2.2.2 LPD-P operating in sequencer mode

If the SEQUENCER parameter is set to one, then the LPD-P operates in sequencer mode.

In sequencer mode, when the LPD-P receives a request on the control P-Channel, it then sequentially sends requests to each of the device P-Channels. The LPD-P waits for the response from each device before sending a request to the next device. The LPD-P waits for all devices to respond before generating the response to the controller.

The value of the unmapped power mode (ctrl_pstate_i[3:0]), controls the sequence order that the LPD-P uses as a priority. If the P-Channel controller issues a request modifying only the operating mode (ctrl_pstate_i[7:4]), then the sequence order is from dev<N−1> to dev<0> if the unmapped operating mode value changes to a lower value, otherwise the sequence order is from dev<0> to dev<N−1>. Also, if DEV_P_CH_<X>_SAME_EN == 0 for any device, then determination of auto accept is based on both the mapped operating mode (dev<X>_pstate_o[7:4]) and mapped power mode (dev<X>_pstate_o[3:0]) values for that device.

Lower power mode entry sequence

When the controller asserts ctrl_preq_i and issues a request to a lower power mode, indicated by a lower value on ctrl_pstate_i[3:0] than previously, regardless of the operating mode ctrl_pstate_i[7:4], the LPD-P sends the request on the highest device P-Channel, dev<DEV_P_CH_NUM−1>_preq_o. If the device accepts the request, then the LPD-P decrements the device number and sends the request to the next device.

If any device denies the request by asserting dev<X>_pdeny_i, then the LPD-P asserts the ctrl_pdeny_o output. The LPD-P does not send a request to the remaining P-Channels. The LPD-P returns the device P-Channels to the previous state in ascending numerical order, from the last device to accept the request to device [DEV_P_CH_NUM−1].

Higher power mode entry sequence

When the controller asserts ctrl_preq_i and issues a request to a higher power mode by setting a higher value on ctrl_pstate_i[3:0], regardless of the operating mode ctrl_pstate_i[7:4], then the LPD-P sends the request on the lowest device P-Channel, dev<0>. If the device accepts the request, then the LPD-P increments the device number and then sends the request to the next device.

If any device denies the request by asserting dev<X>_pdeny_i, then the LPD-P asserts the ctrl_pdeny_o output. The LPD-P does not send a request to the remaining P-Channels. The LPD-P returns the device P-Channels to the previous state in descending numerical order, from the last device to accept the request to device [0].

Same power mode, lower operating mode entry sequence

When the controller asserts ctrl_preq_i and issues a request to the same power mode, indicated by the same value on ctrl_pstate_i[3:0], then the operating mode ctrl_pstate_i[7:4] controls the sequence order. If the operating mode change is to a lower value, the LPD-P sends the request on the highest device P-Channel, dev<DEV_P_CH_NUM−1>_preq_o. If the device accepts the request, then the LPD-P decrements the device number and sends the request to the next device.

If any device denies the request by asserting dev<X>_pdeny_i, then the LPD-P asserts the ctrl_pdeny_o output. The LPD-P does not send a request to the remaining P-Channels. The LPD-P returns the device P-Channels to the previous state in ascending numerical order, from the last device to accept the request to device [DEV_P_CH_NUM−1].

Same power mode, same or higher operating mode entry sequence

When the controller asserts ctrl_preq_i and issues a request to the same power mode, indicated by the same value on ctrl_pstate_i[3:0], then the operating mode ctrl_pstate_i[7:4] controls the sequence order. If the operating mode change is to the same or higher value, the LPD-P sends the request on the lowest device P-Channel, dev<0>. If the device accepts the request, then the LPD-P increments the device number and then sends the request to the next device.

If any device denies the request by asserting dev<X>_pdeny_i, then the LPD-P asserts the ctrl_pdeny_o output. The LPD-P does not send a request to the remaining P-Channels. The LPD-P returns the device P-Channels to the previous state in descending numerical order, from the last device to accept the request to device [0].

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