Warning: initialization from incompatible pointer type Analysis

In the character driver, this line of code reports a warning:

Warning: initialization from incompatible pointer type

Static ssize_t s3c2440_key_read (struct file * filp, char _ User * Buf, ssize_t count, loff_t * PPOs );

The reason for the analysis is that the function declaration is inconsistent with the function prototype.

Ssize_t count

Change

Size_t count

You can.

Similarly,

Static void s3c2440_key_release (struct inode * inode, struct file * filp );

Replace

Void

Change

Int

You can.

Function prototype and file_operations Member Analysis reference http://blog.sina.com.cn/s/blog_56332e1d0100crc8.html