294c4fb8ab
Existing code only updates the audio delay when URBs were submitted/retired. This can introduce an uncertainty of 8ms on the number of samples played out with the default settings, and a lot more when URBs convey more packets to reduce the interrupt rate and power consumption. This patch relies on the USB frame counter to reduce the uncertainty to less than 2ms worst-case. The delay information essentially becomes independent of the URB size and number of packets. This should help applications like PulseAudio which require accurate audio timing. Clemens Ladisch reported a decrease of mplayer's A-V difference from nrpacks down to at most 1ms. Thanks to Clemens for also pointing out that the implementation of frame counters varies between different HCDs. Only the 8 lowest-bits are used to estimate the delay. Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com> [clemens: changed debug code] Signed-off-by: Clemens Ladisch <clemens@ladisch.de> Signed-off-by: Takashi Iwai <tiwai@suse.de>
111 lines
4.8 KiB
C
111 lines
4.8 KiB
C
#ifndef __USBAUDIO_CARD_H
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#define __USBAUDIO_CARD_H
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#define MAX_PACKS 20
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#define MAX_PACKS_HS (MAX_PACKS * 8) /* in high speed mode */
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#define MAX_URBS 8
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#define SYNC_URBS 4 /* always four urbs for sync */
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#define MAX_QUEUE 24 /* try not to exceed this queue length, in ms */
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struct audioformat {
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struct list_head list;
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u64 formats; /* ALSA format bits */
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unsigned int channels; /* # channels */
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unsigned int fmt_type; /* USB audio format type (1-3) */
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unsigned int frame_size; /* samples per frame for non-audio */
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int iface; /* interface number */
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unsigned char altsetting; /* corresponding alternate setting */
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unsigned char altset_idx; /* array index of altenate setting */
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unsigned char attributes; /* corresponding attributes of cs endpoint */
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unsigned char endpoint; /* endpoint */
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unsigned char ep_attr; /* endpoint attributes */
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unsigned char datainterval; /* log_2 of data packet interval */
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unsigned int maxpacksize; /* max. packet size */
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unsigned int rates; /* rate bitmasks */
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unsigned int rate_min, rate_max; /* min/max rates */
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unsigned int nr_rates; /* number of rate table entries */
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unsigned int *rate_table; /* rate table */
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unsigned char clock; /* associated clock */
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};
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struct snd_usb_substream;
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struct snd_urb_ctx {
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struct urb *urb;
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unsigned int buffer_size; /* size of data buffer, if data URB */
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struct snd_usb_substream *subs;
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int index; /* index for urb array */
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int packets; /* number of packets per urb */
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};
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struct snd_urb_ops {
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int (*prepare)(struct snd_usb_substream *subs, struct snd_pcm_runtime *runtime, struct urb *u);
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int (*retire)(struct snd_usb_substream *subs, struct snd_pcm_runtime *runtime, struct urb *u);
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int (*prepare_sync)(struct snd_usb_substream *subs, struct snd_pcm_runtime *runtime, struct urb *u);
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int (*retire_sync)(struct snd_usb_substream *subs, struct snd_pcm_runtime *runtime, struct urb *u);
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};
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struct snd_usb_substream {
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struct snd_usb_stream *stream;
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struct usb_device *dev;
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struct snd_pcm_substream *pcm_substream;
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int direction; /* playback or capture */
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int interface; /* current interface */
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int endpoint; /* assigned endpoint */
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struct audioformat *cur_audiofmt; /* current audioformat pointer (for hw_params callback) */
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unsigned int cur_rate; /* current rate (for hw_params callback) */
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unsigned int period_bytes; /* current period bytes (for hw_params callback) */
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unsigned int altset_idx; /* USB data format: index of alternate setting */
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unsigned int datapipe; /* the data i/o pipe */
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unsigned int syncpipe; /* 1 - async out or adaptive in */
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unsigned int datainterval; /* log_2 of data packet interval */
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unsigned int syncinterval; /* P for adaptive mode, 0 otherwise */
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unsigned int freqn; /* nominal sampling rate in fs/fps in Q16.16 format */
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unsigned int freqm; /* momentary sampling rate in fs/fps in Q16.16 format */
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int freqshift; /* how much to shift the feedback value to get Q16.16 */
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unsigned int freqmax; /* maximum sampling rate, used for buffer management */
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unsigned int phase; /* phase accumulator */
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unsigned int maxpacksize; /* max packet size in bytes */
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unsigned int maxframesize; /* max packet size in frames */
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unsigned int curpacksize; /* current packet size in bytes (for capture) */
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unsigned int curframesize; /* current packet size in frames (for capture) */
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unsigned int syncmaxsize; /* sync endpoint packet size */
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unsigned int fill_max: 1; /* fill max packet size always */
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unsigned int txfr_quirk:1; /* allow sub-frame alignment */
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unsigned int fmt_type; /* USB audio format type (1-3) */
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unsigned int running: 1; /* running status */
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unsigned int hwptr_done; /* processed byte position in the buffer */
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unsigned int transfer_done; /* processed frames since last period update */
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unsigned long active_mask; /* bitmask of active urbs */
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unsigned long unlink_mask; /* bitmask of unlinked urbs */
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unsigned int nurbs; /* # urbs */
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struct snd_urb_ctx dataurb[MAX_URBS]; /* data urb table */
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struct snd_urb_ctx syncurb[SYNC_URBS]; /* sync urb table */
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char *syncbuf; /* sync buffer for all sync URBs */
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dma_addr_t sync_dma; /* DMA address of syncbuf */
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u64 formats; /* format bitmasks (all or'ed) */
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unsigned int num_formats; /* number of supported audio formats (list) */
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struct list_head fmt_list; /* format list */
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struct snd_pcm_hw_constraint_list rate_list; /* limited rates */
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spinlock_t lock;
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struct snd_urb_ops ops; /* callbacks (must be filled at init) */
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int last_frame_number; /* stored frame number */
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int last_delay; /* stored delay */
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};
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struct snd_usb_stream {
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struct snd_usb_audio *chip;
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struct snd_pcm *pcm;
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int pcm_index;
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unsigned int fmt_type; /* USB audio format type (1-3) */
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struct snd_usb_substream substream[2];
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struct list_head list;
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};
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#endif /* __USBAUDIO_CARD_H */
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