ALSA: Constify the snd_pcm_substream struct ops field

The ops field of the snd_pcm_substream struct is never modified inside the ALSA
core. Making it const allows drivers to declare their snd_pcm_ops struct as
const.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

2 files changed, 5 insertions, 3 deletions

diff --git a/include/sound/pcm.h b/include/sound/pcm.h
index b48792fe386b..84b10f9a2832 100644
--- a/include/sound/pcm.h
+++ b/include/sound/pcm.h
@@ -384,7 +384,7 @@ struct snd_pcm_substream {
         unsigned int dma_buf_id;
         size_t dma_max;
         /* -- hardware operations -- */
-        struct snd_pcm_ops *ops;
+        const struct snd_pcm_ops *ops;
         /* -- runtime information -- */
         struct snd_pcm_runtime *runtime;
         /* -- timer section -- */
@@ -871,7 +871,8 @@ const unsigned char *snd_pcm_format_silence_64(snd_pcm_format_t format);
 int snd_pcm_format_set_silence(snd_pcm_format_t format, void *buf, unsigned int frames);
 snd_pcm_format_t snd_pcm_build_linear_format(int width, int unsigned, int big_endian);
 
-void snd_pcm_set_ops(struct snd_pcm * pcm, int direction, struct snd_pcm_ops *ops);
+void snd_pcm_set_ops(struct snd_pcm * pcm, int direction,
+                     const struct snd_pcm_ops *ops);
 void snd_pcm_set_sync(struct snd_pcm_substream *substream);
 int snd_pcm_lib_interleave_len(struct snd_pcm_substream *substream);
 int snd_pcm_lib_ioctl(struct snd_pcm_substream *substream,
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c
index 41b3dfe68698..82bb029d4414 100644
--- a/sound/core/pcm_lib.c
+++ b/sound/core/pcm_lib.c
@@ -568,7 +568,8 @@ int snd_pcm_update_hw_ptr(struct snd_pcm_substream *substream)
  *
  * Sets the given PCM operators to the pcm instance.
  */
-void snd_pcm_set_ops(struct snd_pcm *pcm, int direction, struct snd_pcm_ops *ops)
+void snd_pcm_set_ops(struct snd_pcm *pcm, int direction,
+                     const struct snd_pcm_ops *ops)
 {
         struct snd_pcm_str *stream = &pcm->streams[direction];
         struct snd_pcm_substream *substream;