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| author | David Henningsson <coding@diwic.se> | 2021-05-15 10:15:33 +0300 |
|---|---|---|
| committer | Takashi Iwai <tiwai@suse.de> | 2021-05-17 17:02:44 +0300 |
| commit | 08fdced60ca08e34e316a3ab945636fcdfcbc973 (patch) | |
| tree | 2ebf36f380c9bafbb78b43bb32de7118c8f4d529 /sound/core/rawmidi_compat.c | |
| parent | bac59054544ebdb89f05c5b9598ca9cb2dea72ce (diff) | |
| download | linux-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_compat.c')
| -rw-r--r-- | sound/core/rawmidi_compat.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/sound/core/rawmidi_compat.c b/sound/core/rawmidi_compat.c index 7397130976d0..68a93443583c 100644 --- a/sound/core/rawmidi_compat.c +++ b/sound/core/rawmidi_compat.c @@ -13,7 +13,8 @@ struct snd_rawmidi_params32 { u32 buffer_size; u32 avail_min; unsigned int no_active_sensing; /* avoid bit-field */ - unsigned char reserved[16]; + unsigned int mode; + unsigned char reserved[12]; } __attribute__((packed)); static int snd_rawmidi_ioctl_params_compat(struct snd_rawmidi_file *rfile, @@ -25,6 +26,7 @@ static int snd_rawmidi_ioctl_params_compat(struct snd_rawmidi_file *rfile, if (get_user(params.stream, &src->stream) || get_user(params.buffer_size, &src->buffer_size) || get_user(params.avail_min, &src->avail_min) || + get_user(params.mode, &src->mode) || get_user(val, &src->no_active_sensing)) return -EFAULT; params.no_active_sensing = val; |