mtd: st_spi_fsm: Update Macronix 'QE' configuration

Update the configuration of the Macronix 'QE' bit, such that
we only set or clear the bit if required.
Signed-off-by: Angus Clark <angus.clark@st.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

drivers/mtd/devices/st_spi_fsm.c

@@ -1164,12 +1164,27 @@ static int stfsm_mx25_config(struct stfsm *fsm)
 					      CFG_ERASESEC_TOGGLE_32BIT_ADDR);
 	}
 
-	/* For QUAD mode, set 'QE' STATUS bit */
+	/* Check status of 'QE' bit */
+	stfsm_read_status(fsm, FLASH_CMD_RDSR, &sta);
 	data_pads = ((fsm->stfsm_seq_read.seq_cfg >> 16) & 0x3) + 1;
 	if (data_pads == 4) {
-		stfsm_read_status(fsm, FLASH_CMD_RDSR, &sta);
-		sta |= MX25_STATUS_QE;
-		stfsm_write_status(fsm, sta, 1);
+		if (!(sta & MX25_STATUS_QE)) {
+			/* Set 'QE' */
+			sta |= MX25_STATUS_QE;
+
+			stfsm_write_status(fsm, sta, 1);
+
+			stfsm_wait_busy(fsm);
+		}
+	} else {
+		if (sta & MX25_STATUS_QE) {
+			/* Clear 'QE' */
+			sta &= ~MX25_STATUS_QE;
+
+			stfsm_write_status(fsm, sta, 1);
+
+			stfsm_wait_busy(fsm);
+		}
 	}
 
 	return 0;