staging: most: Use managed buffer allocation

Clean up the driver with the new managed buffer allocation API.
Also remove the unnecessary checks of channels in hw_params callback
as this is guaranteed by the hw constraints in anyway.
After these cleanups, the hw_params and hw_free callbacks became
empty, hence dropped.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://lore.kernel.org/r/20191210141356.18074-2-tiwai@suse.deSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/most/sound/sound.c

@@ -322,45 +322,6 @@ static int pcm_close(struct snd_pcm_substream *substream)
 	return 0;
 }
 
-/**
- * pcm_hw_params - implements hw_params callback function for PCM middle layer
- * @substream: sub-stream pointer
- * @hw_params: contains the hardware parameters set by the application
- *
- * This is called when the hardware parameters is set by the application, that
- * is, once when the buffer size, the period size, the format, etc. are defined
- * for the PCM substream. Many hardware setups should be done is this callback,
- * including the allocation of buffers.
- *
- * Returns 0 on success or error code otherwise.
- */
-static int pcm_hw_params(struct snd_pcm_substream *substream,
-			 struct snd_pcm_hw_params *hw_params)
-{
-	struct channel *channel = substream->private_data;
-
-	if ((params_channels(hw_params) > channel->pcm_hardware.channels_max) ||
-	    (params_channels(hw_params) < channel->pcm_hardware.channels_min)) {
-		pr_err("Requested number of channels not supported.\n");
-		return -EINVAL;
-	}
-	return snd_pcm_lib_malloc_pages(substream, params_buffer_bytes(hw_params));
-}
-
-/**
- * pcm_hw_free - implements hw_free callback function for PCM middle layer
- * @substream: substream pointer
- *
- * This is called to release the resources allocated via hw_params.
- * This function will be always called before the close callback is called.
- *
- * Returns 0 on success or error code otherwise.
- */
-static int pcm_hw_free(struct snd_pcm_substream *substream)
-{
-	return snd_pcm_lib_free_pages(substream);
-}
-
 /**
  * pcm_prepare - implements prepare callback function for PCM middle layer
  * @substream: substream pointer
@@ -463,8 +424,6 @@ static const struct snd_pcm_ops pcm_ops = {
 	.open       = pcm_open,
 	.close      = pcm_close,
 	.ioctl      = snd_pcm_lib_ioctl,
-	.hw_params  = pcm_hw_params,
-	.hw_free    = pcm_hw_free,
 	.prepare    = pcm_prepare,
 	.trigger    = pcm_trigger,
 	.pointer    = pcm_pointer,
@@ -661,8 +620,7 @@ static int audio_probe_channel(struct most_interface *iface, int channel_id,
 	pcm->private_data = channel;
 	strscpy(pcm->name, device_name, sizeof(pcm->name));
 	snd_pcm_set_ops(pcm, direction, &pcm_ops);
-	snd_pcm_lib_preallocate_pages_for_all(pcm, SNDRV_DMA_TYPE_VMALLOC,
-					      NULL, 0, 0);
+	snd_pcm_set_managed_buffer_all(pcm, SNDRV_DMA_TYPE_VMALLOC, NULL, 0, 0);
 
 	return 0;