Add reset() to display busses to detect whether it works

3 files changed, 15 insertions, 5 deletions

diff --git a/shared-module/displayio/FourWire.c b/shared-module/displayio/FourWire.c
index 64ad80665..7294e9772 100644
--- a/shared-module/displayio/FourWire.c
+++ b/shared-module/displayio/FourWire.c
@@ -55,7 +55,9 @@ void common_hal_displayio_fourwire_construct(displayio_fourwire_obj_t* self,
     common_hal_digitalio_digitalinout_construct(&self->chip_select, chip_select);
     common_hal_digitalio_digitalinout_switch_to_output(&self->chip_select, true, DRIVE_MODE_PUSH_PULL);
 
+    self->reset.base.type = &mp_type_NoneType;
     if (reset != NULL) {
+        self->reset.base.type = &digitalio_digitalinout_type;
         common_hal_digitalio_digitalinout_construct(&self->reset, reset);
         common_hal_digitalio_digitalinout_switch_to_output(&self->reset, true, DRIVE_MODE_PUSH_PULL);
         never_reset_pin_number(reset->number);
@@ -76,12 +78,16 @@ void common_hal_displayio_fourwire_deinit(displayio_fourwire_obj_t* self) {
     reset_pin_number(self->reset.pin->number);
 }
 
-void common_hal_displayio_fourwire_reset(mp_obj_t obj) {
+bool common_hal_displayio_fourwire_reset(mp_obj_t obj) {
     displayio_fourwire_obj_t* self = MP_OBJ_TO_PTR(obj);
+    if (self->reset.base.type == &mp_type_NoneType) {
+        return false;
+    }
     common_hal_digitalio_digitalinout_set_value(&self->reset, false);
     common_hal_time_delay_ms(1);
     common_hal_digitalio_digitalinout_set_value(&self->reset, true);
     common_hal_time_delay_ms(1);
+    return true;
 }
 
 bool common_hal_displayio_fourwire_bus_free(mp_obj_t obj) {
diff --git a/shared-module/displayio/I2CDisplay.c b/shared-module/displayio/I2CDisplay.c
index 23ebc0889..95830ba0e 100644
--- a/shared-module/displayio/I2CDisplay.c
+++ b/shared-module/displayio/I2CDisplay.c
@@ -55,7 +55,9 @@ void common_hal_displayio_i2cdisplay_construct(displayio_i2cdisplay_obj_t* self,
 
     self->address = device_address;
 
+    self->reset.base.type = &mp_type_NoneType;
     if (reset != NULL) {
+        self->reset.base.type = &digitalio_digitalinout_type;
         common_hal_digitalio_digitalinout_construct(&self->reset, reset);
         common_hal_digitalio_digitalinout_switch_to_output(&self->reset, true, DRIVE_MODE_PUSH_PULL);
         never_reset_pin_number(reset->number);
@@ -71,16 +73,18 @@ void common_hal_displayio_i2cdisplay_deinit(displayio_i2cdisplay_obj_t* self) {
     reset_pin_number(self->reset.pin->number);
 }
 
-
-void common_hal_displayio_i2cdisplay_reset(mp_obj_t obj) {
+bool common_hal_displayio_i2cdisplay_reset(mp_obj_t obj) {
     displayio_i2cdisplay_obj_t* self = MP_OBJ_TO_PTR(obj);
+    if (self->reset.base.type == &mp_type_NoneType) {
+        return false;
+    }
 
     common_hal_digitalio_digitalinout_set_value(&self->reset, false);
     common_hal_mcu_delay_us(1);
     common_hal_digitalio_digitalinout_set_value(&self->reset, true);
+    return true;
 }
 
-
 bool common_hal_displayio_i2cdisplay_bus_free(mp_obj_t obj) {
     displayio_i2cdisplay_obj_t* self = MP_OBJ_TO_PTR(obj);
     if (!common_hal_busio_i2c_try_lock(self->bus)) {
diff --git a/shared-module/displayio/display_core.h b/shared-module/displayio/display_core.h
index c837ce913..b1a412883 100644
--- a/shared-module/displayio/display_core.h
+++ b/shared-module/displayio/display_core.h
@@ -33,7 +33,7 @@
 
 #define NO_COMMAND 0x100
 
-typedef void (*display_bus_bus_reset)(mp_obj_t bus);
+typedef bool (*display_bus_bus_reset)(mp_obj_t bus);
 typedef bool (*display_bus_bus_free)(mp_obj_t bus);
 typedef bool (*display_bus_begin_transaction)(mp_obj_t bus);
 typedef void (*display_bus_send)(mp_obj_t bus, bool command, bool toggle_every_byte, uint8_t *data, uint32_t data_length);