Revert "Use a single libusb context"

This reverts commit c8a6dc6c23.

libusb on Windows isn't really safe to use from different threads
with a single context.

Source/Core/Common/CMakeLists.txt

@@ -40,11 +40,6 @@ set(SRCS
   Logging/LogManager.cpp
 )
 
-if(LIBUSB_FOUND)
-  set(LIBS ${LIBS} ${LIBUSB_LIBRARIES})
-  set(SRCS ${SRCS} LibusbContext.cpp)
-endif(LIBUSB_FOUND)
-
 if(ANDROID)
   set(SRCS ${SRCS}
     Logging/ConsoleListenerDroid.cpp)

Source/Core/Common/Common.vcxproj

@@ -118,7 +118,6 @@
     <ClInclude Include="Hash.h" />
     <ClInclude Include="IniFile.h" />
     <ClInclude Include="JitRegister.h" />
-    <ClInclude Include="LibusbContext.h" />
     <ClInclude Include="LinearDiskCache.h" />
     <ClInclude Include="MathUtil.h" />
     <ClInclude Include="MD5.h" />
@@ -170,9 +169,6 @@
     <ClCompile Include="Hash.cpp" />
     <ClCompile Include="IniFile.cpp" />
     <ClCompile Include="JitRegister.cpp" />
-    <ClCompile Include="LibusbContext.cpp">
-      <DisableSpecificWarnings>4200;%(DisableSpecificWarnings)</DisableSpecificWarnings>
-    </ClCompile>
     <ClCompile Include="Logging\ConsoleListenerWin.cpp" />
     <ClCompile Include="MathUtil.cpp" />
     <ClCompile Include="MD5.cpp" />

Source/Core/Common/Common.vcxproj.filters

@@ -49,7 +49,6 @@
     <ClInclude Include="FPURoundMode.h" />
     <ClInclude Include="Hash.h" />
     <ClInclude Include="IniFile.h" />
-    <ClInclude Include="LibusbContext.h" />
     <ClInclude Include="LinearDiskCache.h" />
     <ClInclude Include="MathUtil.h" />
     <ClInclude Include="MemArena.h" />
@@ -251,7 +250,6 @@
     <ClCompile Include="FileUtil.cpp" />
     <ClCompile Include="Hash.cpp" />
     <ClCompile Include="IniFile.cpp" />
-    <ClCompile Include="LibusbContext.cpp" />
     <ClCompile Include="MathUtil.cpp" />
     <ClCompile Include="MemArena.cpp" />
     <ClCompile Include="MemoryUtil.cpp" />

Source/Core/Common/LibusbContext.cpp

@@ -1,49 +0,0 @@
-// Copyright 2017 Dolphin Emulator Project
-// Licensed under GPLv2+
-// Refer to the license.txt file included.
-
-#include <libusb.h>
-#include <memory>
-#include <mutex>
-
-#include "Common/LibusbContext.h"
-#include "Common/MsgHandler.h"
-#include "Common/StringUtil.h"
-
-namespace LibusbContext
-{
-static std::shared_ptr<libusb_context> s_libusb_context;
-static std::once_flag s_context_initialized;
-
-static libusb_context* Create()
-{
-  libusb_context* context;
-  const int ret = libusb_init(&context);
-  if (ret < LIBUSB_SUCCESS)
-  {
-    bool is_windows = false;
-#ifdef _WIN32
-    is_windows = true;
-#endif
-    const std::string reason =
-        is_windows && ret == LIBUSB_ERROR_NOT_FOUND ?
-            GetStringT("Failed to initialize libusb because usbdk is not installed.") :
-            StringFromFormat(GetStringT("Failed to initialize libusb (%s).").c_str(),
-                             libusb_error_name(ret));
-    PanicAlertT("%s\nSome USB features will not work.", reason.c_str());
-    return nullptr;
-  }
-  return context;
-}
-
-std::shared_ptr<libusb_context> Get()
-{
-  std::call_once(s_context_initialized, []() {
-    s_libusb_context.reset(Create(), [](auto* context) {
-      if (context != nullptr)
-        libusb_exit(context);
-    });
-  });
-  return s_libusb_context;
-}
-}

Source/Core/Common/LibusbContext.h

@@ -1,15 +0,0 @@
-// Copyright 2017 Dolphin Emulator Project
-// Licensed under GPLv2+
-// Refer to the license.txt file included.
-
-#include <memory>
-
-struct libusb_context;
-
-namespace LibusbContext
-{
-// libusb on Windows is limited to only a single context. Trying to open more
-// than one can cause issues with device enumerations.
-// libusb is thread-safe so this context can be safely used from different threads.
-std::shared_ptr<libusb_context> Get();
-}