ipa: rpi: AF speed up CDAF->PDAF transition. TO BE SQUASHED

Fix phase sign test; allow more extrapolation (clipped) in CAF

Signed-off-by: Nick Hollinghurst <nick.hollinghurst@raspberrypi.com>

Author: njhollinghurst

src/ipa/rpi/controller/rpi/af.cpp

@@ -485,11 +485,12 @@ bool Af::earlyTerminationByPhase(double phase)
 		 * Interpolate/extrapolate the lens position for zero phase.
 		 * Check that the extrapolation is well-conditioned.
 		 */
-		if ((ftarget_ - oldFocus) * (phase - oldPhase) > 0.0) {
+		if ((ftarget_ - oldFocus) * (phase - oldPhase) * cfg_.speeds[speed_].pdafGain < 0.0) {
 			double param = phase / (phase - oldPhase);
-			if (-2.5 <= param && param <= 3.0) {
-				ftarget_ += param * (oldFocus - ftarget_);
+			if ((-2.5 <= param || mode_ == AfModeContinuous) && param <= 3.0) {
 				LOG(RPiAf, Debug) << "ETBP: param=" << param;
+				param = std::max(param, -2.5);
+				ftarget_ += param * (oldFocus - ftarget_);
 				return true;
 			}
 		}