ALSA: hwdep - Fix coding style

Fix misc coding style issues in hwdep.h and add some comments.
Signed-off-by: Takashi Iwai <tiwai@suse.de>

include/sound/hwdep.h

@@ -27,18 +27,28 @@
 
 struct snd_hwdep;
 
+/* hwdep file ops; all ops can be NULL */
 struct snd_hwdep_ops {
-	long long (*llseek) (struct snd_hwdep *hw, struct file * file, long long offset, int orig);
-	long (*read) (struct snd_hwdep *hw, char __user *buf, long count, loff_t *offset);
-	long (*write) (struct snd_hwdep *hw, const char __user *buf, long count, loff_t *offset);
-	int (*open) (struct snd_hwdep * hw, struct file * file);
-	int (*release) (struct snd_hwdep *hw, struct file * file);
-	unsigned int (*poll) (struct snd_hwdep *hw, struct file * file, poll_table * wait);
-	int (*ioctl) (struct snd_hwdep *hw, struct file * file, unsigned int cmd, unsigned long arg);
-	int (*ioctl_compat) (struct snd_hwdep *hw, struct file * file, unsigned int cmd, unsigned long arg);
-	int (*mmap) (struct snd_hwdep *hw, struct file * file, struct vm_area_struct * vma);
-	int (*dsp_status) (struct snd_hwdep *hw, struct snd_hwdep_dsp_status *status);
-	int (*dsp_load) (struct snd_hwdep *hw, struct snd_hwdep_dsp_image *image);
+	long long (*llseek)(struct snd_hwdep *hw, struct file *file,
+			    long long offset, int orig);
+	long (*read)(struct snd_hwdep *hw, char __user *buf,
+		     long count, loff_t *offset);
+	long (*write)(struct snd_hwdep *hw, const char __user *buf,
+		      long count, loff_t *offset);
+	int (*open)(struct snd_hwdep *hw, struct file * file);
+	int (*release)(struct snd_hwdep *hw, struct file * file);
+	unsigned int (*poll)(struct snd_hwdep *hw, struct file *file,
+			     poll_table *wait);
+	int (*ioctl)(struct snd_hwdep *hw, struct file *file,
+		     unsigned int cmd, unsigned long arg);
+	int (*ioctl_compat)(struct snd_hwdep *hw, struct file *file,
+			    unsigned int cmd, unsigned long arg);
+	int (*mmap)(struct snd_hwdep *hw, struct file *file,
+		    struct vm_area_struct *vma);
+	int (*dsp_status)(struct snd_hwdep *hw,
+			  struct snd_hwdep_dsp_status *status);
+	int (*dsp_load)(struct snd_hwdep *hw,
+			struct snd_hwdep_dsp_image *image);
 };
 
 struct snd_hwdep {
@@ -61,9 +71,9 @@ struct snd_hwdep {
 	void (*private_free) (struct snd_hwdep *hwdep);
 
 	struct mutex open_mutex;
-	int used;
-	unsigned int dsp_loaded;
-	unsigned int exclusive: 1;
+	int used;			/* reference counter */
+	unsigned int dsp_loaded;	/* bit fields of loaded dsp indices */
+	unsigned int exclusive:1;	/* exclusive access mode */
 };
 
 extern int snd_hwdep_new(struct snd_card *card, char *id, int device,