app: CMakeLists: auto-include ptl LL userspace overlay for Linux builds

When building ptl for Linux (i.e. os_linux_overlay.conf is in
EXTRA_CONF_FILE), automatically append ll_userspace_overlay.conf so
callers do not need to pass it explicitly. A double-inclusion guard
is included for the case where the caller already lists it.

This keeps os_linux_overlay.conf target-agnostic while ensuring all
ptl Linux builds get the LL userspace configuration.

Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>

Author: kv2019i

app/CMakeLists.txt

@@ -2,6 +2,19 @@
 
 cmake_minimum_required(VERSION 3.21.0)
 
+# Board specific overlays (these must be before find_package(Zephyr))
+# -------------------------------------------------------------------
+
+# Intel PTL: if "os_linux_overlay" used, also add "ll_userspace_overlay"
+if(DEFINED EXTRA_CONF_FILE AND (BOARD MATCHES "/ptl" OR BOARD_QUALIFIERS MATCHES "/ptl"))
+  string(FIND "${EXTRA_CONF_FILE}" "os_linux_overlay" _linux_overlay_idx)
+  string(FIND "${EXTRA_CONF_FILE}" "ll_userspace_overlay" _ll_overlay_idx)
+  if(_linux_overlay_idx GREATER_EQUAL 0 AND _ll_overlay_idx LESS 0)
+    list(APPEND EXTRA_CONF_FILE
+      "${CMAKE_CURRENT_SOURCE_DIR}/overlays/ptl/ll_userspace_overlay.conf")
+  endif()
+endif()
+
 find_package(Zephyr HINTS $ENV{ZEPHYR_BASE})
 project(sample_sof)
 

app/overlays/ptl/ll_userspace_overlay.conf

@@ -1,7 +1,8 @@
 # This is overlay configuration file to enable user-space LL audio
-# pipeline support. This overlay is intended for development
-# purposes. If user-space LL is enabled for some build target by
-# default, the settings should be made in the SOF board file directly.
+# pipeline support.
+#
+# NOTE: this overlay is automatically included if PTL is built
+#       with generic "os_linux_overlay.conf"
 
 # Enable user-space LL support in SOF
 # -----------------------------------