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path: root/target/linux/brcm2708/patches-4.19/950-0437-Revert-bcm2835-interpolate-audio-delay.patch
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From fe6afd9a110a042d2f00934b3a95ae57471f18cf Mon Sep 17 00:00:00 2001
From: popcornmix <popcornmix@gmail.com>
Date: Mon, 29 Apr 2019 19:16:14 +0100
Subject: [PATCH 437/703] Revert "bcm2835: interpolate audio delay"

commit fb4b9f02986fcb5ae751106ef9b027806b5dd750 upstream.

This reverts commit fb8cc99f05687ca5565dc53a7ee0dd86aefad952.
---
 .../vc04_services/bcm2835-audio/bcm2835-pcm.c        | 12 +-----------
 .../staging/vc04_services/bcm2835-audio/bcm2835.h    |  1 -
 2 files changed, 1 insertion(+), 12 deletions(-)

--- a/drivers/staging/vc04_services/bcm2835-audio/bcm2835-pcm.c
+++ b/drivers/staging/vc04_services/bcm2835-audio/bcm2835-pcm.c
@@ -11,7 +11,7 @@
 /* hardware definition */
 static const 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,
@@ -81,8 +81,6 @@ void bcm2835_playback_fifo(struct bcm283
 		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);
@@ -308,7 +306,6 @@ static int snd_bcm2835_pcm_prepare(struc
 	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,
@@ -400,19 +397,12 @@ snd_bcm2835_pcm_pointer(struct snd_pcm_s
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	struct bcm2835_alsa_stream *alsa_stream = runtime->private_data;
-	u64 now = ktime_get_ns();
 
 	audio_debug("pcm_pointer... (%d) hwptr=%d appl=%d pos=%d\n", 0,
 		frames_to_bytes(runtime, runtime->status->hw_ptr),
 		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);
-
 	return snd_pcm_indirect_playback_pointer(substream,
 		&alsa_stream->pcm_indirect,
 		alsa_stream->pos);
--- a/drivers/staging/vc04_services/bcm2835-audio/bcm2835.h
+++ b/drivers/staging/vc04_services/bcm2835-audio/bcm2835.h
@@ -133,7 +133,6 @@ struct bcm2835_alsa_stream {
 	unsigned int pos;
 	unsigned int buffer_size;
 	unsigned int period_size;
-	u64 interpolate_start;
 
 	atomic_t retrieved;
 	struct bcm2835_audio_instance *instance;