ALSA: compress: Fix kernel doc warnings

Each kernel doc comment expects the definition of the return value and
the summary for each struct / enum in a proper format.  This patch
adds or fixes the missing entries for compress-offload API.

Link: https://lore.kernel.org/r/20220713104759.4365-5-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>

include/uapi/sound/compress_offload.h

@@ -123,7 +123,7 @@ struct snd_compr_codec_caps {
 } __attribute__((packed, aligned(4)));
 
 /**
- * enum sndrv_compress_encoder
+ * enum sndrv_compress_encoder - encoder metadata key
  * @SNDRV_COMPRESS_ENCODER_PADDING: no of samples appended by the encoder at the
  * end of the track
  * @SNDRV_COMPRESS_ENCODER_DELAY: no of samples inserted by the encoder at the

include/uapi/sound/compress_params.h

@@ -250,7 +250,7 @@ struct snd_enc_wma {
 
 
 /**
- * struct snd_enc_vorbis
+ * struct snd_enc_vorbis - Vorbis encoder parameters
  * @quality: Sets encoding quality to n, between -1 (low) and 10 (high).
  * In the default mode of operation, the quality level is 3.
  * Normal quality range is 0 - 10.
@@ -279,7 +279,7 @@ struct snd_enc_vorbis {
 
 
 /**
- * struct snd_enc_real
+ * struct snd_enc_real - RealAudio encoder parameters
  * @quant_bits: number of coupling quantization bits in the stream
  * @start_region: coupling start region in the stream
  * @num_regions: number of regions value
@@ -294,7 +294,7 @@ struct snd_enc_real {
 } __attribute__((packed, aligned(4)));
 
 /**
- * struct snd_enc_flac
+ * struct snd_enc_flac - FLAC encoder parameters
  * @num: serial number, valid only for OGG formats
  *	needs to be set by application
  * @gain: Add replay gain tags

sound/core/compress_offload.c

@@ -818,6 +818,8 @@ static void error_delayed_work(struct work_struct *work)
  * Stop the stream and set its state.
  *
  * Should be called with compressed device lock held.
+ *
+ * Return: zero if successful, or a negative error code
  */
 int snd_compr_stop_error(struct snd_compr_stream *stream,
 			 snd_pcm_state_t state)
@@ -1164,6 +1166,8 @@ static int snd_compress_dev_free(struct snd_device *device)
  * @dirn: device direction, should be of type enum snd_compr_direction
  * @id: ID string
  * @compr: compress device pointer
+ *
+ * Return: zero if successful, or a negative error code
  */
 int snd_compress_new(struct snd_card *card, int device,
 			int dirn, const char *id, struct snd_compr *compr)