[RFC PATCH 1/1] drm/format-helper: Add KUnit tests for drm_fb_xrgb8888_to_rgb332()

[José Expósito <jose.exposito89@xxxxxxxxx>]

Test the conversion from XRGB8888 to RGB332.

What is tested?

 - Different values for the X in XRGB8888 to make sure it is ignored
 - Different clip values: Single pixel and full and partial buffer
 - Well know colors: White, black, red, green, blue, magenta, yellow
   and cyan
 - Other colors: Randomly picked
 - Destination pitch

Suggested-by: Javier Martinez Canillas <javierm@xxxxxxxxxx>
Signed-off-by: José Expósito <jose.exposito89@xxxxxxxxx>
---
 drivers/gpu/drm/Kconfig                  |  12 ++
 drivers/gpu/drm/Makefile                 |   3 +
 drivers/gpu/drm/drm_format_helper_test.c | 166 +++++++++++++++++++++++
 3 files changed, 181 insertions(+)
 create mode 100644 drivers/gpu/drm/drm_format_helper_test.c

diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index e88c497fa010..d92be6faef15 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -76,6 +76,18 @@ config DRM_KMS_HELPER
 	help
 	  CRTC helpers for KMS drivers.
 
+config DRM_FORMAR_HELPER_TEST
+	bool "drm_format_helper tests" if !KUNIT_ALL_TESTS
+	depends on DRM && KUNIT=y
+	select DRM_KMS_HELPER
+	default KUNIT_ALL_TESTS
+	help
+	  KUnit tests for the drm_format_helper APIs. This option is not
+	  useful for distributions or general kernels, but only for kernel
+	  developers working on DRM and associated drivers.
+
+	  If in doubt, say "N".
+
 config DRM_DEBUG_DP_MST_TOPOLOGY_REFS
         bool "Enable refcount backtrace history in the DP MST helpers"
 	depends on STACKTRACE_SUPPORT
diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
index 15fe3163f822..6a7d7655d38c 100644
--- a/drivers/gpu/drm/Makefile
+++ b/drivers/gpu/drm/Makefile
@@ -76,6 +76,9 @@ obj-$(CONFIG_DRM_KMS_HELPER) += drm_kms_helper.o
 #
 
 obj-$(CONFIG_DRM_DEBUG_SELFTEST) += selftests/
+obj-$(CONFIG_DRM_FORMAR_HELPER_TEST) += drm_kms_helper.o \
+		drm_format_helper_test.o
+CFLAGS_drm_format_helper_test.o += $(DISABLE_STRUCTLEAK_PLUGIN)
 
 obj-$(CONFIG_DRM_MIPI_DBI) += drm_mipi_dbi.o
 obj-$(CONFIG_DRM_MIPI_DSI) += drm_mipi_dsi.o
diff --git a/drivers/gpu/drm/drm_format_helper_test.c b/drivers/gpu/drm/drm_format_helper_test.c
new file mode 100644
index 000000000000..9c8a3007346c
--- /dev/null
+++ b/drivers/gpu/drm/drm_format_helper_test.c
@@ -0,0 +1,166 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+#include <kunit/test.h>
+
+#include <drm/drm_device.h>
+#include <drm/drm_file.h>
+#include <drm/drm_format_helper.h>
+#include <drm/drm_fourcc.h>
+#include <drm/drm_framebuffer.h>
+#include <drm/drm_gem_framebuffer_helper.h>
+#include <drm/drm_mode.h>
+#include <drm/drm_print.h>
+#include <drm/drm_rect.h>
+
+#include "drm_crtc_internal.h"
+
+#define TEST_BUF_SIZE 50
+#define CLIP(x, y, w, h) { (x), (y), (x) + (w), (y) + (h) }
+
+struct xrgb8888_to_rgb332_case {
+	const char *name;
+	unsigned int pitch;
+	unsigned int dst_pitch;
+	struct drm_rect clip;
+	const u32 xrgb8888[TEST_BUF_SIZE];
+	const u8 expected[4 * TEST_BUF_SIZE];
+};
+
+static struct xrgb8888_to_rgb332_case xrgb8888_to_rgb332_cases[] = {
+	{
+		.name = "Single pixel source",
+		.pitch = 1 * 4,
+		.dst_pitch = 0,
+		.clip = CLIP(0, 0, 1, 1),
+		.xrgb8888 = { 0x01FF0000 },
+		.expected = { 0xE0 },
+	},
+	{
+		.name = "Single pixel clip",
+		.pitch = 2 * 4,
+		.dst_pitch = 0,
+		.clip = CLIP(1, 1, 1, 1),
+		.xrgb8888 = {
+			0x00000000, 0x00000000,
+			0x00000000, 0x10FF0000,
+		},
+		.expected = { 0xE0 },
+	},
+	{
+		.name = "White, black, red, green, blue, magenta, yellow, cyan",
+		.pitch = 4 * 4,
+		.dst_pitch = 0,
+		.clip = CLIP(1, 1, 2, 4),
+		.xrgb8888 = {
+			0x00000000, 0x00000000, 0x00000000, 0x00000000,
+			0x00000000, 0x11FFFFFF, 0x22000000, 0x00000000,
+			0x00000000, 0x33FF0000, 0x4400FF00, 0x00000000,
+			0x00000000, 0x550000FF, 0x66FF00FF, 0x00000000,
+			0x00000000, 0x77FFFF00, 0x8800FFFF, 0x00000000,
+		},
+		.expected = {
+			0xFF, 0x00,
+			0xE0, 0x1C,
+			0x03, 0xE3,
+			0xFC, 0x1F,
+		},
+	},
+	{
+		.name = "Destination pitch",
+		.pitch = 3 * 4,
+		.dst_pitch = 5,
+		.clip = CLIP(0, 0, 3, 3),
+		.xrgb8888 = {
+			0xA10E449C, 0xB1114D05, 0xC1A80303,
+			0xD16C7073, 0xA20E449C, 0xB2114D05,
+			0xC2A80303, 0xD26C7073, 0xA30E449C,
+		},
+		.expected = {
+			0x0A, 0x08, 0xA0, 0x00, 0x00,
+			0x6D, 0x0A, 0x08, 0x00, 0x00,
+			0xA0, 0x6D, 0x0A, 0x00, 0x00,
+		},
+	},
+};
+
+/**
+ * conversion_buf_size - Return the destination buffer size required to convert
+ * between formats.
+ * @src_format: source buffer pixel format (DRM_FORMAT_*)
+ * @dst_format: destination buffer pixel format (DRM_FORMAT_*)
+ * @dst_pitch: Number of bytes between two consecutive scanlines within dst
+ * @clip: Clip rectangle area to convert
+ *
+ * Returns:
+ * The size of the destination buffer or negative value on error.
+ */
+static size_t conversion_buf_size(u32 src_format, u32 dst_format,
+				  unsigned int dst_pitch,
+				  const struct drm_rect *clip)
+{
+	const struct drm_format_info *src_fi = drm_format_info(src_format);
+	const struct drm_format_info *dst_fi = drm_format_info(dst_format);
+	size_t width = drm_rect_width(clip);
+	size_t src_nbytes;
+
+	if (!src_fi || !dst_fi)
+		return -EINVAL;
+
+	if (dst_pitch)
+		width = dst_pitch;
+
+	src_nbytes = width * drm_rect_height(clip) * src_fi->cpp[0];
+	if (!src_nbytes)
+		return 0;
+
+	return (src_nbytes * dst_fi->cpp[0]) / src_fi->cpp[0];
+}
+
+static void xrgb8888_to_rgb332_case_desc(struct xrgb8888_to_rgb332_case *t,
+					 char *desc)
+{
+	strscpy(desc, t->name, KUNIT_PARAM_DESC_SIZE);
+}
+
+KUNIT_ARRAY_PARAM(xrgb8888_to_rgb332, xrgb8888_to_rgb332_cases,
+		  xrgb8888_to_rgb332_case_desc);
+
+static void xrgb8888_to_rgb332_test(struct kunit *test)
+{
+	const struct xrgb8888_to_rgb332_case *params = test->param_value;
+	size_t dst_size;
+	__u8 *dst = NULL;
+
+	struct drm_framebuffer fb = {
+		.format = drm_format_info(DRM_FORMAT_XRGB8888),
+		.pitches = { params->pitch, 0, 0 },
+	};
+
+	dst_size = conversion_buf_size(DRM_FORMAT_XRGB8888, DRM_FORMAT_RGB332,
+				       params->dst_pitch, &params->clip);
+	KUNIT_ASSERT_GT(test, dst_size, 0);
+
+	dst = kzalloc(dst_size, GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, dst);
+
+	drm_fb_xrgb8888_to_rgb332(dst, params->dst_pitch, params->xrgb8888,
+				  &fb, &params->clip);
+	KUNIT_EXPECT_EQ(test, memcmp(dst, params->expected, dst_size), 0);
+}
+
+static struct kunit_case drm_format_helper_test_cases[] = {
+	KUNIT_CASE_PARAM(xrgb8888_to_rgb332_test,
+			 xrgb8888_to_rgb332_gen_params),
+	{}
+};
+
+static struct kunit_suite drm_format_helper_test_suite = {
+	.name = "drm-format-helper-test",
+	.test_cases = drm_format_helper_test_cases,
+};
+
+kunit_test_suite(drm_format_helper_test_suite);
+
+MODULE_DESCRIPTION("KUnit tests for the drm_format_helper APIs");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("José Expósito <jose.exposito89@xxxxxxxxx>");
-- 
2.25.1