From 8e9a4944dbbb4a22d149bb989faf32db0a979766 Mon Sep 17 00:00:00 2001
From: Fernando Sahmkow <fsahmkow27@gmail.com>
Date: Mon, 10 Feb 2020 10:32:51 -0400
Subject: [PATCH] GPU: Implement GPU Clock correctly.

---
 src/video_core/engines/maxwell_3d.cpp |  3 ++-
 src/video_core/gpu.cpp                | 14 +++++++++++++-
 src/video_core/gpu.h                  |  2 ++
 3 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/src/video_core/engines/maxwell_3d.cpp b/src/video_core/engines/maxwell_3d.cpp
index 2a58557952..a7e1dee040 100644
--- a/src/video_core/engines/maxwell_3d.cpp
+++ b/src/video_core/engines/maxwell_3d.cpp
@@ -9,6 +9,7 @@
 #include "core/core_timing.h"
 #include "video_core/engines/maxwell_3d.h"
 #include "video_core/engines/shader_type.h"
+#include "video_core/gpu.h"
 #include "video_core/memory_manager.h"
 #include "video_core/rasterizer_interface.h"
 #include "video_core/textures/texture.h"
@@ -533,7 +534,7 @@ void Maxwell3D::StampQueryResult(u64 payload, bool long_query) {
         LongQueryResult query_result{};
         query_result.value = payload;
         // TODO(Subv): Generate a real GPU timestamp and write it here instead of CoreTiming
-        query_result.timestamp = system.CoreTiming().GetTicks();
+        query_result.timestamp = system.GPU().GetTicks();
         memory_manager.WriteBlock(sequence_address, &query_result, sizeof(query_result));
     } else {
         memory_manager.Write<u32>(sequence_address, static_cast<u32>(payload));
diff --git a/src/video_core/gpu.cpp b/src/video_core/gpu.cpp
index 062ca83b81..4aca39faf1 100644
--- a/src/video_core/gpu.cpp
+++ b/src/video_core/gpu.cpp
@@ -6,6 +6,7 @@
 #include "common/microprofile.h"
 #include "core/core.h"
 #include "core/core_timing.h"
+#include "core/core_timing_util.h"
 #include "core/memory.h"
 #include "video_core/engines/fermi_2d.h"
 #include "video_core/engines/kepler_compute.h"
@@ -122,6 +123,17 @@ bool GPU::CancelSyncptInterrupt(const u32 syncpoint_id, const u32 value) {
     return true;
 }
 
+// This values were reversed engineered by fincs from NVN
+// The gpu clock is reported in units of 385/625 nanoseconds
+constexpr u64 gpu_ticks_num = 384;
+constexpr u64 gpu_ticks_den = 625;
+
+u64 GPU::GetTicks() const {
+    const u64 cpu_ticks = system.CoreTiming().GetTicks();
+    const u64 nanoseconds = Core::Timing::CyclesToNs(cpu_ticks).count();
+    return (nanoseconds * gpu_ticks_num) / gpu_ticks_den;
+}
+
 void GPU::FlushCommands() {
     renderer.Rasterizer().FlushCommands();
 }
@@ -340,7 +352,7 @@ void GPU::ProcessSemaphoreTriggerMethod() {
         block.sequence = regs.semaphore_sequence;
         // TODO(Kmather73): Generate a real GPU timestamp and write it here instead of
         // CoreTiming
-        block.timestamp = system.CoreTiming().GetTicks();
+        block.timestamp = GetTicks();
         memory_manager->WriteBlock(regs.semaphore_address.SemaphoreAddress(), &block,
                                    sizeof(block));
     } else {
diff --git a/src/video_core/gpu.h b/src/video_core/gpu.h
index b648317bbe..07727210c1 100644
--- a/src/video_core/gpu.h
+++ b/src/video_core/gpu.h
@@ -192,6 +192,8 @@ public:
 
     bool CancelSyncptInterrupt(u32 syncpoint_id, u32 value);
 
+    u64 GetTicks() const;
+
     std::unique_lock<std::mutex> LockSync() {
         return std::unique_lock{sync_mutex};
     }