Redpine Signals RS9116, Справочное руководство

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RS9116 n-Link Linux and Android Technical Reference Manual
Version : 2.0
July 2020
91
15 Power save Modes, Profiles and Parameters
The Power save modes and parameters are valid only for the Client mode. By default, the module's power save is
disabled.
15.1 Power save Modes
The module broadly supports two types of power save modes. They are outlined below:
• Low Power (LP) Mode: The PHY (RF and Baseband) and LMAC sections are powered off but the UMAC and
Host Interface sections of the module are powered on and fed a low frequency clock. The module responds
to commands/requests from the Host processor immediately in this mode.
• Ultra-low Power (ULP) Mode: A majority of the module is powered off except for a small section which has
a timer and interrupts logic for waking up the module. The module cannot respond to the Host processor's
commands/requests unless and until it gets wake up because of timeout or because of an interrupt asserted
by Host processor. The sleep entry/exit procedures in this mode are indicated to the Host processor either
through a packet based or signal based handshake. This mode is supported only for SDIO host interface.
15.2 Power save Profiles
For each of the above power save modes, the module supports multiple power save profiles. They are outlined
below:
• Deep Sleep: The module is in deep sleep mode when it is not connected to an Access Point. The duration of
the Deep Sleep is defined by the <sleep_duration> parameter of the set_ps_params command. For LP mode,
a value of 0 for the <sleep_duration> parameter programs the module to be in Deep Sleep mode indefinitely
till it is woken up by the Host processor via the host interface. The value of 0 is invalid for ULP mode and
should not be used.
• Connected Power Save : In the connected state, the module can operate in Traffic Based Power Save Profile
(PSP) or Fast PSP. These profiles are used by the module to decide when to enter and exit from power save
modes on the fly. They have to be selected based on the performance and power consumption
requirements of the end product.
• Traffic Based PSP : This profile is dependent on the <tx_threshold> and <rx_threshold> parameters, which
indicate transmit and receive throughput thresholds beyond which the module exits power save mode and
below which the module enters power save mode. The <tx_hysteresis> and <rx_hysteresis> parameters are
also used in this profile. This profile is enabled when non-zero values are assigned to the <tx_threshold> and
<rx_threshold> parameters along with the <monitor_interval> parameter.
• Fast PSP : This profile is a variant of the Traffic Based PSP which exits power save mode even for a single
packet and enters the power save mode if no packet is transferred for the <monitor_interval> amount of
duration. This profile is enabled independently for the Transmit and Receive directions if the <tx_threshold>
and <rx_threshold> parameters are assigned zero, respectively, while assigning a non-zero value to the
<monitor_interval> parameter.
15.3 Wakeup Procedures and Data Retrieval
When in power save mode, the module wakes up at periodic intervals or due to certain events (like pending
transmit packets from the Host). At every wake up, the module has to poll the Access Point and check whether
there are any pending Rx packets destined for the module. The module uses different protocols to retrieve data
from the Access Point based on the protocol supported by the Access Point. These data retrieval methods
(protocol-based) are used to further classify the power save profiles described in the previous section into Max PSP,
Periodic UAPSD and Transmit based UAPSD.
The MAX PSP and UAPSD modes are explained below:
Out of two ULP Handshake Modes (GPIO (signal) based or Message (packet) based), GPIO based mode is
more effective. If target platform does not have free/spare GPIO, they can use message based mode.
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