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authorDavid Henningsson <coding@diwic.se>2021-05-15 10:15:33 +0300
committerTakashi Iwai <tiwai@suse.de>2021-05-17 17:02:44 +0300
commit08fdced60ca08e34e316a3ab945636fcdfcbc973 (patch)
tree2ebf36f380c9bafbb78b43bb32de7118c8f4d529 /sound/core/rawmidi.c
parentbac59054544ebdb89f05c5b9598ca9cb2dea72ce (diff)
downloadlinux-08fdced60ca08e34e316a3ab945636fcdfcbc973.tar.xz
ALSA: rawmidi: Add framing mode
This commit adds a new framing mode that frames all MIDI data into 32-byte frames with a timestamp. The main benefit is that we can get accurate timestamps even if userspace wakeup and processing is not immediate. Testing on a Celeron N3150 with this mode has a max jitter of 2.8 ms, compared to the in-kernel seq implementation which has a max jitter of 5 ms during idle and much worse when running scheduler stress tests in parallel. Signed-off-by: David Henningsson <coding@diwic.se> Reviewed-by: Jaroslav Kysela <perex@perex.cz> Link: https://lore.kernel.org/r/20210515071533.55332-1-coding@diwic.se Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound/core/rawmidi.c')
-rw-r--r--sound/core/rawmidi.c93
1 files changed, 91 insertions, 2 deletions
diff --git a/sound/core/rawmidi.c b/sound/core/rawmidi.c
index aca00af93afe..4a6534db77d6 100644
--- a/sound/core/rawmidi.c
+++ b/sound/core/rawmidi.c
@@ -680,9 +680,12 @@ static int resize_runtime_buffer(struct snd_rawmidi_runtime *runtime,
bool is_input)
{
char *newbuf, *oldbuf;
+ unsigned int framing = params->mode & SNDRV_RAWMIDI_MODE_FRAMING_MASK;
if (params->buffer_size < 32 || params->buffer_size > 1024L * 1024L)
return -EINVAL;
+ if (framing == SNDRV_RAWMIDI_MODE_FRAMING_TSTAMP && (params->buffer_size & 0x1f) != 0)
+ return -EINVAL;
if (params->avail_min < 1 || params->avail_min > params->buffer_size)
return -EINVAL;
if (params->buffer_size != runtime->buffer_size) {
@@ -720,8 +723,24 @@ EXPORT_SYMBOL(snd_rawmidi_output_params);
int snd_rawmidi_input_params(struct snd_rawmidi_substream *substream,
struct snd_rawmidi_params *params)
{
+ unsigned int framing = params->mode & SNDRV_RAWMIDI_MODE_FRAMING_MASK;
+ unsigned int clock_type = params->mode & SNDRV_RAWMIDI_MODE_CLOCK_MASK;
+ int err;
+
+ if (framing == SNDRV_RAWMIDI_MODE_FRAMING_NONE && clock_type != SNDRV_RAWMIDI_MODE_CLOCK_NONE)
+ return -EINVAL;
+ else if (clock_type > SNDRV_RAWMIDI_MODE_CLOCK_MONOTONIC_RAW)
+ return -EINVAL;
+ if (framing > SNDRV_RAWMIDI_MODE_FRAMING_TSTAMP)
+ return -EINVAL;
snd_rawmidi_drain_input(substream);
- return resize_runtime_buffer(substream->runtime, params, true);
+ err = resize_runtime_buffer(substream->runtime, params, true);
+ if (err < 0)
+ return err;
+
+ substream->framing = framing;
+ substream->clock_type = clock_type;
+ return 0;
}
EXPORT_SYMBOL(snd_rawmidi_input_params);
@@ -963,6 +982,62 @@ static int snd_rawmidi_control_ioctl(struct snd_card *card,
return -ENOIOCTLCMD;
}
+static int receive_with_tstamp_framing(struct snd_rawmidi_substream *substream,
+ const unsigned char *buffer, int src_count, const struct timespec64 *tstamp)
+{
+ struct snd_rawmidi_runtime *runtime = substream->runtime;
+ struct snd_rawmidi_framing_tstamp *dest_ptr;
+ struct snd_rawmidi_framing_tstamp frame = { .tv_sec = tstamp->tv_sec, .tv_nsec = tstamp->tv_nsec };
+ int dest_frames = 0;
+ int orig_count = src_count;
+ int frame_size = sizeof(struct snd_rawmidi_framing_tstamp);
+
+ BUILD_BUG_ON(frame_size != 0x20);
+ if (snd_BUG_ON((runtime->hw_ptr & 0x1f) != 0))
+ return -EINVAL;
+
+ while (src_count > 0) {
+ if ((int)(runtime->buffer_size - runtime->avail) < frame_size) {
+ runtime->xruns += src_count;
+ break;
+ }
+ if (src_count >= SNDRV_RAWMIDI_FRAMING_DATA_LENGTH)
+ frame.length = SNDRV_RAWMIDI_FRAMING_DATA_LENGTH;
+ else {
+ frame.length = src_count;
+ memset(frame.data, 0, SNDRV_RAWMIDI_FRAMING_DATA_LENGTH);
+ }
+ memcpy(frame.data, buffer, frame.length);
+ buffer += frame.length;
+ src_count -= frame.length;
+ dest_ptr = (struct snd_rawmidi_framing_tstamp *) (runtime->buffer + runtime->hw_ptr);
+ *dest_ptr = frame;
+ runtime->avail += frame_size;
+ runtime->hw_ptr += frame_size;
+ runtime->hw_ptr %= runtime->buffer_size;
+ dest_frames++;
+ }
+ return orig_count - src_count;
+}
+
+static struct timespec64 get_framing_tstamp(struct snd_rawmidi_substream *substream)
+{
+ struct timespec64 ts64 = {0, 0};
+
+ switch (substream->clock_type) {
+ case SNDRV_RAWMIDI_MODE_CLOCK_MONOTONIC_RAW:
+ ktime_get_raw_ts64(&ts64);
+ break;
+ case SNDRV_RAWMIDI_MODE_CLOCK_MONOTONIC:
+ ktime_get_ts64(&ts64);
+ break;
+ case SNDRV_RAWMIDI_MODE_CLOCK_REALTIME:
+ ktime_get_real_ts64(&ts64);
+ break;
+ }
+ return ts64;
+}
+
/**
* snd_rawmidi_receive - receive the input data from the device
* @substream: the rawmidi substream
@@ -977,6 +1052,7 @@ int snd_rawmidi_receive(struct snd_rawmidi_substream *substream,
const unsigned char *buffer, int count)
{
unsigned long flags;
+ struct timespec64 ts64 = get_framing_tstamp(substream);
int result = 0, count1;
struct snd_rawmidi_runtime *runtime = substream->runtime;
@@ -987,8 +1063,11 @@ int snd_rawmidi_receive(struct snd_rawmidi_substream *substream,
"snd_rawmidi_receive: input is not active!!!\n");
return -EINVAL;
}
+
spin_lock_irqsave(&runtime->lock, flags);
- if (count == 1) { /* special case, faster code */
+ if (substream->framing == SNDRV_RAWMIDI_MODE_FRAMING_TSTAMP) {
+ result = receive_with_tstamp_framing(substream, buffer, count, &ts64);
+ } else if (count == 1) { /* special case, faster code */
substream->bytes++;
if (runtime->avail < runtime->buffer_size) {
runtime->buffer[runtime->hw_ptr++] = buffer[0];
@@ -1541,6 +1620,8 @@ static void snd_rawmidi_proc_info_read(struct snd_info_entry *entry,
struct snd_rawmidi_substream *substream;
struct snd_rawmidi_runtime *runtime;
unsigned long buffer_size, avail, xruns;
+ unsigned int clock_type;
+ static const char *clock_names[4] = { "none", "realtime", "monotonic", "monotonic raw" };
rmidi = entry->private_data;
snd_iprintf(buffer, "%s\n\n", rmidi->name);
@@ -1596,6 +1677,14 @@ static void snd_rawmidi_proc_info_read(struct snd_info_entry *entry,
" Avail : %lu\n"
" Overruns : %lu\n",
buffer_size, avail, xruns);
+ if (substream->framing == SNDRV_RAWMIDI_MODE_FRAMING_TSTAMP) {
+ clock_type = substream->clock_type >> SNDRV_RAWMIDI_MODE_CLOCK_SHIFT;
+ if (!snd_BUG_ON(clock_type >= sizeof(clock_names)))
+ snd_iprintf(buffer,
+ " Framing : tstamp\n"
+ " Clock type : %s\n",
+ clock_names[clock_type]);
+ }
}
}
}