tests: drivers: video: sw_stats: add tests for VIDEO_SW_DRIVER

Test it by filling a buffer manually with test data and verify that the
statistics produced are matching.

Signed-off-by: Josuah Demangeon <me@josuah.net>

Author: josuah

tests/drivers/video/sw_stats/CMakeLists.txt

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+# SPDX-License-Identifier: Apache-2.0
+
+cmake_minimum_required(VERSION 3.20.0)
+find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
+project(drivers_video_sw_stats)
+
+target_sources(app PRIVATE src/main.c)

tests/drivers/video/sw_stats/prj.conf

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+CONFIG_LOG=y
+CONFIG_VIDEO_LOG_LEVEL_DBG=y
+CONFIG_ZTEST=y
+CONFIG_VIDEO=y
+CONFIG_VIDEO_SW_STATS=y
+CONFIG_VIDEO_BUFFER_POOL_SZ_MAX=16384
+CONFIG_VIDEO_BUFFER_POOL_NUM_MAX=1

tests/drivers/video/sw_stats/src/main.c

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+/*
+ * Copyright (c) 2025 tinyVision.ai Inc.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr/ztest.h>
+#include <zephyr/drivers/video.h>
+#include <zephyr/drivers/video-controls.h>
+#include <zephyr/pixel/print.h>
+
+#define WIDTH 640
+#define HEIGHT 480
+
+uint8_t rggb8frame[WIDTH * HEIGHT * 1];
+uint16_t rgb24hist[(1 << 4) * 3];
+
+ZTEST(video_sw_stats, test_video_sw_stats)
+{
+	const struct device *dev = device_get_binding("VIDEO_SW_STATS");
+	struct video_buffer *vbufp;
+	struct video_stats_channels chan = {
+		.base.flags = VIDEO_STATS_CHANNELS_RGB
+	};
+	struct video_stats_histogram hist = {
+		.base.flags = VIDEO_STATS_HISTOGRAM_RGB,
+		.buckets = rgb24hist,
+		.num_buckets = ARRAY_SIZE(rgb24hist),
+	};
+	struct video_buffer vbuf = {
+		.buffer = rggb8frame,
+		.size = sizeof(rggb8frame),
+		.bytesused = sizeof(rggb8frame),
+	};
+	struct video_format fmt = {
+		.pixelformat = VIDEO_PIX_FMT_RGGB8,
+		.width = WIDTH,
+		.pitch = WIDTH * video_bits_per_pixel(VIDEO_PIX_FMT_RGGB8) / BITS_PER_BYTE,
+		.height = HEIGHT,
+	};
+
+	zexpect_not_null(dev);
+	zexpect_true(device_is_ready(dev));
+
+	/* Load test data on the buffer: upper half completely white */
+
+	memset(rggb8frame, 0xff, sizeof(rggb8frame) / 2);
+
+	zexpect_ok(video_set_format(dev, VIDEO_EP_IN, &fmt));
+
+	/* Test loading a buffer into the device */
+
+	zexpect_ok(video_enqueue(dev, VIDEO_EP_IN, &vbuf));
+
+	/* Test collecting image statistics out of this buffer */
+
+	zexpect_ok(video_get_stats(dev, VIDEO_EP_IN, &chan.base));
+	zexpect_ok(video_get_stats(dev, VIDEO_EP_IN, &hist.base));
+
+	/* Test collecting image statistics out of this buffer */
+
+	zexpect_ok(video_dequeue(dev, VIDEO_EP_IN, &vbufp, K_NO_WAIT));
+	zexpect_not_null(vbufp);
+
+	/* Check the statistics content of channel averages */
+
+	zexpect_equal(chan.base.flags & VIDEO_STATS_CHANNELS_RGB, VIDEO_STATS_CHANNELS_RGB);
+	zexpect_within(chan.rgb[0], 0xff / 2, 10, "%u is average", chan.rgb[0]);
+	zexpect_within(chan.rgb[1], 0xff / 2, 10, "%u is average", chan.rgb[1]);
+	zexpect_within(chan.rgb[2], 0xff / 2, 10, "%u is average", chan.rgb[2]);
+
+	/* Check the channel averagres */
+
+	zexpect_equal(hist.base.flags & VIDEO_STATS_HISTOGRAM_RGB, VIDEO_STATS_HISTOGRAM_RGB);
+	zexpect_not_equal(hist.num_buckets, 0, "The histogram size must not be zero.");
+	zexpect_not_equal(hist.num_values, 0, "The histogram must not be empty.");
+
+	/* Check the histograms */
+
+	zexpect_within(hist.buckets[0], hist.num_values / 2, 10,
+		       "Half of the image is filled with 0x00");
+
+	zexpect_within(hist.buckets[hist.num_buckets - 1], hist.num_values / 2, 10,
+		       "Half of the image is filled with 0xff");
+
+	for (size_t i = hist.num_buckets * 0 / 3 + 1; i < hist.num_buckets * 1 / 3 - 1; i++) {
+		zexpect_equal(hist.buckets[i], 0, "%u: Only 0x00 or 0xff for the red channel", i);
+	}
+
+	for (size_t i = hist.num_buckets * 1 / 3 + 1; i < hist.num_buckets * 2 / 3 - 1; i++) {
+		zexpect_equal(hist.buckets[i], 0, "%u: Only 0x00 or 0xff in the green channel", i);
+	}
+
+	for (size_t i = hist.num_buckets * 2 / 3 + 1; i < hist.num_buckets * 3 / 3 - 1; i++) {
+		zexpect_equal(hist.buckets[i], 0, "%u: Only 0x00 or 0xff in the blue channel", i);
+	}
+}
+
+ZTEST_SUITE(video_sw_stats, NULL, NULL, NULL, NULL, NULL);

tests/drivers/video/sw_stats/testcase.yaml

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+# Copyright (c) 2025 tinyVision.ai Inc.
+# SPDX-License-Identifier: Apache-2.0
+
+tests:
+  drivers.video.sw_stats:
+    tags:
+      - drivers
+      - video
+    platform_allow: native_sim