mpm: dt overlay handling: Better error handling, fewer FIXMEs

2 files changed, 33 insertions, 15 deletions

diff --git a/mpm/python/usrp_mpm/dtoverlay.py b/mpm/python/usrp_mpm/dtoverlay.py
index 65b350a04..a16b8a40e 100644
--- a/mpm/python/usrp_mpm/dtoverlay.py
+++ b/mpm/python/usrp_mpm/dtoverlay.py
@@ -42,6 +42,17 @@ def get_overlay_attrs(overlay_name):
             attrs[attr_name] = attr_val
     return attrs
 
+def is_applied(overlay_name):
+    """
+    Returns True if the overlay is already applied, False if not.
+    """
+    try:
+        return open(
+            os.path.join(SYSFS_OVERLAY_BASE_DIR, overlay_name, 'status')
+        ).read().strip() == 'applied'
+    except IOError:
+        return False
+
 def list_overlays(applied_only=False):
     """
     List all registered kernel modules. Returns a dict of dicts:
@@ -74,14 +85,20 @@ def apply_overlay(overlay_name):
     Applies the given overlay. Does not check if the overlay is loaded.
     """
     get_logger("DTO").trace("Applying overlay `{}'...".format(overlay_name))
-    # TODO don't use this script
-    os.system("overlay add {}".format(overlay_name))
+    overlay_path = os.path.join(SYSFS_OVERLAY_BASE_DIR, overlay_name)
+    if not os.path.exists(overlay_path):
+        os.mkdir(overlay_path)
+    open(
+        os.path.join(SYSFS_OVERLAY_BASE_DIR, overlay_name, 'path'), 'w'
+    ).write("{}.dtbo".format(overlay_name))
 
 def apply_overlay_safe(overlay_name):
     """
     Only apply an overlay if it's not yet applied.
+
+    Finally, checks that the overlay was applied and throws an exception if not.
     """
-    if overlay_name in list_overlays(applied_only=True).keys():
+    if is_applied(overlay_name):
         get_logger("DTO").debug(
             "Overlay `{}' was already applied, not applying again.".format(
                 overlay_name
@@ -89,14 +106,15 @@ def apply_overlay_safe(overlay_name):
         )
     else:
         apply_overlay(overlay_name)
+    if not is_applied(overlay_name):
+        raise RuntimeError("Failed to apply overlay `{}'".format(overlay_name))
 
 def rm_overlay(overlay_name):
     """
     Removes the given overlay. Does not check if the overlay is loaded.
     """
     get_logger("DTO").trace("Removing overlay `{}'...".format(overlay_name))
-    # TODO don't use this script
-    os.system("overlay rm {}".format(overlay_name))
+    os.rmdir(os.path.join(SYSFS_OVERLAY_BASE_DIR, overlay_name))
 
 def rm_overlay_safe(overlay_name):
     """
diff --git a/mpm/python/usrp_mpm/periph_manager/base.py b/mpm/python/usrp_mpm/periph_manager/base.py
index a9259f304..143243f7a 100644
--- a/mpm/python/usrp_mpm/periph_manager/base.py
+++ b/mpm/python/usrp_mpm/periph_manager/base.py
@@ -324,6 +324,16 @@ class PeriphManagerBase(object):
                     self.log.warning("No dboard PID found!")
                 else:
                     self.log.debug("Found dboard PID in EEPROM: 0x{:04X}".format(db_pid))
+            db_class = get_dboard_class_from_pid(db_pid)
+            if db_class is None:
+                self.log.warning("Could not identify daughterboard class for PID {:04X}!".format(db_pid))
+                continue
+            self.log.trace("Dboard requires device tree overlays: {}".format(
+                db_class.dt_overlays
+            ))
+            for overlay in db_class.dt_overlays:
+                # FIXME don't hardcode XG
+                dtoverlay.apply_overlay_safe(overlay.format(sfp="XG"))
             if len(self.dboard_spimaster_addrs) > dboard_idx:
                 spi_nodes = sorted(get_spidev_nodes(self.dboard_spimaster_addrs[dboard_idx]))
                 self.log.debug("Found spidev nodes: {0}".format(spi_nodes))
@@ -337,16 +347,6 @@ class PeriphManagerBase(object):
                 'spi_nodes': spi_nodes,
             }
             # This will actually instantiate the dboard class:
-            db_class = get_dboard_class_from_pid(db_pid)
-            if db_class is None:
-                self.log.warning("Could not identify daughterboard class for PID {:04X}!".format(db_pid))
-                continue
-            self.log.trace("Dboard requires device tree overlays: {}".format(
-                db_class.dt_overlays
-            ))
-            for overlay in db_class.dt_overlays:
-                # FIXME don't hardcode XG
-                dtoverlay.apply_overlay_safe(overlay.format(sfp="XG"))
             self.dboards.append(db_class(dboard_idx, **dboard_info))
         self.log.info("Found {} daughterboard(s).".format(len(self.dboards)))