prevent recursive display refresh

Author: dhalbert

shared-module/busdisplay/BusDisplay.c

@@ -309,11 +309,14 @@ static bool _refresh_area(busdisplay_busdisplay_obj_t *self, const displayio_are
 }
 
 static void _refresh_display(busdisplay_busdisplay_obj_t *self) {
+    if (!displayio_display_core_start_refresh(&self->core)) {
+        // Refresh for this display already in progress.
+        return;
+    }
     if (!displayio_display_bus_is_free(&self->bus)) {
         // A refresh on this bus is already in progress.  Try next display.
         return;
     }
-    displayio_display_core_start_refresh(&self->core);
     const displayio_area_t *current_area = _get_refresh_areas(self);
     while (current_area != NULL) {
         _refresh_area(self, current_area);

shared-module/epaperdisplay/EPaperDisplay.c

@@ -187,6 +187,11 @@ void epaperdisplay_epaperdisplay_change_refresh_mode_parameters(epaperdisplay_ep
 }
 
 static void epaperdisplay_epaperdisplay_start_refresh(epaperdisplay_epaperdisplay_obj_t *self) {
+    if (!displayio_display_core_start_refresh(&self->core)) {
+        // Refresh on this display already in progress.
+        return;
+    }
+
     if (!displayio_display_bus_is_free(&self->bus)) {
         // Can't acquire display bus; skip updating this display. Try next display.
         return;
@@ -201,7 +206,6 @@ static void epaperdisplay_epaperdisplay_start_refresh(epaperdisplay_epaperdispla
     if (mp_hal_is_interrupted()) {
         return;
     }
-    displayio_display_core_start_refresh(&self->core);
 }
 
 uint32_t common_hal_epaperdisplay_epaperdisplay_get_time_to_refresh(epaperdisplay_epaperdisplay_obj_t *self) {

shared-module/framebufferio/FramebufferDisplay.c

@@ -217,7 +217,10 @@ static void _refresh_display(framebufferio_framebufferdisplay_obj_t *self) {
     if (!self->bufinfo.buf) {
         return;
     }
-    displayio_display_core_start_refresh(&self->core);
+    if (!displayio_display_core_start_refresh(&self->core)) {
+        // Refresh on this display already in progress.
+        return;
+    }
     const displayio_area_t *current_area = _get_refresh_areas(self);
     if (current_area) {
         bool transposed = (self->core.rotation == 90 || self->core.rotation == 270);