Abstract: Aspects of the embodiments are directed to systems, methods, and devices for controlling power management entry. A PCIe root port controller can be configured to receive, at a downstream port of the root port controller, from an upstream switch port, a first power management entry request; reject the first power management entry request; transmit a negative acknowledgement message to the upstream switch port; initiate a timer for at least 20 microseconds; during the 20 microseconds, ignore any power management entry requests received from the upstream switch port; receive, after the expiration of the 20 microseconds, a subsequent power management entry request; accept the subsequent power management entry request; and transmit an acknowledgement of the acceptance of the subsequent power management entry request to the upstream switch port.

Abstract: Aspects of the embodiments are directed to systems, methods, and devices for controlling power management entry. A PCIe root port controller can be configured to receive, at a downstream port of the root port controller, from an upstream switch port, a first power management entry request; reject the first power management entry request; transmit a negative acknowledgement message to the upstream switch port; initiate a timer for at least 20 microseconds; during the 20 microseconds, ignore any power management entry requests received from the upstream switch port; receive, after the expiration of the 20 microseconds, a subsequent power management entry request; accept the subsequent power management entry request; and transmit an acknowledgement of the acceptance of the subsequent power management entry request to the upstream switch port.

Abstract: Aspects of the embodiments are directed to systems, methods, and apparatuses for controlling power management states using a clock request message across a 3.3 volt GPIO pin. Systems can include a CPU root port to transmit to a platform controller hub (PCH) compliant with a PCIe protocol, a first clock request message, the first clock request message comprising a first bit set to assert a clock request transmit (CLKREQ TX assert) on a 3.3 volt general purpose input/output (GPIO) pin local to the PCH; detect that a connected device is entering into a power management state; and transmit, from the CPU root port, to the PCH, a second clock request message, the second clock request message comprising the first bit set to deassert the clock request transmit (CLKREQ TX deassert) and a second bit to assert a clock request protocol (CLKREQ#) on a 3.3 volt GPIO pin.

Abstract: Aspects of the embodiments are directed to systems, methods, and devices for controlling power management entry. A PCIe root port controller can be configured to receive, at a downstream port of the root port controller, from an upstream switch port, a first power management entry request; reject the first power management entry request; transmit a negative acknowledgement message to the upstream switch port; initiate a timer for at least 20 microseconds; during the 20 microseconds, ignore any power management entry requests received from the upstream switch port; receive, after the expiration of the 20 microseconds, a subsequent power management entry request; accept the subsequent power management entry request; and transmit an acknowledgement of the acceptance of the subsequent power management entry request to the upstream switch port.

Abstract: Aspects of the embodiments are directed to systems, methods, and apparatuses for controlling power management states using a clock request message across a 3.3 volt GPIO pin. Systems can include a CPU root port to transmit to a platform controller hub (PCH) compliant with a PCIe protocol, a first clock request message, the first clock request message comprising a first bit set to assert a clock request transmit (CLKREQ TX assert) on a 3.3 volt general purpose input/output (GPIO) pin local to the PCH; detect that a connected device is entering into a power management state; and transmit, from the CPU root port, to the PCH, a second clock request message, the second clock request message comprising the first bit set to deassert the clock request transmit (CLKREQ TX deassert) and a second bit to assert a clock request protocol (CLKREQ#) on a 3.3 volt GPIO pin.