[common] add frame scheduling protocol

client/include/interface/transport.h

@@ -59,6 +59,7 @@ enum
 {
   LG_TRANSPORT_FEATURE_SET_CURSOR_POS = 0x1,
   LG_TRANSPORT_FEATURE_WINDOW_SIZE    = 0x2,
+  LG_TRANSPORT_FEATURE_FRAME_SCHEDULE = 0x4,
 };
 
 typedef uint32_t LG_TransportFeatureFlags;
@@ -133,6 +134,7 @@ typedef struct LG_TransportFrame
 {
   uint64_t serial;
   uint64_t timestamp;
+  uint32_t scheduleGeneration;
   LG_TransportFrameFlags flags;
   // Backend-owned immutable metadata, valid until releaseFrame.
   const LG_TransportFrameFormat * format;
@@ -176,9 +178,20 @@ typedef enum LG_TransportControlType
 {
   LG_TRANSPORT_CONTROL_SET_CURSOR_POS,
   LG_TRANSPORT_CONTROL_WINDOW_SIZE,
+  LG_TRANSPORT_CONTROL_FRAME_SCHEDULE,
 }
 LG_TransportControlType;
 
+enum
+{
+  LG_TRANSPORT_FRAME_SCHEDULE_ACTIVE    = 0x1,
+  LG_TRANSPORT_FRAME_SCHEDULE_RELEASE   = 0x2,
+  LG_TRANSPORT_FRAME_SCHEDULE_RESET     = 0x4,
+  LG_TRANSPORT_FRAME_SCHEDULE_IMMEDIATE = 0x8,
+};
+
+typedef uint32_t LG_TransportFrameScheduleFlags;
+
 typedef struct LG_TransportControl
 {
   LG_TransportControlType type;
@@ -186,6 +199,17 @@ typedef struct LG_TransportControl
   {
     struct { int32_t x, y; } cursorPos;
     struct { uint32_t width, height; } windowSize;
+    struct
+    {
+      uint32_t                       generation;
+      LG_TransportFrameScheduleFlags flags;
+      uint64_t                       period;
+      uint64_t                       targetSlack;
+      int64_t                        phaseError;
+      uint32_t                       feedbackFrameSerial;
+      uint32_t                       lease;
+    }
+    frameSchedule;
   };
 }
 LG_TransportControl;

client/transports/LGMP/lgmp.c

@@ -59,6 +59,7 @@ struct LG_Transport
   bool     connected;
   bool     framePending;
   const KVMFRFrame * pendingFrame;
+  uint32_t clientID;
   uint32_t frameSerial;
   bool     formatValid;
   LG_TransportFrameFormat format;
@@ -297,6 +298,8 @@ static bool lgmp_parseSession(const uint8_t * data, uint32_t size,
     session->features |= LG_TRANSPORT_FEATURE_SET_CURSOR_POS;
   if (header->features & KVMFR_FEATURE_WINDOWSIZE)
     session->features |= LG_TRANSPORT_FEATURE_WINDOW_SIZE;
+  if (header->features & KVMFR_FEATURE_FRAME_SCHEDULE)
+    session->features |= LG_TRANSPORT_FEATURE_FRAME_SCHEDULE;
 
   data += sizeof(*header);
   size -= sizeof(*header);
@@ -359,8 +362,8 @@ static LG_TransportStatus lgmp_connect(LG_Transport * this,
   uint32_t size;
   uint8_t * data;
   uint32_t remoteVersion;
-  LGMP_STATUS status = lgmpClientSessionInit(this->client, &size, &data, NULL,
+  LGMP_STATUS status = lgmpClientSessionInit(this->client, &size, &data,
-      &remoteVersion);
+      &this->clientID, &remoteVersion);
   session->remoteVersion = remoteVersion;
   switch (status)
   {
@@ -390,6 +393,7 @@ static void lgmp_disconnect(LG_Transport * this)
   lgmp_closeQueues(this);
   lgmp_closeDMA(this);
   this->connected = false;
+  this->clientID  = 0;
 }
 
 static bool lgmp_sessionValid(LG_Transport * this)
@@ -538,7 +542,8 @@ static LG_TransportStatus lgmp_nextFrame(LG_Transport * this, bool useDMA,
   this->frameSerial = frame->frameSerial;
 
   memset(result, 0, sizeof(*result));
-  result->serial = frame->frameSerial;
+  result->serial             = frame->frameSerial;
+  result->scheduleGeneration = message.udata;
   if (frame->flags & FRAME_FLAG_BLOCK_SCREENSAVER)
     result->flags |= LG_TRANSPORT_FRAME_BLOCK_SCREENSAVER;
   if (frame->flags & FRAME_FLAG_REQUEST_ACTIVATION)
@@ -763,7 +768,7 @@ static void lgmp_releasePointer(LG_Transport * this,
 static LG_TransportStatus lgmp_sendControl(LG_Transport * this,
     const LG_TransportControl * control, LG_TransportControlToken * token)
 {
-  uint8_t buffer[sizeof(KVMFRWindowSize)];
+  uint8_t buffer[LGMP_MSGS_SIZE];
   uint32_t size;
   switch (control->type)
   {
@@ -789,6 +794,23 @@ static LG_TransportStatus lgmp_sendControl(LG_Transport * this,
       size = sizeof(message);
       break;
     }
+    case LG_TRANSPORT_CONTROL_FRAME_SCHEDULE:
+    {
+      const KVMFRFrameSchedule message = {
+        .msg.type            = KVMFR_MESSAGE_FRAME_SCHEDULE,
+        .clientID            = this->clientID,
+        .generation          = control->frameSchedule.generation,
+        .flags               = control->frameSchedule.flags,
+        .period              = control->frameSchedule.period,
+        .targetSlack         = control->frameSchedule.targetSlack,
+        .phaseError          = control->frameSchedule.phaseError,
+        .feedbackFrameSerial = control->frameSchedule.feedbackFrameSerial,
+        .lease               = control->frameSchedule.lease,
+      };
+      memcpy(buffer, &message, sizeof(message));
+      size = sizeof(message);
+      break;
+    }
     default:
       return LG_TRANSPORT_ERROR;
   }

common/include/common/KVMFR.h

@@ -30,7 +30,7 @@
 #include "LGMPConfig.h"
 
 #define KVMFR_MAGIC   "KVMFR---"
-#define KVMFR_VERSION 25
+#define KVMFR_VERSION 26
 
 // Fallback used by producers that cannot report the source display's SDR
 // white level. IDD frames override this with IDDCX_METADATA2::SdrWhiteLevel.
@@ -59,8 +59,9 @@ typedef uint32_t KVMFRCursorFlags;
 
 enum
 {
-  KVMFR_FEATURE_SETCURSORPOS = 0x1,
+  KVMFR_FEATURE_SETCURSORPOS   = 0x1,
-  KVMFR_FEATURE_WINDOWSIZE   = 0x2
+  KVMFR_FEATURE_WINDOWSIZE     = 0x2,
+  KVMFR_FEATURE_FRAME_SCHEDULE = 0x4
 };
 
 typedef uint32_t KVMFRFeatureFlags;
@@ -68,7 +69,8 @@ typedef uint32_t KVMFRFeatureFlags;
 enum
 {
   KVMFR_MESSAGE_SETCURSORPOS,
-  KVMFR_MESSAGE_WINDOWSIZE
+  KVMFR_MESSAGE_WINDOWSIZE,
+  KVMFR_MESSAGE_FRAME_SCHEDULE
 };
 
 typedef uint32_t KVMFRMessageType;
@@ -268,6 +270,44 @@ typedef struct KVMFRWindowSize
 }
 KVMFRWindowSize;
 
+enum
+{
+  KVMFR_FRAME_SCHEDULE_ACTIVE    = 0x1,
+  KVMFR_FRAME_SCHEDULE_RELEASE   = 0x2,
+  KVMFR_FRAME_SCHEDULE_RESET     = 0x4,
+  KVMFR_FRAME_SCHEDULE_IMMEDIATE = 0x8
+};
+
+typedef uint32_t KVMFRFrameScheduleFlags;
+
+/*
+ * Client presentation scheduling is expressed entirely as durations. Client
+ * and producer monotonic clocks have unrelated epochs and must never be
+ * compared directly.
+ */
+typedef struct KVMFRFrameSchedule
+{
+  KVMFRMessage            msg;
+  uint32_t                clientID;
+  uint32_t                generation;
+  KVMFRFrameScheduleFlags flags;
+  uint64_t                period;
+  uint64_t                targetSlack;
+  int64_t                 phaseError;
+  uint32_t                feedbackFrameSerial;
+  uint32_t                lease;
+  uint8_t                 reserved[16];
+}
+KVMFRFrameSchedule;
+
+#if defined(__cplusplus)
+static_assert(sizeof(KVMFRFrameSchedule) == 64,
+    "KVMFR frame schedule must fit in one LGMP control message");
+#elif defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201112L
+_Static_assert(sizeof(KVMFRFrameSchedule) == 64,
+    "KVMFR frame schedule must fit in one LGMP control message");
+#endif
+
 #ifdef _MSC_VER
 #pragma warning(pop)
 #endif