SF: Parse, hash, and cache block 0 serial number
More EDID fields are required as a part of migrating to EDID-based
display IDs. This CL parses the device's serial number from bytes 12-15
of block 0 in the EDID blob, hashes it using a stable hash, and serves
it as a part of the Edid struct.
Later, amongst others, this value will be used to fabricate a unique
display ID that is based on the display's EDID.
See:
1. EDID spec: https://glenwing.github.io/docs/VESA-EEDID-A2.pdf
2. https://en.wikipedia.org/wiki/Extended_Display_Identification_Data#Structure,_version_1.4
Flag: com.android.graphics.surfaceflinger.flags.stable_edid_ids
Bug: 378923334
Test: DisplayIdentification_test
Change-Id: I8e5c79f2f51c2fd2085dfaba7f5c45fbc698cbcb
diff --git a/libs/ui/DisplayIdentification.cpp b/libs/ui/DisplayIdentification.cpp
index 503f92f..5cdaa71 100644
--- a/libs/ui/DisplayIdentification.cpp
+++ b/libs/ui/DisplayIdentification.cpp
@@ -19,9 +19,12 @@
#include <algorithm>
#include <cctype>
+#include <cstdint>
#include <numeric>
#include <optional>
#include <span>
+#include <string>
+#include <string_view>
#include <ftl/hash.h>
#include <log/log.h>
@@ -194,6 +197,21 @@
const uint16_t productId =
static_cast<uint16_t>(edid[kProductIdOffset] | (edid[kProductIdOffset + 1] << 8));
+ // Bytes 12-15: display serial number, in little-endian (LSB). This field is
+ // optional and its absence is marked by having all bytes set to 0x00.
+ // Values do not represent ASCII characters.
+ constexpr size_t kSerialNumberOffset = 12;
+ if (edid.size() < kSerialNumberOffset + sizeof(uint32_t)) {
+ ALOGE("Invalid EDID: block zero S/N is truncated.");
+ return {};
+ }
+ const uint32_t blockZeroSerialNumber = edid[kSerialNumberOffset] +
+ (edid[kSerialNumberOffset + 1] << 8) + (edid[kSerialNumberOffset + 2] << 16) +
+ (edid[kSerialNumberOffset + 3] << 24);
+ const auto hashedBlockZeroSNOpt = blockZeroSerialNumber == 0
+ ? std::nullopt
+ : ftl::stable_hash(std::string_view(std::to_string(blockZeroSerialNumber)));
+
constexpr size_t kManufactureWeekOffset = 16;
if (edid.size() < kManufactureWeekOffset + sizeof(uint8_t)) {
ALOGE("Invalid EDID: manufacture week is truncated.");
@@ -350,6 +368,7 @@
return Edid{
.manufacturerId = manufacturerId,
.productId = productId,
+ .hashedBlockZeroSerialNumberOpt = hashedBlockZeroSNOpt,
.pnpId = *pnpId,
.modelHash = modelHash,
.displayName = displayName,
diff --git a/libs/ui/include/ui/DisplayIdentification.h b/libs/ui/include/ui/DisplayIdentification.h
index 3f938d6..85e5cee 100644
--- a/libs/ui/include/ui/DisplayIdentification.h
+++ b/libs/ui/include/ui/DisplayIdentification.h
@@ -69,6 +69,7 @@
struct Edid {
uint16_t manufacturerId;
uint16_t productId;
+ std::optional<uint64_t> hashedBlockZeroSerialNumberOpt;
PnpId pnpId;
uint32_t modelHash;
std::string_view displayName;
diff --git a/libs/ui/tests/DisplayIdentification_test.cpp b/libs/ui/tests/DisplayIdentification_test.cpp
index cf0e98b..fbbe719 100644
--- a/libs/ui/tests/DisplayIdentification_test.cpp
+++ b/libs/ui/tests/DisplayIdentification_test.cpp
@@ -33,7 +33,7 @@
namespace {
const unsigned char kInternalEdid[] =
- "\x00\xff\xff\xff\xff\xff\xff\x00\x4c\xa3\x42\x31\x00\x00\x00\x00"
+ "\x00\xff\xff\xff\xff\xff\xff\x00\x4c\xa3\x42\x31\x4e\x61\xbc\x00"
"\x00\x15\x01\x03\x80\x1a\x10\x78\x0a\xd3\xe5\x95\x5c\x60\x90\x27"
"\x19\x50\x54\x00\x00\x00\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01"
"\x01\x01\x01\x01\x01\x01\x9e\x1b\x00\xa0\x50\x20\x12\x30\x10\x30"
@@ -54,7 +54,7 @@
// Extended EDID with timing extension.
const unsigned char kExternalEedid[] =
- "\x00\xff\xff\xff\xff\xff\xff\x00\x4c\x2d\xfe\x08\x00\x00\x00\x00"
+ "\x00\xff\xff\xff\xff\xff\xff\x00\x4c\x2d\xfe\x08\xb1\x7f\x39\x05"
"\x29\x15\x01\x03\x80\x10\x09\x78\x0a\xee\x91\xa3\x54\x4c\x99\x26"
"\x0f\x50\x54\xbd\xef\x80\x71\x4f\x81\xc0\x81\x00\x81\x80\x95\x00"
"\xa9\xc0\xb3\x00\x01\x01\x02\x3a\x80\x18\x71\x38\x2d\x40\x58\x2c"
@@ -112,7 +112,7 @@
"\x07";
const unsigned char kCtlDisplayEdid[] =
- "\x00\xff\xff\xff\xff\xff\xff\x00\x0e\x8c\x9d\x24\x00\x00\x00\x00"
+ "\x00\xff\xff\xff\xff\xff\xff\x00\x0e\x8c\x9d\x24\x30\x41\xab\x00"
"\xff\x17\x01\x04\xa5\x34\x1d\x78\x3a\xa7\x25\xa4\x57\x51\xa0\x26"
"\x10\x50\x54\xbf\xef\x80\xb3\x00\xa9\x40\x95\x00\x81\x40\x81\x80"
"\x95\x0f\x71\x4f\x90\x40\x02\x3a\x80\x18\x71\x38\x2d\x40\x58\x2c"
@@ -191,6 +191,8 @@
EXPECT_EQ(hash("121AT11-801"), 626564263);
EXPECT_TRUE(edid->displayName.empty());
EXPECT_EQ(12610, edid->productId);
+ EXPECT_TRUE(edid->hashedBlockZeroSerialNumberOpt.has_value());
+ EXPECT_EQ(ftl::stable_hash("12345678"), edid->hashedBlockZeroSerialNumberOpt.value());
EXPECT_EQ(21, edid->manufactureOrModelYear);
EXPECT_EQ(0, edid->manufactureWeek);
EXPECT_EQ(26, edid->physicalSizeInCm.width);
@@ -209,6 +211,8 @@
EXPECT_EQ(hash("HP ZR30w"), 918492362);
EXPECT_EQ("HP ZR30w", edid->displayName);
EXPECT_EQ(10348, edid->productId);
+ EXPECT_TRUE(edid->hashedBlockZeroSerialNumberOpt.has_value());
+ EXPECT_EQ(ftl::stable_hash("16843009"), edid->hashedBlockZeroSerialNumberOpt.value());
EXPECT_EQ(22, edid->manufactureOrModelYear);
EXPECT_EQ(2, edid->manufactureWeek);
EXPECT_EQ(64, edid->physicalSizeInCm.width);
@@ -227,6 +231,8 @@
EXPECT_EQ(hash("SAMSUNG"), 1201368132);
EXPECT_EQ("SAMSUNG", edid->displayName);
EXPECT_EQ(2302, edid->productId);
+ EXPECT_TRUE(edid->hashedBlockZeroSerialNumberOpt.has_value());
+ EXPECT_EQ(ftl::stable_hash("87654321"), edid->hashedBlockZeroSerialNumberOpt.value());
EXPECT_EQ(21, edid->manufactureOrModelYear);
EXPECT_EQ(41, edid->manufactureWeek);
EXPECT_EQ(16, edid->physicalSizeInCm.width);
@@ -251,6 +257,8 @@
EXPECT_EQ(hash("Panasonic-TV"), 3876373262);
EXPECT_EQ("Panasonic-TV", edid->displayName);
EXPECT_EQ(41622, edid->productId);
+ EXPECT_TRUE(edid->hashedBlockZeroSerialNumberOpt.has_value());
+ EXPECT_EQ(ftl::stable_hash("16843009"), edid->hashedBlockZeroSerialNumberOpt.value());
EXPECT_EQ(29, edid->manufactureOrModelYear);
EXPECT_EQ(0, edid->manufactureWeek);
EXPECT_EQ(128, edid->physicalSizeInCm.width);
@@ -275,6 +283,7 @@
EXPECT_EQ(hash("Hisense"), 2859844809);
EXPECT_EQ("Hisense", edid->displayName);
EXPECT_EQ(0, edid->productId);
+ EXPECT_FALSE(edid->hashedBlockZeroSerialNumberOpt.has_value());
EXPECT_EQ(29, edid->manufactureOrModelYear);
EXPECT_EQ(18, edid->manufactureWeek);
EXPECT_EQ(0, edid->physicalSizeInCm.width);
@@ -299,6 +308,8 @@
EXPECT_EQ(hash("LP2361"), 1523181158);
EXPECT_EQ("LP2361", edid->displayName);
EXPECT_EQ(9373, edid->productId);
+ EXPECT_TRUE(edid->hashedBlockZeroSerialNumberOpt.has_value());
+ EXPECT_EQ(ftl::stable_hash("11223344"), edid->hashedBlockZeroSerialNumberOpt.value());
EXPECT_EQ(23, edid->manufactureOrModelYear);
EXPECT_EQ(0xff, edid->manufactureWeek);
EXPECT_EQ(52, edid->physicalSizeInCm.width);