brcm2708: organize kernel patches

[openwrt/staging/dedeckeh.git] / target / linux / brcm2708 / patches-4.19 / 950-0470-staging-bcm2835-audio-interpolate-audio-delay.patch

diff --git a/target/linux/brcm2708/patches-4.19/950-0470-staging-bcm2835-audio-interpolate-audio-delay.patch b/target/linux/brcm2708/patches-4.19/950-0470-staging-bcm2835-audio-interpolate-audio-delay.patch
deleted file mode 100644 (file)
index d5da293..0000000
--- a/target/linux/brcm2708/patches-4.19/950-0470-staging-bcm2835-audio-interpolate-audio-delay.patch
+++ /dev/null
@@ -1,82 +0,0 @@
-From 2ba82d9516203ce41f33e98adb667bedee3622bc Mon Sep 17 00:00:00 2001
-From: Mike Brady <mikebrady@eircom.net>
-Date: Mon, 22 Oct 2018 20:17:08 +0100
-Subject: [PATCH 470/806] staging: bcm2835-audio: interpolate audio delay
-
-commit a105a3a72824e0ac685a0711a67e4dbe29de62d0 upstream.
-
-When the BCM2835 audio output is used, userspace sees a jitter up to 10ms
-in the audio position, aka "delay" -- the number of frames that must
-be output before a new frame would be played.
-Make this a bit nicer for userspace by interpolating the position
-using the CPU clock.
-The overhead is small -- an extra ktime_get() every time a GPU message
-is sent -- and another call and a few calculations whenever the delay
-is sought from userland.
-At 48,000 frames per second, i.e. approximately 20 microseconds per
-frame, it would take a clock inaccuracy of
-20 microseconds in 10 milliseconds -- 2,000 parts per million --
-to result in an inaccurate estimate, whereas
-crystal- or resonator-based clocks typically have an
-inaccuracy of 10s to 100s of parts per million.
-
-Signed-off-by: Mike Brady <mikebrady@eircom.net>
-Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
----
- .../vc04_services/bcm2835-audio/bcm2835-pcm.c | 20 +++++++++++++++++++
- .../vc04_services/bcm2835-audio/bcm2835.h     |  1 +
- 2 files changed, 21 insertions(+)
-
---- a/drivers/staging/vc04_services/bcm2835-audio/bcm2835-pcm.c
-+++ b/drivers/staging/vc04_services/bcm2835-audio/bcm2835-pcm.c
-@@ -74,6 +74,7 @@ void bcm2835_playback_fifo(struct bcm283
-       atomic_set(&alsa_stream->pos, pos);
- 
-       alsa_stream->period_offset += bytes;
-+      alsa_stream->interpolate_start = ktime_get();
-       if (alsa_stream->period_offset >= alsa_stream->period_size) {
-               alsa_stream->period_offset %= alsa_stream->period_size;
-               snd_pcm_period_elapsed(substream);
-@@ -237,6 +238,7 @@ static int snd_bcm2835_pcm_prepare(struc
-       atomic_set(&alsa_stream->pos, 0);
-       alsa_stream->period_offset = 0;
-       alsa_stream->draining = false;
-+      alsa_stream->interpolate_start = ktime_get();
- 
-       return 0;
- }
-@@ -286,6 +288,24 @@ snd_bcm2835_pcm_pointer(struct snd_pcm_s
- {
-       struct snd_pcm_runtime *runtime = substream->runtime;
-       struct bcm2835_alsa_stream *alsa_stream = runtime->private_data;
-+      ktime_t now = ktime_get();
-+
-+      /* Give userspace better delay reporting by interpolating between GPU
-+       * notifications, assuming audio speed is close enough to the clock
-+       * used for ktime
-+       */
-+
-+      if ((ktime_to_ns(alsa_stream->interpolate_start)) &&
-+          (ktime_compare(alsa_stream->interpolate_start, now) < 0)) {
-+              u64 interval =
-+                      (ktime_to_ns(ktime_sub(now,
-+                              alsa_stream->interpolate_start)));
-+              u64 frames_output_in_interval =
-+                      div_u64((interval * runtime->rate), 1000000000);
-+              snd_pcm_sframes_t frames_output_in_interval_sized =
-+                      -frames_output_in_interval;
-+              runtime->delay = frames_output_in_interval_sized;
-+      }
- 
-       return snd_pcm_indirect_playback_pointer(substream,
-               &alsa_stream->pcm_indirect,
---- a/drivers/staging/vc04_services/bcm2835-audio/bcm2835.h
-+++ b/drivers/staging/vc04_services/bcm2835-audio/bcm2835.h
-@@ -78,6 +78,7 @@ struct bcm2835_alsa_stream {
-       unsigned int period_offset;
-       unsigned int buffer_size;
-       unsigned int period_size;
-+      ktime_t interpolate_start;
- 
-       struct bcm2835_audio_instance *instance;
-       int idx;