mtd: spi-nor: Check bus width while setting QE bit

spi_nor_write_16bit_sr_and_check() should also check if bus width is
4 before setting QE bit.

Fixes: 39d1e33 ("mtd: spi-nor: Fix clearing of QE bit on lock()/unlock()")
Suggested-by: Michael Walle <michael@walle.cc>
Suggested-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>
Reviewed-by: Michael Walle <michael@walle.cc>
Link: https://lore.kernel.org/r/20230818064524.1229100-2-hsinyi@chromium.org
Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>

Author: hsinyi527

drivers/mtd/spi-nor/core.c

@@ -870,21 +870,22 @@ static int spi_nor_write_16bit_sr_and_check(struct spi_nor *nor, u8 sr1)
 		ret = spi_nor_read_cr(nor, &sr_cr[1]);
 		if (ret)
 			return ret;
-	} else if (nor->params->quad_enable) {
+	} else if (spi_nor_get_protocol_width(nor->read_proto) == 4 &&
+		   spi_nor_get_protocol_width(nor->write_proto) == 4 &&
+		   nor->params->quad_enable) {
 		/*
 		 * If the Status Register 2 Read command (35h) is not
 		 * supported, we should at least be sure we don't
 		 * change the value of the SR2 Quad Enable bit.
 		 *
-		 * We can safely assume that when the Quad Enable method is
-		 * set, the value of the QE bit is one, as a consequence of the
-		 * nor->params->quad_enable() call.
+		 * When the Quad Enable method is set and the buswidth is 4, we
+		 * can safely assume that the value of the QE bit is one, as a
+		 * consequence of the nor->params->quad_enable() call.
 		 *
-		 * We can safely assume that the Quad Enable bit is present in
-		 * the Status Register 2 at BIT(1). According to the JESD216
-		 * revB standard, BFPT DWORDS[15], bits 22:20, the 16-bit
-		 * Write Status (01h) command is available just for the cases
-		 * in which the QE bit is described in SR2 at BIT(1).
+		 * According to the JESD216 revB standard, BFPT DWORDS[15],
+		 * bits 22:20, the 16-bit Write Status (01h) command is
+		 * available just for the cases in which the QE bit is
+		 * described in SR2 at BIT(1).
 		 */
 		sr_cr[1] = SR2_QUAD_EN_BIT1;
 	} else {