ALSA: aloop: Use managed buffer allocation

Clean up the driver with the new managed buffer allocation API.
The hw_params callback became superfluous and got dropped.

Link: https://lore.kernel.org/r/20191209094943.14984-5-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/drivers/aloop.c

@@ -905,12 +905,6 @@ static void loopback_runtime_free(struct snd_pcm_runtime *runtime)
 	kfree(dpcm);
 }
 
-static int loopback_hw_params(struct snd_pcm_substream *substream,
-			      struct snd_pcm_hw_params *params)
-{
-	return snd_pcm_lib_malloc_pages(substream, params_buffer_bytes(params));
-}
-
 static int loopback_hw_free(struct snd_pcm_substream *substream)
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
@@ -920,7 +914,7 @@ static int loopback_hw_free(struct snd_pcm_substream *substream)
 	mutex_lock(&dpcm->loopback->cable_lock);
 	cable->valid &= ~(1 << substream->stream);
 	mutex_unlock(&dpcm->loopback->cable_lock);
-	return snd_pcm_lib_free_pages(substream);
+	return 0;
 }
 
 static unsigned int get_cable_index(struct snd_pcm_substream *substream)
@@ -1306,7 +1300,6 @@ static const struct snd_pcm_ops loopback_pcm_ops = {
 	.open =		loopback_open,
 	.close =	loopback_close,
 	.ioctl =	snd_pcm_lib_ioctl,
-	.hw_params =	loopback_hw_params,
 	.hw_free =	loopback_hw_free,
 	.prepare =	loopback_prepare,
 	.trigger =	loopback_trigger,
@@ -1325,8 +1318,7 @@ static int loopback_pcm_new(struct loopback *loopback,
 		return err;
 	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &loopback_pcm_ops);
 	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &loopback_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);
 
 	pcm->private_data = loopback;
 	pcm->info_flags = 0;