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-rw-r--r--target/linux/brcm2708/patches-4.14/950-0410-bcm2835-interpolate-audio-delay.patch90
1 files changed, 0 insertions, 90 deletions
diff --git a/target/linux/brcm2708/patches-4.14/950-0410-bcm2835-interpolate-audio-delay.patch b/target/linux/brcm2708/patches-4.14/950-0410-bcm2835-interpolate-audio-delay.patch
deleted file mode 100644
index 2be6117ef6..0000000000
--- a/target/linux/brcm2708/patches-4.14/950-0410-bcm2835-interpolate-audio-delay.patch
+++ /dev/null
@@ -1,90 +0,0 @@
-From 84ad00eb76af34f8a6c6941dc6da80a3f735b207 Mon Sep 17 00:00:00 2001
-From: wm4 <wm4@nowhere>
-Date: Wed, 13 Jan 2016 19:44:47 +0100
-Subject: [PATCH 410/454] bcm2835: interpolate audio delay
-
-It appears the GPU only sends us a message all 10ms to update
-the playback progress. Other than this, the playback position
-(what SNDRV_PCM_IOCTL_DELAY will return) is not updated at all.
-Userspace will see jitter up to 10ms in the audio position.
-
-Make this a bit nicer for userspace by interpolating the
-position using the CPU clock.
-
-I'm not sure if setting snd_pcm_runtime.delay is the right
-approach for this. Or if there is maybe an already existing
-mechanism for position interpolation in the ALSA core.
-
-I only set SNDRV_PCM_INFO_BATCH because this appears to remove
-at least one situation snd_pcm_runtime.delay is used, so I have
-to worry less in which place I have to update this field, or
-how it interacts with the rest of ALSA.
-
-In the future, it might be nice to use VC_AUDIO_MSG_TYPE_LATENCY.
-One problem is that it requires sending a videocore message, and
-waiting for a reply, which could make the implementation much
-harder due to locking and synchronization requirements.
----
- .../vc04_services/bcm2835-audio/bcm2835-pcm.c | 13 +++++++++++--
- .../staging/vc04_services/bcm2835-audio/bcm2835.h | 1 +
- 2 files changed, 12 insertions(+), 2 deletions(-)
-
---- a/drivers/staging/vc04_services/bcm2835-audio/bcm2835-pcm.c
-+++ b/drivers/staging/vc04_services/bcm2835-audio/bcm2835-pcm.c
-@@ -22,7 +22,7 @@
- /* 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_MMAP | SNDRV_PCM_INFO_MMAP_VALID | SNDRV_PCM_INFO_BATCH),
- .formats = SNDRV_PCM_FMTBIT_U8 | SNDRV_PCM_FMTBIT_S16_LE,
- .rates = SNDRV_PCM_RATE_CONTINUOUS | SNDRV_PCM_RATE_8000_48000,
- .rate_min = 8000,
-@@ -93,6 +93,8 @@ 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);
-@@ -323,6 +325,7 @@ 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,
-@@ -415,13 +418,19 @@ 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
-@@ -137,6 +137,7 @@ 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;