Debugger recovery on exit from low power mode
View Patent ↗A device is configured with components to enable debugging of the device's entry into and exit from a low power mode. The device includes: core logic, debug components, and a power management module (PMM). When the device exits a low power mode in which the states of the debug components are lost, the PMM prevents the core logic from resuming processing operations until the debug components have been re-configured to their prior states. The PMM either holds the core logic in reset or alternatively withholds power to the core logic. Reconfiguration of the debug components is initiated by a connected debugger, which can set one or more control and status (CS) register values within the device. The CS register values determine when the PMM prevents the core logic processing from resuming and when the PMM enables core logic processing to resume following the device's return from low power mode.
1. A device configured to enable debugging of a return by the device from a low power mode state, the device comprising:
a first set of components that process instructions and performs functional operations of the device;
a second set of components that facilitates debugging operations of the device and which maintain one or more current debug states while receiving power;
a power management module (PMM) having PMM logic that in response to receiving an input to activate a return of the device from a low power state in which power was removed from the first set of components and the second set of components: determines a type of low power mode from which the device is returning, where the type is one of a plurality of different types of low power modes; and in response to the device returning from a first type low power mode in which the current debug states of the second set of components are lost, prevents one or more of the first set of components from resuming processing operations until the second set of components have been re-configured to their respective current debug states;
wherein the PMM logic further: detects an entry of the device into the low power mode; automatically asserts a reset signal to the first set of components in response to detecting the device's entry into the low power mode; continues to assert the reset signal in response to the device returning from the first type low power mode; receives an input indicating an assertion of the reset signal is no longer required; and automatically negates the reset signal to enable the first set of components to resume processing, in response to receiving the input indicating the assertion of the reset signal is no longer required.
2. The device of claim 1 , wherein:
the PMM comprises a power allocation mechanism for granularly applying power to the first set of components, separate and independent from applying power to the second set of components; and
in response to a return from a first type low power mode, the PMM logic: immediately applies power to the second set of components; and delays an application of power to the first set of components until receipt of the input indicating that the second set of components have been re-configured to their respective current debug states.
3. The device of claim 1 , wherein the PMM logic prevents one or more of the first set of components from resuming processing operations until the second set of components have been re-configured to their respective current debug states by withholding allocation of clock cycles to the one or more first set of components.
4. A device configured to enable debugging of a return by the device from a low power mode state, the device comprising:
a first set of components that process instructions and performs functional operations of the device;
a second set of components that facilitates debugging operations of the device and which maintain one or more current debug states while receiving power;
a power management module (PMM) having PMM logic that in response to receiving an input to activate a return of the device from a low power state in which power was removed from the first set of components and the second set of components: determines a type of low power mode from which the device is returning, where the type is one of a plurality of different types of low power modes; and in response to the device returning from a first type low power mode in which the current debug states of the second set of components are lost, prevents one or more of the first set of components from resuming processing operations until the second set of components have been re-configured to their respective current debug states;
one or more control and status (CS) registers having: a first entry that is settable to a first value, which indicates a debug of the device's entry and exit from a low power mode is to be performed; and a second entry that is settable to a second value, which indicates to the PMM logic that the one or more first set of components can be allowed to resume processing operations.
5. The device of claim 4 , wherein the PMM logic further: detects an entry of the device into the low power mode; automatically asserts a reset signal to the first set of components in response to detecting the device's entry into the low power mode; continues to assert the reset signal in response to the device returning from the first type low power mode; receives an input indicating an assertion of the reset signal is no longer required; and automatically negates the reset signal to enable the first set of components to resume processing, in response to receiving the input indicating the assertion of the reset signal is no longer required.
6. The device of claim 5 , wherein the one or more CS registers comprise: a third entry that is settable by the PMM logic to a third value, which indicates that the low power mode was a first type low power mode; and a fourth entry that is settable by the PMM logic to a fourth value, which indicates that the low power mode was a second type low power mode.
7. The device of claim 6 , wherein: the one or more CS registers are located within the PMM; the value within the first entry is set/reset by receipt of signals from a debugger; and the value within the second entry is set by the receipt of a signal from the debugger and reset by one of the PMM logic and the debugger following resumption of processing operations by the first set of components.
8. The device of claim 6 , wherein:
the one or more CS registers are coupled to the PMM via one or more signal lines;
the PMM comprises a latch; and
in response to detection of an entry by the device into the low power mode, the PMM logic latches into the latch a current value of a first entry of the CS register; checks a latched value saved within the latch, in response to a return of the device from the low power mode; and in response to the latched value being a first value: withholds a negation of a reset signal to the first set of components, wherein the negation of the reset signal is required to enable the first set of components to enter into an operational state; detects a current value of the second entry of the one or more CS registers; and negates the reset signal to the first set of components, in response to the current value associated with the second entry being the second value.
9. A device configured to enable debugging of a return by the device from a low power mode state, the device comprising:
a first set of components that process instructions and performs functional operations of the device;
a second set of components that facilitates debugging operations of the device and which maintain one or more current debug states while receiving power;
a power management module (PMM) having PMM logic that in response to receiving an input to activate a return of the device from a low power state in which power was removed from the first set of components and the second set of components: determines a type of low power mode from which the device is returning, where the type is one of a plurality of different types of low power modes; and in response to the device returning from a first type low power mode in which the current debug states of the second set of components are lost, prevents one or more of the first set of components from resuming processing operations until the second set of components have been re-configured to their respective current debug states;
a power supply connection for receiving power for powering the device;
one or more control and status (CS) registers having a plurality of entries utilized to enable debugging of a return of the device from a low power mode; and
a communication interface that enables communication by an external debugger with the device, wherein the external debugger is communicatively coupled to the second set of components and to one or more CS registers to enable the external debugger to: exchange debug information with the second set of components; set a value of one or more entries of the CS register; receive one or more values from one or more entries of the CS register; and restore state of the second set of components to the current debug state that existed prior to entry of the device into a first type low power mode.
10. The device of claim 9 , wherein the PMM logic further: detects an entry of the device into the low power mode; automatically asserts a reset signal to the first set of components in response to detecting the device's entry into the low power mode; continues to assert the reset signal in response to the device returning from the first type low power mode; receives an input indicating an assertion of the reset signal is no longer required; and automatically negates the reset signal to enable the first set of components to resume processing, in response to receiving the input indicating the assertion of the reset signal is no longer required.
11. The device of claim 9 , wherein the one or more CS registers include: a first entry that is settable to a first value, which indicates a debug of the device's entry and exit from a low power mode is to be performed; and a second entry that is settable to a second value, which indicates to the PMM logic that the one or more first set of components can be allowed to resume processing operations.
12. The device of claim 9 , wherein the PMM logic determines when a low power mode from which the device is exiting is a first type low power state that requires a restore of one or more debugs components among the second set of components to enable seamless resumption of debugging operations on the device to capture debug data covering the exit by the device from the low power mode; and in response to the low power mode being the first type low power mode, automatically sets a value of a third entry of the CS register to indicate that the low power mode was a first type low power mode to trigger a hold of a negation of the reset of the device; wherein the hold on the negation of the reset enables the external debugger to first restore the one or more debug components to the before the reset signal is negated by the PMM logic.
13. A device configured to enable debugging of a return by the device from a low power mode state, the device comprising:
a first set of components that process instructions and performs functional operations of the device;
a second set of components that facilitates debugging operations of the device and which maintain one or more current debug states while receiving power;
a power management module (PMM) having PMM logic that in response to receiving an input to activate a return of the device from a low power state in which power was removed from the first set of components and the second set of components: determines a type of low power mode from which the device is returning, where the type is one of a plurality of different types of low power modes; and in response to the device returning from a first type low power mode in which the current debug states of the second set of components are lost, prevents one or more of the first set of components from resuming processing operations until the second set of components have been re-configured to their respective current debug states;
wherein the PMM logic determines when a low power mode from which the device is exiting is a first type low power state that requires a restore of one or more debugs components among the second set of components to enable seamless resumption of debugging operations on the device to capture debug data covering the exit by the device from the low power mode; and in response to the low power mode being the first type low power mode, automatically sets a value of a third entry of a control and status (CS) register to indicate that the low power mode was a first type low power mode to trigger a hold of a negation of the reset of the device; wherein the hold on the negation of the reset enables the external debugger to first restore the one or more debug components to the before the reset signal is negated by the PMM logic.
14. The device of claim 13 , wherein the PMM logic further: detects an entry of the device into the low power mode; automatically asserts a reset signal to the first set of components in response to detecting the device's entry into the low power mode; continues to assert the reset signal in response to the device returning from the first type low power mode; receives an input indicating an assertion of the reset signal is no longer required; and automatically negates the reset signal to enable the first set of components to resume processing, in response to receiving the input indicating the assertion of the reset signal is no longer required.
15. The device of claim 13 , wherein the one or more CS registers include: a first entry that is settable to a first value, which indicates a debug of the device's entry and exit from a low power mode is to be performed; and a second entry that is settable to a second value, which indicates to the PMM logic that the one or more first set of components can be allowed to resume processing operations.
16. The device of claim 13 , further comprising:
a power supply connection for receiving power for powering the device; and
a communication interface that enables communication by an external debugger with the device, wherein the external debugger is communicatively coupled to the second set of components and to the one or more CS registers having a plurality of entries utilized to enable debugging of a return of the device from a low power mode, and which enables the external debugger to: exchange debug information with the second set of components; set a value of one or more entries of the CS register; receive one or more values from one or more entries of the CS register; and restore state of the second set of components to the current debug state that existed prior to entry of the device into a first type low power mode.
17. A computer implemented method for debugging, via a debugger application, a device configured with a power management module (PMM), one or more debug components and a plurality of control and status (CS) registers, which are communicatively accessible to the debugger application, the method comprising:
transmitting, via a connection to the device, a first command which sets a value of a first entry of the plurality of CS registers to a first value, wherein the first value indicates that a debugging session being performed on the device should include a debug of an exit by the device from a first type low power mode;
wherein setting the value to the first value causes the PMM to prevent one or more core logic of the device to not resume operations following an exit of the device from the first type low power mode;
periodically receiving debug session data and state information from the one or more debug components on the device and one or more of the plurality of CS registers;
responsive to receiving information indicating that the device has entered into the low power mode, suspending transmission of debug commands to the device;
responsive to receiving information indicating that the device has exited from a second type low power mode, resuming the debug session for the device without initiating reconfiguration of the one or more debug components; and
responsive to receiving information indicating that the device has exited from the first type low power mode, transmitting information to the device to re-configure the one or more debug components to respective debug states existing prior to entry of the device into the first type low power mode.
18. The computer implemented method of claim 17 , further comprising:
in response to completion of a reconfiguration of the one or more debug components following an exit by the device from the first type low power mode:
resuming the debug session for the device; and
transmitting to the device a second command, which sets a second value of a second entry of the plurality of CS registers to a second value, wherein the second value indicates to the PMM that the reconfiguration of the debug components is complete and wherein the PMM responds to detection of the second value within the second entry of the CS registers by enabling the one or more core logic to resume processing operations.
19. The computer implemented method of claim 17 , further comprising:
detecting a loss of communication with the device during an ongoing debug session;
suspending the debug session while the loss of communication continues;
when communication is re-established with the device, receiving next information from the device;
identifying from the received next information that the loss of communication was due to entry of the device into a low power mode;
determining whether the low power mode is a first type low power mode, where the first type low power mode is one of a plurality of different types of low power modes; and
in response to the low power mode being a first type low power mode, initiating the transmitting to the device of the second command.
20. The computer implemented method of claim 17 , further comprising:
in response to the debugger application receiving debug session data and state information after the device has exited from a low power mode, tagging the received data and state information as being associated with the exit from the low power mode, wherein the debugger application is able to identify which debug data corresponds to the device exiting the low power mode.
21. The computer implemented method of claim 17 , wherein:
the first entry is an exit hold reset enable (EHRE) bit and the first command is a signal which sets the EHRE bit to a logic 1 value;
the second entry is an exit hold reset release (EHRR) bit and the second command is a signal which sets the EHRR bit to a logic 1 value; and
setting of the EHRR bit triggers the PMM to perform one or more functions from among: (a) when the PMM withholds power from the one or more core logic on exit from the low power mode until the EHRR bit is set to the logic 1 value, applying power to the one or more core logic to enable the core logic to resume processing operations of the device; and (b) when the PMM asserts a reset signal to the one or more core logic on exit of the device from the low power mode and continues to assert the reset signal until the EHRR bit is set to the logic 1 value, negating an assertion of the reset signal to enable the one or more core logic to resume processing operations of the device.
22. In a device configured with one or more core logic and one or more debug components to facilitate debug operations of the device, and one or more control and status (CS) registers, a method for enabling debugging of a low power mode entry and exit by the device, the method comprising:
in response to receiving an input to activate a return of the device from a low power mode in which power was removed from the core logic as well as the one or more debug components:
determining a type of low power mode from which the device is returning, where the type is one of a plurality of different types of low power modes; and
in response to the device returning from a first type low power mode in which the current debug states of the one or more debug components are lost, preventing one or more of the core logic from resuming processing operations until the one or more debug components have been re-configured to their respective debug states;
detecting an entry of the device into the low power mode;
in response to detecting the device's entry into the low power mode, automatically asserting a reset signal to the core logic;
continuing to assert the reset signal in response to the device returning from the first type low power mode;
receiving an input indicating an assertion of the reset signal is no longer required; and
in response to receiving the input indicating the assertion of the reset signal is no longer required, automatically negating the reset signal to enable the core logic to resume processing.
23. The method of claim 22 , wherein the PMM comprises a power allocation mechanism for granularly applying power to the first set of components, separate and independent from applying power to the second set of components, and the method further comprises:
responsive to a return from a first type low power mode:
immediately applying power to the second set of components; and
delaying an application of power to the first set of components until receipt of the input indicating that the second set of components have been re-configured to their respective current debug states.
24. In a device configured with one or more core logic and one or more debug components to facilitate debug operations of the device, and one or more control and status (CS) registers, a method for enabling debugging of a low power mode entry and exit by the device, the method comprising:
in response to receiving an input to activate a return of the device from a low power mode in which power was removed from the core logic as well as the one or more debug components:
determining a type of low power mode from which the device is returning, where the type is one of a plurality of different types of low power modes; and
in response to the device returning from a first type low power mode in which the current debug states of the one or more debug components are lost, preventing one or more of the core logic from resuming processing operations until the one or more debug components have been re-configured to their respective debug states;
wherein the one or more CS registers comprises: a first entry that is settable to a first value, which indicates a debug of the device's entry and exit from a low power mode is to be performed; a second entry that is settable to a second value, which indicates to the PMM logic that the core logic can be allowed to resume processing operations; a third entry that is settable by the PMM logic to a third value, which indicates that the low power mode was a first type low power mode; and a fourth entry that is settable by the PMM logic to a fourth value, which indicates that the low power mode was a second type low power mode;
wherein the one or more CS registers are coupled to the PMM via one or more signal lines and the PMM comprises a latch; and
in response to detection of an entry by the device into the low power mode, latching into the latch a current value of a first entry of the CS register;
in response to a return of the device from the low power mode, checking a latched value saved within the latch;
in response to the latched value being a first value and the PMM preventing the core logic from processing by assertion of a reset signal:
withholding a negation of a reset signal to the core logic, wherein the negation of the reset signal is required to enable the core logic to enter into an operational state;
determining when a low power mode from which the device is exiting is a first type low power state that requires a restore of one or more debugs components to enable seamless resumption of debugging operations on the device to capture debug data covering the exit by the device from the low power mode; and in response to the low power mode being the first type low power mode, automatically setting a value of a third entry of the CS register to indicate that the low power mode was a first type low power mode to trigger a hold of a negation of the reset of the device; and
detecting a current value of the second entry of the one or more CS registers; and responsive to the current value associated with the second entry being the second value, negating the reset signal to core logic;
wherein the withholding of the negation of the reset enables the external debugger to first restore the one or more debug components to the before the reset signal is negated by the PMM logic; and
wherein each change to the first entry and the second entry of the CS register is received via a communication interface that enables communication by an external debugger with the device, wherein the external debugger is communicatively coupled to the second set of components and to one or more CS registers to enable the external debugger to: exchange debug information with the second set of components; set a value of one or more entries of the CS register; receive one or more values from one or more entries of the CS register; and restore state of the second set of components to the current debug state that existed prior to entry of the device into a first type low power mode.
25. The method of claim 24 , further comprising:
detecting an entry of the device into the low power mode;
in response to detecting the device's entry into the low power mode, automatically asserting a reset signal to the core logic;
continuing to assert the reset signal in response to the device returning from the first type low power mode;
receiving an input indicating an assertion of the reset signal is no longer required; and
in response to receiving the input indicating the assertion of the reset signal is no longer required, automatically negating the reset signal to enable the core logic to resume processing.