fw_printenv throw atmel spi error

Hello Friend,

We are use atmel at91sam9260ek base linux board, in which we use DataFlash:AT45DB642. Our uboot, environment variable as well as kernel are place here while root file system place in NAND flash and work fine.

Now problem is that whenever we use fw_printenv command to read environment variable from linux terminal it give following error.

# fw_printenv
atmel_spi atmel_spi.0: overrun (4031/4032 remaining)
Read error on /dev/mtd3: Input/output error
# fw_printenv
atmel_spi atmel_spi.0: overrun (4034/4034 remaining)
Read error on /dev/mtd3: Input/output error
# fw_printenv
atmel_spi atmel_spi.0: overrun (4026/4026 remaining)
Read error on /dev/mtd3: Input/output error
# fw_printenv
atmel_spi atmel_spi.0: overrun (4029/4030 remaining)
Read error on /dev/mtd3: Input/output error

Our fw_env.config file is as below..

# cat /etc/fw_env.config

# Configuration file for fw_(printenv/setenv) utility.
# Up to two entries are valid, in this case the redundant
# environment sector is assumed present.
# MTD SPI-dataflash example
# MTD device name       Device offset   Env. size       Flash sector size       Number of sectors
/dev/mtd3               0x4200          0x4200

please help to resolve issue...

Regards,
Ghanshyam