In "3.3.1 Capturing PSATE" in "IHI0068D_amba_low_power_interface_spec", there is a sentence that says
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PSTATE can be captured when a request is denied.
The device can either retain knowledge of its current state during a P-Channel request or sample the PSTATE value again after a denial when PREQ goes LOW.
Therefore, the PSTATE value can be captured when the device samples PREQ LOW with PDENY HIGH.
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Why does the Device capture the PSTATE in a situation where PREQ LOW with PDENY HIGH?
In my opinion, if the device has already set PDENY to HIGH, it means that the device will not power state transition to that PSTATE.
If so, even if the device captures the PSTATE, it will not power state transition to that PSTATE, and then the device will be useless to capture the PSTATE.
Why does the device capture the PSTATE at PREQ LOW with PDENY HIGH anyway?