Permission denied to change max size of the device using sysfs attribute max_size

[harishcpu]

harish@harish-vm:~/ldd/custom_drivers/006_pcd_sysfs$ cd /sys/class/pcd_class/pcdev-0/
harish@harish-vm:/sys/class/pcd_class/pcdev-0$ cat serial_number
PCDEVABC111
harish@harish-vm:/sys/class/pcd_class/pcdev-0$ cat max_size
512
harish@harish-vm:/sys/class/pcd_class/pcdev-0$ echo 100 > max_size
bash: max_size: Permission denied
harish@harish-vm:/sys/class/pcd_class/pcdev-0$ sudo echo 100 > max_size
bash: max_size: Permission denied
harish@harish-vm:/sys/class/pcd_class/pcdev-0$ cat max_size
512