lib/tests/igt_edid: introduce EDID sanity checks

The idea is to make sure we don't completely break EDIDs by performing some
basic sanity-checking in lib tests.

The test currently only checks the base and alt EDIDs. More EDIDs will be added
in the future: HDMI audio, 4K, 3D and so on.

The logic is mostly borrowed from lib/tests/igt_hdmi_inject.c. This patch is
part of the "let's unify igt_edid and igt_hdmi_inject" series.

Signed-off-by: Simon Ser <simon.ser@intel.com>
Reviewed-by: Martin Peres <martin.peres@linux.intel.com>

2 files changed, 97 insertions, 0 deletions

diff --git a/lib/tests/igt_edid.c b/lib/tests/igt_edid.c
new file mode 100644
index 00000000..6cf6b5c1
--- /dev/null
+++ b/lib/tests/igt_edid.c
@@ -0,0 +1,96 @@
+/*
+ * Copyright © 2019 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ * Authors: Simon Ser <simon.ser@intel.com>
+ */
+
+#include "config.h"
+
+#include <stdbool.h>
+
+#include "igt_core.h"
+#include "igt_kms.h"
+#include "igt_edid.h"
+
+static const unsigned char edid_header[] = {
+	0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00
+};
+
+/**
+ * Sanity check the header of the base EDID block.
+ */
+static bool edid_header_is_valid(const unsigned char *raw_edid)
+{
+	size_t i;
+
+	for (i = 0; i < sizeof(edid_header); i++)
+		if (raw_edid[i] != edid_header[i])
+			return false;
+
+	return true;
+}
+
+/**
+ * Sanity check the checksum of the EDID block.
+ */
+static bool edid_block_checksum(const unsigned char *raw_edid)
+{
+	size_t i;
+	unsigned char csum = 0;
+
+	for (i = 0; i < EDID_LENGTH; i++) {
+		csum += raw_edid[i];
+	}
+
+	return csum == 0;
+}
+
+typedef const unsigned char *(*get_edid_func)(void);
+
+igt_simple_main
+{
+	const struct {
+		const char *desc;
+		get_edid_func f;
+		size_t exts;
+	} funcs[] = {
+		{ "base", igt_kms_get_base_edid, 0 },
+		{ "alt", igt_kms_get_alt_edid, 0 },
+		{0},
+	}, *f;
+	const unsigned char *edid;
+	size_t i;
+
+	for (f = funcs; f->f; f++) {
+		edid = f->f();
+
+		igt_assert_f(edid_header_is_valid(edid),
+			     "invalid header on %s EDID", f->desc);
+		/* check base edid block */
+		igt_assert_f(edid_block_checksum(edid),
+			     "checksum failed on %s EDID", f->desc);
+		/* check extension blocks, if any */
+		for (i = 0; i < f->exts; i++)
+			igt_assert_f(edid_block_checksum(edid + (i + 1) * EDID_LENGTH),
+				     "CEA block checksum failed on %s EDID", f->desc);
+	}
+}
diff --git a/lib/tests/meson.build b/lib/tests/meson.build
index eb75cbd5..b930ee6e 100644
--- a/lib/tests/meson.build
+++ b/lib/tests/meson.build
@@ -3,6 +3,7 @@ lib_tests = [
 	'igt_can_fail',
 	'igt_can_fail_simple',
 	'igt_conflicting_args',
+	'igt_edid',
 	'igt_exit_handler',
 	'igt_fork',
 	'igt_fork_helper',