Revert "Download QNN SDK outside of CMake for wheel builds"

.ci/scripts/wheel/pre_build_script.sh

@@ -44,16 +44,3 @@ fi
 # able to see the installed torch package.
 
 "${GITHUB_WORKSPACE}/${REPOSITORY}/install_requirements.sh" --example
-
-# Download Qualcomm QNN SDK on Linux x86_64 so the wheel build can include the
-# QNN backend.  The SDK is large, so we download it here (outside CMake) rather
-# than during cmake configure.
-if [[ "$(uname -s)" == "Linux" && "$(uname -m)" == "x86_64" ]]; then
-  echo "Downloading Qualcomm QNN SDK..."
-  QNN_SDK_ROOT=$(python3 \
-    "${GITHUB_WORKSPACE}/${REPOSITORY}/backends/qualcomm/scripts/download_qnn_sdk.py" \
-    --print-sdk-path)
-  export QNN_SDK_ROOT
-  echo "QNN_SDK_ROOT=${QNN_SDK_ROOT}" >> "${GITHUB_ENV}"
-  echo "QNN SDK downloaded to ${QNN_SDK_ROOT}"
-fi

.ci/scripts/wheel/test_linux.py

@@ -5,25 +5,10 @@
 # This source code is licensed under the BSD-style license found in the
 # LICENSE file in the root directory of this source tree.
 
-import platform
-
 import test_base
 from examples.models import Backend, Model
 
 if __name__ == "__main__":
-    # On Linux x86_64 the wheel is built with the Qualcomm backend.
-    # Verify that it was registered correctly.
-    if platform.system() == "Linux" and platform.machine() in ("x86_64", "amd64"):
-        from executorch.extension.pybindings.portable_lib import (
-            _get_registered_backend_names,
-        )
-
-        registered = _get_registered_backend_names()
-        assert (
-            "QnnBackend" in registered
-        ), f"QnnBackend not found in registered backends: {registered}"
-        print("✓ QnnBackend is registered")
-
     test_base.run_tests(
         model_tests=[
             test_base.ModelTest(

.github/workflows/pull.yml

@@ -16,6 +16,7 @@ jobs:
   test-qnn-wheel-packages-linux:
     name: test-qnn-wheel-packages-linux
     uses: pytorch/test-infra/.github/workflows/linux_job_v2.yml@main
+    if: false
     permissions:
       id-token: write
       contents: read

backends/qualcomm/CMakeLists.txt

@@ -23,19 +23,9 @@ get_filename_component(
   _common_include_directories "${EXECUTORCH_SOURCE_DIR}/.." ABSOLUTE
 )
 
-# If QNN_SDK_ROOT was not passed as a CMake variable, fall back to the
-# environment variable.  Prefer downloading the SDK *outside* of CMake (e.g. via
-# backends/qualcomm/scripts/download_qnn_sdk.py) and passing the path in.
-if(NOT DEFINED QNN_SDK_ROOT AND DEFINED ENV{QNN_SDK_ROOT})
-  set(QNN_SDK_ROOT
-      $ENV{QNN_SDK_ROOT}
-      CACHE PATH "Qualcomm SDK root directory" FORCE
-  )
-endif()
-
-# Last-resort fallback: download during cmake configure when building wheels and
-# QNN_SDK_ROOT was not provided externally.
-if(NOT DEFINED QNN_SDK_ROOT AND EXECUTORCH_BUILD_WHEEL_DO_NOT_USE)
+# We only download QNN SDK when we build pip wheel for ExecuTorch. Please don't
+# change this code unless you know what you are doing.
+if(EXECUTORCH_BUILD_WHEEL_DO_NOT_USE)
   set(_qnn_default_sdk_dir "${CMAKE_CURRENT_BINARY_DIR}/sdk/qnn")
 
   if(EXISTS "${_qnn_default_sdk_dir}" AND EXISTS "${_qnn_default_sdk_dir}/lib")
@@ -45,7 +35,7 @@ if(NOT DEFINED QNN_SDK_ROOT AND EXECUTORCH_BUILD_WHEEL_DO_NOT_USE)
         CACHE PATH "Qualcomm SDK root directory" FORCE
     )
   else()
-    message(STATUS "Downloading Qualcomm SDK (fallback)")
+    message(STATUS "Downloading Qualcomm SDK")
     execute_process(
       COMMAND
         ${PYTHON_EXECUTABLE}

setup.py

@@ -706,17 +706,6 @@ def run(self):  # noqa C901
         ):
             cmake_configuration_args += ["-DEXECUTORCH_BUILD_CUDA=ON"]
 
-        # Check if QNN SDK is available (via QNN_SDK_ROOT env var), and if so,
-        # enable building the Qualcomm backend by default.
-        qnn_sdk_root = os.environ.get("QNN_SDK_ROOT", "").strip()
-        if qnn_sdk_root and install_utils.is_cmake_option_on(
-            cmake_configuration_args, "EXECUTORCH_BUILD_QNN", default=True
-        ):
-            cmake_configuration_args += [
-                "-DEXECUTORCH_BUILD_QNN=ON",
-                f"-DQNN_SDK_ROOT={qnn_sdk_root}",
-            ]
-
         with Buck2EnvironmentFixer():
             # Generate the cmake cache from scratch to ensure that the cache state
             # is predictable.

tools/cmake/preset/pybind.cmake

@@ -37,7 +37,7 @@ elseif(CMAKE_SYSTEM_NAME STREQUAL "Linux")
   set_overridable_option(EXECUTORCH_BUILD_EXTENSION_LLM_RUNNER ON)
   set_overridable_option(EXECUTORCH_BUILD_EXTENSION_LLM ON)
   if(CMAKE_SYSTEM_PROCESSOR MATCHES "^(x86_64|amd64|i.86)$")
-    set_overridable_option(EXECUTORCH_BUILD_QNN ON)
+    set_overridable_option(EXECUTORCH_BUILD_QNN OFF)
   endif()
 elseif(CMAKE_SYSTEM_NAME STREQUAL "Windows" OR CMAKE_SYSTEM_NAME STREQUAL
                                                "WIN32"