};
 
 static int acpi_video_bus_POST_open_fs(struct inode *inode, struct file *file);
-static int acpi_video_bus_write_POST(struct file *file,
+static ssize_t acpi_video_bus_write_POST(struct file *file,
        const char __user *buffer, size_t count, loff_t *data);
 static const struct file_operations acpi_video_bus_POST_fops = {
        .owner = THIS_MODULE,
 };
 
 static int acpi_video_bus_DOS_open_fs(struct inode *inode, struct file *file);
-static int acpi_video_bus_write_DOS(struct file *file,
+static ssize_t acpi_video_bus_write_DOS(struct file *file,
        const char __user *buffer, size_t count, loff_t *data);
 static const struct file_operations acpi_video_bus_DOS_fops = {
        .owner = THIS_MODULE,
 
 static int acpi_video_device_state_open_fs(struct inode *inode,
                                           struct file *file);
-static int acpi_video_device_write_state(struct file *file,
+static ssize_t acpi_video_device_write_state(struct file *file,
        const char __user *buffer, size_t count, loff_t *data);
 static const struct file_operations acpi_video_device_state_fops = {
        .owner = THIS_MODULE,
 
 static int acpi_video_device_brightness_open_fs(struct inode *inode,
                                                struct file *file);
-static int acpi_video_device_write_brightness(struct file *file,
+static ssize_t acpi_video_device_write_brightness(struct file *file,
        const char __user *buffer, size_t count, loff_t *data);
 static struct file_operations acpi_video_device_brightness_fops = {
        .owner = THIS_MODULE,