determined as necessary, the GPU cores may be woken up in order to execute any necessary graphics processing.
In another example, the EC trigger/interface is accounted for on the SOC entry into the low power state only. Once in the low power state, the SOC may ignore the trigger or wake-up events coming from the EC. That is, the SOC may determine that a wake-up is not necessary even though the EC attempts to trigger the wake-up. For example, the SOC may receive a trigger from the EC (e.g., a thermal sensor), but due to battery power determine to maintain the low power state to maintain power savings.
The methods provided can be implemented in a general purpose computer, a processor, or a processor core. Suitable processors include, by way of example, a general purpose processor, a purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) circuits, any other type of integrated circuit (IC), and/or a state machine. Such processors can be manufactured by configuring a manufacturing process using the results of processed hardware description language (HDL) instructions and other intermediary data including netlists (such instructions capable of being stored on a computer readable media). The results of such processing can be maskworks that are then used in a semiconductor manufacturing process to manufacture a processor which implements features of the disclosure. Further, although the methods and apparatus described above are described in the context of controlling and configuring PCIe links and ports, the methods and apparatus may be utilized in any interconnect protocol where link width is negotiated.
The methods or flow charts provided herein can be implemented in a computer program, software, or firmware incorporated in a non-transitory computer-readable storage medium for execution by a general purpose computer or a processor. Examples of non-transitory computer-readable storage mediums include a read only memory (ROM), a random access memory (RAM), a register, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks, and digital versatile disks (DVDs). For example, the methods described above may be implemented in the processor 102 or on any other processor in the computer system 100. In addition, for example, the methods, or aspects thereof, described above may be performed by either a processor in the SOC or the EC.
