drm/selftests: Add drm_rect selftests

Add selftests for drm_rect. A few basic ones for clipped and unclipped
cases, and a few special ones for specific bugs we had in the code.

I'm too lazy to think of more corner cases to check at this time.
Maybe later.

Signed-off-by: Ville Syrjälä <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]
Reviewed-by: Daniel Vetter <[e-mail]>
Reviewed-by: Benjamin Gaignard <[e-mail]>

drivers/gpu/drm/selftests/Makefile

···
 # SPDX-License-Identifier: GPL-2.0-only
 test-drm_modeset-y := test-drm_modeset_common.o test-drm_plane_helper.o \
                       test-drm_format.o test-drm_framebuffer.o \
-		      test-drm_damage_helper.o test-drm_dp_mst_helper.o
+		      test-drm_damage_helper.o test-drm_dp_mst_helper.o \
+		      test-drm_rect.o
 
 obj-$(CONFIG_DRM_DEBUG_SELFTEST) += test-drm_mm.o test-drm_modeset.o test-drm_cmdline_parser.o

drivers/gpu/drm/selftests/drm_modeset_selftests.h

···
  *
  * Tests are executed in order by igt/drm_selftests_helper
  */
+selftest(drm_rect_clip_scaled_div_by_zero, igt_drm_rect_clip_scaled_div_by_zero)
+selftest(drm_rect_clip_scaled_not_clipped, igt_drm_rect_clip_scaled_not_clipped)
+selftest(drm_rect_clip_scaled_clipped, igt_drm_rect_clip_scaled_clipped)
+selftest(drm_rect_clip_scaled_signed_vs_unsigned, igt_drm_rect_clip_scaled_signed_vs_unsigned)
 selftest(check_plane_state, igt_check_plane_state)
 selftest(check_drm_format_block_width, igt_check_drm_format_block_width)
 selftest(check_drm_format_block_height, igt_check_drm_format_block_height)

drivers/gpu/drm/selftests/test-drm_modeset_common.h

···
 #ifndef __TEST_DRM_MODESET_COMMON_H__
 #define __TEST_DRM_MODESET_COMMON_H__
 
+#include <linux/errno.h>
+#include <linux/printk.h>
+
 #define FAIL(test, msg, ...) \
 	do { \
 		if (test) { \
···
 
 #define FAIL_ON(x) FAIL((x), "%s", "FAIL_ON(" __stringify(x) ")\n")
 
+int igt_drm_rect_clip_scaled_div_by_zero(void *ignored);
+int igt_drm_rect_clip_scaled_not_clipped(void *ignored);
+int igt_drm_rect_clip_scaled_clipped(void *ignored);
+int igt_drm_rect_clip_scaled_signed_vs_unsigned(void *ignored);
 int igt_check_plane_state(void *ignored);
 int igt_check_drm_format_block_width(void *ignored);
 int igt_check_drm_format_block_height(void *ignored);

drivers/gpu/drm/selftests/test-drm_rect.c

···
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Test cases for the drm_rect functions
+ */
+
+#define pr_fmt(fmt) "drm_rect: " fmt
+
+#include <linux/limits.h>
+
+#include <drm/drm_rect.h>
+
+#include "test-drm_modeset_common.h"
+
+int igt_drm_rect_clip_scaled_div_by_zero(void *ignored)
+{
+	struct drm_rect src, dst, clip;
+	bool visible;
+
+	/*
+	 * Make sure we don't divide by zero when dst
+	 * width/height is zero and dst and clip do not intersect.
+	 */
+	drm_rect_init(&src, 0, 0, 0, 0);
+	drm_rect_init(&dst, 0, 0, 0, 0);
+	drm_rect_init(&clip, 1, 1, 1, 1);
+	visible = drm_rect_clip_scaled(&src, &dst, &clip);
+	FAIL(visible, "Destination not be visible\n");
+	FAIL(drm_rect_visible(&src), "Source should not be visible\n");
+
+	drm_rect_init(&src, 0, 0, 0, 0);
+	drm_rect_init(&dst, 3, 3, 0, 0);
+	drm_rect_init(&clip, 1, 1, 1, 1);
+	visible = drm_rect_clip_scaled(&src, &dst, &clip);
+	FAIL(visible, "Destination not be visible\n");
+	FAIL(drm_rect_visible(&src), "Source should not be visible\n");
+
+	return 0;
+}
+
+int igt_drm_rect_clip_scaled_not_clipped(void *ignored)
+{
+	struct drm_rect src, dst, clip;
+	bool visible;
+
+	/* 1:1 scaling */
+	drm_rect_init(&src, 0, 0, 1 << 16, 1 << 16);
+	drm_rect_init(&dst, 0, 0, 1, 1);
+	drm_rect_init(&clip, 0, 0, 1, 1);
+
+	visible = drm_rect_clip_scaled(&src, &dst, &clip);
+
+	FAIL(src.x1 != 0 || src.x2 != 1 << 16 ||
+	     src.y1 != 0 || src.y2 != 1 << 16,
+	     "Source badly clipped\n");
+	FAIL(dst.x1 != 0 || dst.x2 != 1 ||
+	     dst.y1 != 0 || dst.y2 != 1,
+	     "Destination badly clipped\n");
+	FAIL(!visible, "Destination should be visible\n");
+	FAIL(!drm_rect_visible(&src), "Source should be visible\n");
+
+	/* 2:1 scaling */
+	drm_rect_init(&src, 0, 0, 2 << 16, 2 << 16);
+	drm_rect_init(&dst, 0, 0, 1, 1);
+	drm_rect_init(&clip, 0, 0, 1, 1);
+
+	visible = drm_rect_clip_scaled(&src, &dst, &clip);
+
+	FAIL(src.x1 != 0 || src.x2 != 2 << 16 ||
+	     src.y1 != 0 || src.y2 != 2 << 16,
+	     "Source badly clipped\n");
+	FAIL(dst.x1 != 0 || dst.x2 != 1 ||
+	     dst.y1 != 0 || dst.y2 != 1,
+	     "Destination badly clipped\n");
+	FAIL(!visible, "Destination should be visible\n");
+	FAIL(!drm_rect_visible(&src), "Source should be visible\n");
+
+	/* 1:2 scaling */
+	drm_rect_init(&src, 0, 0, 1 << 16, 1 << 16);
+	drm_rect_init(&dst, 0, 0, 2, 2);
+	drm_rect_init(&clip, 0, 0, 2, 2);
+
+	visible = drm_rect_clip_scaled(&src, &dst, &clip);
+
+	FAIL(src.x1 != 0 || src.x2 != 1 << 16 ||
+	     src.y1 != 0 || src.y2 != 1 << 16,
+	     "Source badly clipped\n");
+	FAIL(dst.x1 != 0 || dst.x2 != 2 ||
+	     dst.y1 != 0 || dst.y2 != 2,
+	     "Destination badly clipped\n");
+	FAIL(!visible, "Destination should be visible\n");
+	FAIL(!drm_rect_visible(&src), "Source should be visible\n");
+
+	return 0;
+}
+
+int igt_drm_rect_clip_scaled_clipped(void *ignored)
+{
+	struct drm_rect src, dst, clip;
+	bool visible;
+
+	/* 1:1 scaling top/left clip */
+	drm_rect_init(&src, 0, 0, 2 << 16, 2 << 16);
+	drm_rect_init(&dst, 0, 0, 2, 2);
+	drm_rect_init(&clip, 0, 0, 1, 1);
+
+	visible = drm_rect_clip_scaled(&src, &dst, &clip);
+
+	FAIL(src.x1 != 0 || src.x2 != 1 << 16 ||
+	     src.y1 != 0 || src.y2 != 1 << 16,
+	     "Source badly clipped\n");
+	FAIL(dst.x1 != 0 || dst.x2 != 1 ||
+	     dst.y1 != 0 || dst.y2 != 1,
+	     "Destination badly clipped\n");
+	FAIL(!visible, "Destination should be visible\n");
+	FAIL(!drm_rect_visible(&src), "Source should be visible\n");
+
+	/* 1:1 scaling bottom/right clip */
+	drm_rect_init(&src, 0, 0, 2 << 16, 2 << 16);
+	drm_rect_init(&dst, 0, 0, 2, 2);
+	drm_rect_init(&clip, 1, 1, 1, 1);
+
+	visible = drm_rect_clip_scaled(&src, &dst, &clip);
+
+	FAIL(src.x1 != 1 << 16 || src.x2 != 2 << 16 ||
+	     src.y1 != 1 << 16 || src.y2 != 2 << 16,
+	     "Source badly clipped\n");
+	FAIL(dst.x1 != 1 || dst.x2 != 2 ||
+	     dst.y1 != 1 || dst.y2 != 2,
+	     "Destination badly clipped\n");
+	FAIL(!visible, "Destination should be visible\n");
+	FAIL(!drm_rect_visible(&src), "Source should be visible\n");
+
+	/* 2:1 scaling top/left clip */
+	drm_rect_init(&src, 0, 0, 4 << 16, 4 << 16);
+	drm_rect_init(&dst, 0, 0, 2, 2);
+	drm_rect_init(&clip, 0, 0, 1, 1);
+
+	visible = drm_rect_clip_scaled(&src, &dst, &clip);
+
+	FAIL(src.x1 != 0 || src.x2 != 2 << 16 ||
+	     src.y1 != 0 || src.y2 != 2 << 16,
+	     "Source badly clipped\n");
+	FAIL(dst.x1 != 0 || dst.x2 != 1 ||
+	     dst.y1 != 0 || dst.y2 != 1,
+	     "Destination badly clipped\n");
+	FAIL(!visible, "Destination should be visible\n");
+	FAIL(!drm_rect_visible(&src), "Source should be visible\n");
+
+	/* 2:1 scaling bottom/right clip */
+	drm_rect_init(&src, 0, 0, 4 << 16, 4 << 16);
+	drm_rect_init(&dst, 0, 0, 2, 2);
+	drm_rect_init(&clip, 1, 1, 1, 1);
+
+	visible = drm_rect_clip_scaled(&src, &dst, &clip);
+
+	FAIL(src.x1 != 2 << 16 || src.x2 != 4 << 16 ||
+	     src.y1 != 2 << 16 || src.y2 != 4 << 16,
+	     "Source badly clipped\n");
+	FAIL(dst.x1 != 1 || dst.x2 != 2 ||
+	     dst.y1 != 1 || dst.y2 != 2,
+	     "Destination badly clipped\n");
+	FAIL(!visible, "Destination should be visible\n");
+	FAIL(!drm_rect_visible(&src), "Source should be visible\n");
+
+	/* 1:2 scaling top/left clip */
+	drm_rect_init(&src, 0, 0, 2 << 16, 2 << 16);
+	drm_rect_init(&dst, 0, 0, 4, 4);
+	drm_rect_init(&clip, 0, 0, 2, 2);
+
+	visible = drm_rect_clip_scaled(&src, &dst, &clip);
+
+	FAIL(src.x1 != 0 || src.x2 != 1 << 16 ||
+	     src.y1 != 0 || src.y2 != 1 << 16,
+	     "Source badly clipped\n");
+	FAIL(dst.x1 != 0 || dst.x2 != 2 ||
+	     dst.y1 != 0 || dst.y2 != 2,
+	     "Destination badly clipped\n");
+	FAIL(!visible, "Destination should be visible\n");
+	FAIL(!drm_rect_visible(&src), "Source should be visible\n");
+
+	/* 1:2 scaling bottom/right clip */
+	drm_rect_init(&src, 0, 0, 2 << 16, 2 << 16);
+	drm_rect_init(&dst, 0, 0, 4, 4);
+	drm_rect_init(&clip, 2, 2, 2, 2);
+
+	visible = drm_rect_clip_scaled(&src, &dst, &clip);
+
+	FAIL(src.x1 != 1 << 16 || src.x2 != 2 << 16 ||
+	     src.y1 != 1 << 16 || src.y2 != 2 << 16,
+	     "Source badly clipped\n");
+	FAIL(dst.x1 != 2 || dst.x2 != 4 ||
+	     dst.y1 != 2 || dst.y2 != 4,
+	     "Destination badly clipped\n");
+	FAIL(!visible, "Destination should be visible\n");
+	FAIL(!drm_rect_visible(&src), "Source should be visible\n");
+
+	return 0;
+}
+
+int igt_drm_rect_clip_scaled_signed_vs_unsigned(void *ignored)
+{
+	struct drm_rect src, dst, clip;
+	bool visible;
+
+	/*
+	 * 'clip.x2 - dst.x1 >= dst width' could result a negative
+	 * src rectangle width which is no longer expected by the
+	 * code as it's using unsigned types. This could lead to
+	 * the clipped source rectangle appering visible when it
+	 * should have been fully clipped. Make sure both rectangles
+	 * end up invisible.
+	 */
+	drm_rect_init(&src, 0, 0, INT_MAX, INT_MAX);
+	drm_rect_init(&dst, 0, 0, 2, 2);
+	drm_rect_init(&clip, 3, 3, 1, 1);
+
+	visible = drm_rect_clip_scaled(&src, &dst, &clip);
+
+	FAIL(visible, "Destination should not be visible\n");
+	FAIL(drm_rect_visible(&src), "Source should not be visible\n");
+
+	return 0;
+}

include/drm/drm_rect.h

···
 #ifndef DRM_RECT_H
 #define DRM_RECT_H
 
+#include <linux/types.h>
+
 /**
  * DOC: rect utils
  *