mtd: spinand: Do not erase the block before writing a bad block marker

Currently when marking a block, we use spinand_erase_op() to erase
the block before writing the marker to the OOB area. Doing so without
waiting for the operation to finish can lead to the marking failing
silently and no bad block marker being written to the flash.

In fact we don't need to do an erase at all before writing the BBM.
The ECC is disabled for raw accesses to the OOB data and we don't
need to work around any issues with chips reporting ECC errors as it
is known to be the case for raw NAND.

Fixes: 7529df465248 ("mtd: nand: Add core infrastructure to support SPI NANDs")
Cc: stable@vger.kernel.org
Signed-off-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20200218100432.32433-4-frieder.schrempf@kontron.de

drivers/mtd/nand/spi/core.c

@@ -712,19 +712,10 @@ static int spinand_markbad(struct nand_device *nand, const struct nand_pos *pos)
 	};
 	int ret;
 
-	/* Erase block before marking it bad. */
 	ret = spinand_select_target(spinand, pos->target);
 	if (ret)
 		return ret;
 
-	ret = spinand_write_enable_op(spinand);
-	if (ret)
-		return ret;
-
-	ret = spinand_erase_op(spinand, pos);
-	if (ret)
-		return ret;
-
 	return spinand_write_page(spinand, &req);
 }