Revert "bcm2835: interpolate audio delay"

This reverts commit 83eca61.

Author: popcornmix

sound/arm/bcm2835-pcm.c

@@ -25,7 +25,7 @@
 /* hardware definition */
 static struct snd_pcm_hardware snd_bcm2835_playback_hw = {
 	.info = (SNDRV_PCM_INFO_INTERLEAVED | SNDRV_PCM_INFO_BLOCK_TRANSFER |
-		 SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_MMAP_VALID | SNDRV_PCM_INFO_BATCH),
+		 SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_MMAP_VALID),
 	.formats = SNDRV_PCM_FMTBIT_U8 | SNDRV_PCM_FMTBIT_S16_LE,
 	.rates = SNDRV_PCM_RATE_CONTINUOUS | SNDRV_PCM_RATE_8000_48000,
 	.rate_min = 8000,
@@ -99,8 +99,6 @@ static irqreturn_t bcm2835_playback_fifo_irq(int irq, void *dev_id)
 		alsa_stream->pos %= alsa_stream->buffer_size;
 	}
 
-	alsa_stream->interpolate_start = ktime_get_ns();
-
 	if (alsa_stream->substream) {
 		if (new_period)
 			snd_pcm_period_elapsed(alsa_stream->substream);
@@ -401,7 +399,6 @@ static int snd_bcm2835_pcm_prepare(struct snd_pcm_substream *substream)
 	alsa_stream->buffer_size = snd_pcm_lib_buffer_bytes(substream);
 	alsa_stream->period_size = snd_pcm_lib_period_bytes(substream);
 	alsa_stream->pos = 0;
-	alsa_stream->interpolate_start = ktime_get_ns();
 
 	audio_debug("buffer_size=%d, period_size=%d pos=%d frame_bits=%d\n",
 		      alsa_stream->buffer_size, alsa_stream->period_size,
@@ -498,7 +495,6 @@ snd_bcm2835_pcm_pointer(struct snd_pcm_substream *substream)
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	bcm2835_alsa_stream_t *alsa_stream = runtime->private_data;
-	u64 now = ktime_get_ns();
 
 	audio_info(" .. IN\n");
 
@@ -507,12 +503,6 @@ snd_bcm2835_pcm_pointer(struct snd_pcm_substream *substream)
 		      frames_to_bytes(runtime, runtime->control->appl_ptr),
 		      alsa_stream->pos);
 
-	/* Give userspace better delay reporting by interpolating between GPU
-	 * notifications, assuming audio speed is close enough to the clock
-	 * used for ktime */
-	if (alsa_stream->interpolate_start && alsa_stream->interpolate_start < now)
-		runtime->delay = -(int)div_u64((now - alsa_stream->interpolate_start) * runtime->rate,  1000000000);
-
 	audio_info(" .. OUT\n");
 	return snd_pcm_indirect_playback_pointer(substream,
 						 &alsa_stream->pcm_indirect,

sound/arm/bcm2835.h

@@ -137,7 +137,6 @@ typedef struct bcm2835_alsa_stream {
 	unsigned int pos;
 	unsigned int buffer_size;
 	unsigned int period_size;
-	u64 interpolate_start;
 
 	uint32_t enable_fifo_irq;
 	irq_handler_t fifo_irq_handler;