ports/rp2: Make split-heap optional.

My tests found issues when PSRAM is combined with the existing
RAM in a split-heap configuration. Since this option is not
enabled by default on RP2 I have changed it to be optional.

PSRAM will be used exclusively if MICROPY_GC_SPLIT_HEAP == 0,
it will be added to RAM if MICROPY_GC_SPLIT_HEAP == 1,
and the system will fall back to RAM only if it's not detected.

Signed-off-by: Phil Howard <[email protected]>

Author: Gadgetoid

ports/rp2/main.c

@@ -122,12 +122,20 @@ int main(int argc, char **argv) {
     // Initialise stack extents and GC heap.
     mp_cstack_init_with_top(&__StackTop, &__StackTop - &__StackBottom);
 
-    gc_init(&__GcHeapStart, &__GcHeapEnd);
     #if defined(MICROPY_HW_PSRAM_CS_PIN) && MICROPY_HW_ENABLE_PSRAM
     size_t psram_size = psram_init(MICROPY_HW_PSRAM_CS_PIN);
     if (psram_size) {
+        #if MICROPY_GC_SPLIT_HEAP
+        gc_init(&__GcHeapStart, &__GcHeapEnd);
         gc_add((void *)PSRAM_LOCATION, (void *)(PSRAM_LOCATION + psram_size));
+        #else
+        gc_init((void *)PSRAM_LOCATION, (void *)(PSRAM_LOCATION + psram_size));
+        #endif
+    } else {
+        gc_init(&__GcHeapStart, &__GcHeapEnd);
     }
+    #else
+    gc_init(&__GcHeapStart, &__GcHeapEnd);
     #endif
 
     #if MICROPY_PY_LWIP

ports/rp2/mpconfigport.h

@@ -73,8 +73,8 @@
 
 // Memory allocation policies
 #define MICROPY_GC_STACK_ENTRY_TYPE             uint16_t
-#ifdef MICROPY_HW_ENABLE_PSRAM
-#define MICROPY_GC_SPLIT_HEAP                   (1)
+#ifndef MICROPY_GC_SPLIT_HEAP
+#define MICROPY_GC_SPLIT_HEAP                   (0) // whether PSRAM is added to or replaces the heap
 #endif
 #define MICROPY_ALLOC_PATH_MAX                  (128)
 #define MICROPY_QSTR_BYTES_IN_HASH              (1)