Merge "SF: Add EDID-ID Fabrication Logic" into main

Author: Treehugger Robot

libs/ui/DisplayIdentification.cpp

@@ -26,6 +26,7 @@
 #include <string>
 #include <string_view>
 
+#include <ftl/concat.h>
 #include <ftl/hash.h>
 #include <log/log.h>
 #include <ui/DisplayIdentification.h>
@@ -423,4 +424,27 @@ PhysicalDisplayId getVirtualDisplayId(uint32_t id) {
     return PhysicalDisplayId::fromEdid(0, kVirtualEdidManufacturerId, id);
 }
 
+PhysicalDisplayId generateEdidDisplayId(const Edid& edid) {
+    const ftl::Concat displayDetailsString{edid.manufacturerId,
+                                           edid.productId,
+                                           ftl::truncated<13>(edid.displayName),
+                                           edid.manufactureWeek,
+                                           edid.manufactureOrModelYear,
+                                           edid.physicalSizeInCm.getWidth(),
+                                           edid.physicalSizeInCm.getHeight()};
+
+    // String has to be cropped to 64 characters (at most) for ftl::stable_hash.
+    // This is fine as the accuracy or completeness of the above fields is not
+    // critical for a ID fabrication.
+    const std::optional<uint64_t> hashedDisplayDetailsOpt =
+            ftl::stable_hash(std::string_view(displayDetailsString.c_str(), 64));
+
+    // Combine the hashes via bit-shifted XORs.
+    const uint64_t id = (hashedDisplayDetailsOpt.value_or(0) << 17) ^
+            (edid.hashedBlockZeroSerialNumberOpt.value_or(0) >> 11) ^
+            (edid.hashedDescriptorBlockSerialNumberOpt.value_or(0) << 23);
+
+    return PhysicalDisplayId::fromEdidHash(id);
+}
+
 } // namespace android

libs/ui/include/ui/DisplayId.h

@@ -81,12 +81,17 @@ struct PhysicalDisplayId : DisplayId {
         return PhysicalDisplayId(id);
     }
 
-    // Returns a stable ID based on EDID information.
+    // Returns a stable ID based on EDID and port information.
     static constexpr PhysicalDisplayId fromEdid(uint8_t port, uint16_t manufacturerId,
                                                 uint32_t modelHash) {
         return PhysicalDisplayId(FLAG_STABLE, port, manufacturerId, modelHash);
     }
 
+    // Returns a stable and consistent ID based exclusively on EDID information.
+    static constexpr PhysicalDisplayId fromEdidHash(uint64_t hashedEdid) {
+        return PhysicalDisplayId(hashedEdid);
+    }
+
     // Returns an unstable ID. If EDID is available using "fromEdid" is preferred.
     static constexpr PhysicalDisplayId fromPort(uint8_t port) {
         constexpr uint16_t kManufacturerId = 0;
@@ -103,6 +108,8 @@ struct PhysicalDisplayId : DisplayId {
     // Flag indicating that the ID is stable across reboots.
     static constexpr uint64_t FLAG_STABLE = 1ULL << 62;
 
+    using DisplayId::DisplayId;
+
     constexpr PhysicalDisplayId(uint64_t flags, uint8_t port, uint16_t manufacturerId,
                                 uint32_t modelHash)
           : DisplayId(flags | (static_cast<uint64_t>(manufacturerId) << 40) |

libs/ui/include/ui/DisplayIdentification.h

@@ -74,6 +74,7 @@ struct Edid {
     std::optional<uint64_t> hashedDescriptorBlockSerialNumberOpt;
     PnpId pnpId;
     uint32_t modelHash;
+    // Up to 13 characters of ASCII text terminated by LF and padded with SP.
     std::string_view displayName;
     uint8_t manufactureOrModelYear;
     uint8_t manufactureWeek;
@@ -91,4 +92,8 @@ std::optional<DisplayIdentificationInfo> parseDisplayIdentificationData(
 
 PhysicalDisplayId getVirtualDisplayId(uint32_t id);
 
+// Generates a consistent, stable, and hashed display ID that is based on the
+// display's parsed EDID fields.
+PhysicalDisplayId generateEdidDisplayId(const Edid& edid);
+
 } // namespace android

libs/ui/tests/DisplayIdentification_test.cpp

@@ -376,6 +376,22 @@ TEST(DisplayIdentificationTest, parseDisplayIdentificationData) {
     EXPECT_EQ(4633127902230889474, tertiaryInfo->id.value);
 }
 
+TEST(DisplayIdentificationTest, generateEdidDisplayId) {
+    const auto firstExternalDisplayEdidOpt = parseEdid(getExternalEdid());
+    ASSERT_TRUE(firstExternalDisplayEdidOpt);
+    const PhysicalDisplayId firstExternalDisplayId =
+            generateEdidDisplayId(firstExternalDisplayEdidOpt.value());
+
+    const auto secondExternalDisplayEdidOpt = parseEdid(getExternalEedid());
+    ASSERT_TRUE(secondExternalDisplayEdidOpt);
+    const PhysicalDisplayId secondExternalDisplayId =
+            generateEdidDisplayId(secondExternalDisplayEdidOpt.value());
+
+    // Display IDs should be unique.
+    EXPECT_EQ(4067182673952280501u, firstExternalDisplayId.value);
+    EXPECT_EQ(14712168404707886855u, secondExternalDisplayId.value);
+}
+
 TEST(DisplayIdentificationTest, deviceProductInfo) {
     using ManufactureYear = DeviceProductInfo::ManufactureYear;
     using ManufactureWeekAndYear = DeviceProductInfo::ManufactureWeekAndYear;