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.
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| @@ -710,7 +710,7 @@ enum { · 709 unmodified lines | |||
| 710 | * Raw MIDI section - /dev/snd/midi?? | 710 | * Raw MIDI section - /dev/snd/midi?? |
| 711 | */ | 711 | */ |
| 712 | 712 | ||
| 713 | #define SNDRV_RAWMIDI_VERSION SNDRV_PROTOCOL_VERSION(2, 0, 1) | 713 | #define SNDRV_RAWMIDI_VERSION SNDRV_PROTOCOL_VERSION(2, 0, 2) |
| 714 | 714 | ||
| 715 | enum { | 715 | enum { |
| 716 | SNDRV_RAWMIDI_STREAM_OUTPUT = 0, | 716 | SNDRV_RAWMIDI_STREAM_OUTPUT = 0, |
| @@ -736,12 +736,38 @@ struct snd_rawmidi_info { · 19 unmodified lines | |||
| 736 | unsigned char reserved[64]; /* reserved for future use */ | 736 | unsigned char reserved[64]; /* reserved for future use */ |
| 737 | }; | 737 | }; |
| 738 | 738 | ||
| 739 | #define SNDRV_RAWMIDI_MODE_FRAMING_MASK (7<<0) | ||
| 740 | #define SNDRV_RAWMIDI_MODE_FRAMING_SHIFT 0 | ||
| 741 | #define SNDRV_RAWMIDI_MODE_FRAMING_NONE (0<<0) | ||
| 742 | #define SNDRV_RAWMIDI_MODE_FRAMING_TSTAMP (1<<0) | ||
| 743 | #define SNDRV_RAWMIDI_MODE_CLOCK_MASK (7<<3) | ||
| 744 | #define SNDRV_RAWMIDI_MODE_CLOCK_SHIFT 3 | ||
| 745 | #define SNDRV_RAWMIDI_MODE_CLOCK_NONE (0<<3) | ||
| 746 | #define SNDRV_RAWMIDI_MODE_CLOCK_REALTIME (1<<3) | ||
| 747 | #define SNDRV_RAWMIDI_MODE_CLOCK_MONOTONIC (2<<3) | ||
| 748 | #define SNDRV_RAWMIDI_MODE_CLOCK_MONOTONIC_RAW (3<<3) | ||
| 749 | |||
| 750 | #define SNDRV_RAWMIDI_FRAMING_DATA_LENGTH 16 | ||
| 751 | |||
| 752 | struct snd_rawmidi_framing_tstamp { | ||
| 753 | /* For now, frame_type is always 0. Midi 2.0 is expected to add new | ||
| 754 | * types here. Applications are expected to skip unknown frame types. | ||
| 755 | */ | ||
| 756 | __u8 frame_type; | ||
| 757 | __u8 length; /* number of valid bytes in data field */ | ||
| 758 | __u8 reserved[2]; | ||
| 759 | __u32 tv_nsec; /* nanoseconds */ | ||
| 760 | __u64 tv_sec; /* seconds */ | ||
| 761 | __u8 data[SNDRV_RAWMIDI_FRAMING_DATA_LENGTH]; | ||
| 762 | } __packed; | ||
| 763 | |||
| 739 | struct snd_rawmidi_params { | 764 | struct snd_rawmidi_params { |
| 740 | int stream; | 765 | int stream; |
| 741 | size_t buffer_size; /* queue size in bytes */ | 766 | size_t buffer_size; /* queue size in bytes */ |
| 742 | size_t avail_min; /* minimum avail bytes for wakeup */ | 767 | size_t avail_min; /* minimum avail bytes for wakeup */ |
| 743 | unsigned int no_active_sensing: 1; /* do not send active sensing byte in close() */ | 768 | unsigned int no_active_sensing: 1; /* do not send active sensing byte in close() */ |
| 744 | unsigned char reserved[16]; /* reserved for future use */ | 769 | unsigned int mode; /* For input data only, frame incoming data */ |
| 770 | unsigned char reserved[12]; /* reserved for future use */ | ||
| 745 | }; | 771 | }; |
| 746 | 772 | ||
| 747 | #ifndef __KERNEL__ | 773 | #ifndef __KERNEL__ |