[igt-dev] [PATCH i-g-t 1/2] igt_eld: add igt_is_igt

[Simon Ser <simon.ser@intel.com>]

This function parses the monitor name from an ELD blob and checks whether it
comes from an IGT EDID.

Signed-off-by: Simon Ser <simon.ser@intel.com>
---
 lib/igt_eld.c | 23 +++++++++++++++++++++++
 lib/igt_eld.h |  1 +
 2 files changed, 24 insertions(+)

diff --git a/lib/igt_eld.c b/lib/igt_eld.c
index 16c4ac06c6f6..640496b0a160 100644
--- a/lib/igt_eld.c
+++ b/lib/igt_eld.c
@@ -262,3 +262,26 @@ bool eld_has_igt(void)
 	struct eld_entry eld;
 	return eld_get_igt(&eld);
 }
+
+/** eld_is_igt: check whether the ELD blob comes from an IGT EDID */
+bool eld_is_igt(const char *eld, size_t eld_size)
+{
+	char name[17];
+	int name_size;
+
+	igt_assert_f(eld_size >= 20 && eld_size <= 256,
+		     "Invalid ELD size: %zu\n", eld_size);
+
+	name_size = eld[4] & 0x1F;
+	igt_assert_f(name_size <= 16 && 20 + name_size <= eld_size,
+		     "Invalid monitor name size in ELD: %d\n", name_size);
+	if (name_size == 0) {
+		igt_debug("ELD doesn't contain a monitor name\n");
+		return false;
+	}
+
+	memcpy(name, &eld[20], name_size);
+	name[name_size] = '\0';
+	igt_debug("Checking ELD with monitor name: %s\n", name);
+	return strcmp(name, "IGT") == 0;
+}
diff --git a/lib/igt_eld.h b/lib/igt_eld.h
index 7c4489f054f1..36f000abe3f9 100644
--- a/lib/igt_eld.h
+++ b/lib/igt_eld.h
@@ -51,5 +51,6 @@ struct eld_entry {
 
 bool eld_get_igt(struct eld_entry *eld);
 bool eld_has_igt(void);
+bool eld_is_igt(const char *eld, size_t eld_size);
 
 #endif
-- 
2.23.0

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