Please let us know which NAND flash you are using full part number so that we can refer the datasheet of NAND flash device.Also please provide your code for review.
Thanks for your reply, Krishna.
I suspect that circuit schematic of Nandflash's WP pin maybe be wrong. Can the WP pin be directly connected to control pin of the controller? Or is there a need to connect a pull-up resistor or capacitor?