2 files changed, 22 insertions, 0 deletions
diff --git a/src/ipa/rpi/controller/controller.cpp b/src/ipa/rpi/controller/controller.cpp
index e62becd8..5ca98b98 100644
--- a/src/ipa/rpi/controller/controller.cpp
+++ b/src/ipa/rpi/controller/controller.cpp
@@ -17,6 +17,7 @@
 
 using namespace RPiController;
 using namespace libcamera;
+using namespace std::literals::chrono_literals;
 
 LOG_DEFINE_CATEGORY(RPiController)
 
@@ -37,6 +38,7 @@ static const std::map<std::string, Controller::HardwareConfig> HardwareConfigMap
 			.numGammaPoints = 33,
 			.pipelineWidth = 13,
 			.statsInline = false,
+			.minPixelProcessingTime = 0s,
 		}
 	},
 	{
@@ -51,6 +53,24 @@ static const std::map<std::string, Controller::HardwareConfig> HardwareConfigMap
 			.numGammaPoints = 64,
 			.pipelineWidth = 16,
 			.statsInline = true,
+
+			/*
+			 * The constraint below is on the rate of pixels going
+			 * from CSI2 peripheral to ISP-FE (400Mpix/s, plus tiny
+			 * overheads per scanline, for which 380Mpix/s is a
+			 * conservative bound).
+			 *
+			 * There is a 64kbit data FIFO before the bottleneck,
+			 * which means that in all reasonable cases the
+			 * constraint applies at a timescale >= 1 scanline, so
+			 * adding horizontal blanking can prevent loss.
+			 *
+			 * If the backlog were to grow beyond 64kbit during a
+			 * single scanline, there could still be loss. This
+			 * could happen using 4 lanes at 1.5Gbps at 10bpp with
+			 * frames wider than ~16,000 pixels.
+			 */
+			.minPixelProcessingTime = 1.0us / 380,
 		}
 	},
 };
diff --git a/src/ipa/rpi/controller/controller.h b/src/ipa/rpi/controller/controller.h
index 6e5f5952..170aea74 100644
--- a/src/ipa/rpi/controller/controller.h
+++ b/src/ipa/rpi/controller/controller.h
@@ -15,6 +15,7 @@
 #include <vector>
 #include <string>
 
+#include <libcamera/base/utils.h>
 #include "libcamera/internal/yaml_parser.h"
 
 #include "camera_mode.h"
@@ -47,6 +48,7 @@ public:
 		unsigned int numGammaPoints;
 		unsigned int pipelineWidth;
 		bool statsInline;
+		libcamera::utils::Duration minPixelProcessingTime;
 	};
 
 	Controller();