Two tweaks to mclk

Author: tannewt

ports/mimxrt10xx/common-hal/audiobusio/I2SOut.c

@@ -131,10 +131,12 @@ void common_hal_audiobusio_i2sout_deinit(audiobusio_i2sout_obj_t *self) {
     common_hal_reset_pin(self->data);
     self->data = NULL;
 
-    IOMUXC_GPR->GPR1 &= ~(IOMUXC_GPR_GPR1_SAI1_MCLK_DIR_MASK << (self->instance - 1));
+    if (self->mclk != NULL) {
+        IOMUXC_GPR->GPR1 &= ~(IOMUXC_GPR_GPR1_SAI1_MCLK_DIR_MASK << (self->instance - 1));
 
-    common_hal_reset_pin(self->mclk);
-    self->mclk = NULL;
+        common_hal_reset_pin(self->mclk);
+        self->mclk = NULL;
+    }
 }
 
 void common_hal_audiobusio_i2sout_play(audiobusio_i2sout_obj_t *self,

shared-bindings/audiobusio/I2SOut.c

@@ -44,7 +44,7 @@
 //|         word_select: microcontroller.Pin,
 //|         data: microcontroller.Pin,
 //|         *,
-//|         main_clock: microcontroller.Pin = None,
+//|         main_clock: Optional[microcontroller.Pin] = None,
 //|         left_justified: bool = False
 //|     ) -> None:
 //|         """Create a I2SOut object associated with the given pins.