ipa: simple: agc: Make sure activeState.agc expo/again are always initialized

If the first frame of a stream is bad, the IPA will not get called with
frame == 0, leaving activeState.agc expo/again uninitialized. This causes
the agc algorithm to set a very low gain and exposure on the next run
(where it will hit the if (!stats->valid) {} path) resulting in starting
with a black image.

Fix this by using a valid flag instead of checking for frame == 0.

The entire activeState gets cleared to 0 on configure() resetting the new
valid flag.

Signed-off-by: Hans de Goede <johannes.goede@oss.qualcomm.com>
Reviewed-by: Milan Zamazal <mzamazal@redhat.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

src/ipa/simple/algorithms/agc.cpp

@@ -100,7 +100,7 @@ void Agc::updateExposure(IPAContext &context, IPAFrameContext &frameContext, dou
 }
 
 void Agc::process(IPAContext &context,
-		  const uint32_t frame,
+		  [[maybe_unused]] const uint32_t frame,
 		  IPAFrameContext &frameContext,
 		  const SwIspStats *stats,
 		  ControlList &metadata)
@@ -110,13 +110,14 @@ void Agc::process(IPAContext &context,
 	metadata.set(controls::ExposureTime, exposureTime.get<std::micro>());
 	metadata.set(controls::AnalogueGain, frameContext.sensor.gain);
 
-	if (frame == 0) {
+	if (!context.activeState.agc.valid) {
 		/*
 		 * Init active-state from sensor values in case updateExposure()
 		 * does not run for the first frame.
 		 */
 		context.activeState.agc.exposure = frameContext.sensor.exposure;
 		context.activeState.agc.again = frameContext.sensor.gain;
+		context.activeState.agc.valid = true;
 	}
 
 	if (!stats->valid) {

src/ipa/simple/ipa_context.h

@@ -40,6 +40,7 @@ struct IPAActiveState {
 	struct {
 		int32_t exposure;
 		double again;
+		bool valid;
 	} agc;
 
 	struct {