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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 /include
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 'include')
-rw-r--r--include/sound/rawmidi.h2
-rw-r--r--include/uapi/sound/asound.h30
2 files changed, 30 insertions, 2 deletions
diff --git a/include/sound/rawmidi.h b/include/sound/rawmidi.h
index 334842daa904..989e1517332d 100644
--- a/include/sound/rawmidi.h
+++ b/include/sound/rawmidi.h
@@ -81,6 +81,8 @@ struct snd_rawmidi_substream {
bool opened; /* open flag */
bool append; /* append flag (merge more streams) */
bool active_sensing; /* send active sensing when close */
+ unsigned int framing; /* whether to frame input data */
+ unsigned int clock_type; /* clock source to use for input framing */
int use_count; /* use counter (for output) */
size_t bytes;
struct snd_rawmidi *rmidi;
diff --git a/include/uapi/sound/asound.h b/include/uapi/sound/asound.h
index 535a7229e1d9..d17c061950df 100644
--- a/include/uapi/sound/asound.h
+++ b/include/uapi/sound/asound.h
@@ -710,7 +710,7 @@ enum {
* Raw MIDI section - /dev/snd/midi??
*/
-#define SNDRV_RAWMIDI_VERSION SNDRV_PROTOCOL_VERSION(2, 0, 1)
+#define SNDRV_RAWMIDI_VERSION SNDRV_PROTOCOL_VERSION(2, 0, 2)
enum {
SNDRV_RAWMIDI_STREAM_OUTPUT = 0,
@@ -736,12 +736,38 @@ struct snd_rawmidi_info {
unsigned char reserved[64]; /* reserved for future use */
};
+#define SNDRV_RAWMIDI_MODE_FRAMING_MASK (7<<0)
+#define SNDRV_RAWMIDI_MODE_FRAMING_SHIFT 0
+#define SNDRV_RAWMIDI_MODE_FRAMING_NONE (0<<0)
+#define SNDRV_RAWMIDI_MODE_FRAMING_TSTAMP (1<<0)
+#define SNDRV_RAWMIDI_MODE_CLOCK_MASK (7<<3)
+#define SNDRV_RAWMIDI_MODE_CLOCK_SHIFT 3
+#define SNDRV_RAWMIDI_MODE_CLOCK_NONE (0<<3)
+#define SNDRV_RAWMIDI_MODE_CLOCK_REALTIME (1<<3)
+#define SNDRV_RAWMIDI_MODE_CLOCK_MONOTONIC (2<<3)
+#define SNDRV_RAWMIDI_MODE_CLOCK_MONOTONIC_RAW (3<<3)
+
+#define SNDRV_RAWMIDI_FRAMING_DATA_LENGTH 16
+
+struct snd_rawmidi_framing_tstamp {
+ /* For now, frame_type is always 0. Midi 2.0 is expected to add new
+ * types here. Applications are expected to skip unknown frame types.
+ */
+ __u8 frame_type;
+ __u8 length; /* number of valid bytes in data field */
+ __u8 reserved[2];
+ __u32 tv_nsec; /* nanoseconds */
+ __u64 tv_sec; /* seconds */
+ __u8 data[SNDRV_RAWMIDI_FRAMING_DATA_LENGTH];
+} __packed;
+
struct snd_rawmidi_params {
int stream;
size_t buffer_size; /* queue size in bytes */
size_t avail_min; /* minimum avail bytes for wakeup */
unsigned int no_active_sensing: 1; /* do not send active sensing byte in close() */
- unsigned char reserved[16]; /* reserved for future use */
+ unsigned int mode; /* For input data only, frame incoming data */
+ unsigned char reserved[12]; /* reserved for future use */
};
#ifndef __KERNEL__