protomatter: more memory allocation fixes

 - bump supervisor alloc count by 4 (we actually use 5)
 - move reconstruct to after gc heap is reset
 - destroy protomatter object entirely if not used by a FramebufferDisplay
 - ensure previous supervisor allocations are released
 - zero out pointers so GC can collect them

3 files changed, 22 insertions, 4 deletions

diff --git a/shared-module/_protomatter/Protomatter.c b/shared-module/_protomatter/Protomatter.c
index cbb60db6d..bec9586f8 100644
--- a/shared-module/_protomatter/Protomatter.c
+++ b/shared-module/_protomatter/Protomatter.c
@@ -78,6 +78,11 @@ void common_hal_protomatter_protomatter_reconstruct(protomatter_protomatter_obj_
         // verify that the matrix is big enough
         mp_get_index(mp_obj_get_type(self->framebuffer), self->bufinfo.len, MP_OBJ_NEW_SMALL_INT(self->bufsize-1), false);
     } else {
+        _PM_FREE(self->bufinfo.buf);
+        _PM_FREE(self->core.rgbPins);
+        _PM_FREE(self->core.addr);
+        _PM_FREE(self->core.screenData);
+
         self->framebuffer = NULL;
         self->bufinfo.buf = _PM_allocator_impl(self->bufsize);
         self->bufinfo.len = self->bufsize;
@@ -156,6 +161,7 @@ void common_hal_protomatter_protomatter_deinit(protomatter_protomatter_obj_t* se
     if (self->core.rgbPins) {
         _PM_free(&self->core);
     }
+    memset(&self->core, 0, sizeof(self->core));
 
     self->base.type = NULL;
 }
diff --git a/shared-module/_protomatter/allocator.h b/shared-module/_protomatter/allocator.h
index 8d9d7ff96..9b7590df3 100644
--- a/shared-module/_protomatter/allocator.h
+++ b/shared-module/_protomatter/allocator.h
@@ -6,7 +6,7 @@
 #include "supervisor/memory.h"
 
 #define _PM_ALLOCATOR _PM_allocator_impl
-#define _PM_FREE _PM_free_impl
+#define _PM_FREE(x) (_PM_free_impl((x)), (x)=NULL, (void)0)
 
 static inline void *_PM_allocator_impl(size_t sz) {
     supervisor_allocation *allocation = allocate_memory(align32_size(sz), true);    
@@ -22,8 +22,6 @@ static inline void _PM_free_impl(void *ptr_in) {
     
     if (allocation) {
         free_memory(allocation);
-    } else {
-        m_free(ptr_in);
     }
 }
 
diff --git a/shared-module/displayio/__init__.c b/shared-module/displayio/__init__.c
index 225aa2008..dfa3e7473 100644
--- a/shared-module/displayio/__init__.c
+++ b/shared-module/displayio/__init__.c
@@ -21,6 +21,18 @@
 
 primary_display_t displays[CIRCUITPY_DISPLAY_LIMIT];
 
+STATIC bool any_display_uses_this_protomatter(protomatter_protomatter_obj_t* pm) {
+    for (uint8_t i = 0; i < CIRCUITPY_DISPLAY_LIMIT; i++) {
+        if (displays[i].framebuffer_display.base.type == &framebufferio_framebufferdisplay_type) {
+            framebufferio_framebufferdisplay_obj_t* display = &displays[i].framebuffer_display;
+            if (display->framebuffer == pm) {
+                return true;
+            }
+        }
+    }
+    return false;
+}
+
 // Check for recursive calls to displayio_background.
 bool displayio_background_in_progress = false;
 
@@ -152,7 +164,9 @@ void reset_displays(void) {
 #if CIRCUITPY_PROTOMATTER
         } else if (displays[i].protomatter.base.type == &protomatter_Protomatter_type) {
             protomatter_protomatter_obj_t * pm = &displays[i].protomatter;
-            common_hal_protomatter_protomatter_reconstruct(pm, NULL);
+            if(!any_display_uses_this_protomatter(pm)) {
+                common_hal_protomatter_protomatter_deinit(pm);
+            }
 #endif
         } else {
             // Not an active display bus.