On Sat, Jan 25, 2014 at 08:15:46AM +0000, Antti P Miettinen wrote:

From: Lorenzo Pieralisi <redacted>
Subject: [PATCH RFC v2 2/2] Documentation: arm: define DT C-states bindings
Date: Mon, 20 Jan 2014 17:47:59 +0000

quoted

+	- latency
+		Usage: Required
+		Value type: <prop-encoded-array>
+		Definition: List of u32 values representing worst case latency
+			    in microseconds required to enter and exit the
+			    C-state, one value per OPP [2]. The list should
+			    be specified in the same order as the operating
+			    points property list of the cpu this state is
+			    valid on.
+			    If no OPP bindings are present, the latency value
+			    is associated with the current OPP of CPUs in the
+			    system.

I'm afraid the CPU OPP is not enough to capture the variance in
latencies. Especially memory frequency affects some of the latencies
very stronly.

That's why I defined the worst case. How did you implemented it in your
idle drivers ? That would help generalize it, after all these bindings
are there to simplify drivers upstreaming, feedback welcome.

Thanks,
Lorenzo