diff options
| author | Clemens Ladisch <clemens@ladisch.de> | 2005-08-12 15:19:39 +0200 |
|---|---|---|
| committer | Jaroslav Kysela <perex@suse.cz> | 2005-08-30 08:45:16 +0200 |
| commit | a93bf99077886d209f8e72bc134e1ceb36e76aa2 (patch) | |
| tree | a26ba330656f9d0aa693dabea5c585e266a90555 /sound/usb | |
| parent | 71d848ca00a16179b17e58e5f51c2d9a6c4f97a2 (diff) | |
[ALSA] usb-audio: schedule high speed URBs with 1 ms alignment
USB generic driver
The EHCI driver doesn't interrupt more than once per millisecond, and
organizes all iso transfers with frame-sized ITDs, so we can (try to)
be more efficient by aligning all URBs on frame boundaries.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Diffstat (limited to 'sound/usb')
| -rw-r--r-- | sound/usb/usbaudio.c | 20 |
1 files changed, 14 insertions, 6 deletions
diff --git a/sound/usb/usbaudio.c b/sound/usb/usbaudio.c index 49075f06f84..a62d1313da1 100644 --- a/sound/usb/usbaudio.c +++ b/sound/usb/usbaudio.c @@ -893,7 +893,7 @@ static int init_substream_urbs(snd_usb_substream_t *subs, unsigned int period_by { unsigned int maxsize, n, i; int is_playback = subs->direction == SNDRV_PCM_STREAM_PLAYBACK; - unsigned int npacks[MAX_URBS], urb_packs, total_packs; + unsigned int npacks[MAX_URBS], urb_packs, total_packs, packs_per_ms; /* calculate the frequency in 16.16 format */ if (snd_usb_get_speed(subs->dev) == USB_SPEED_FULL) @@ -920,14 +920,18 @@ static int init_substream_urbs(snd_usb_substream_t *subs, unsigned int period_by else subs->curpacksize = maxsize; + if (snd_usb_get_speed(subs->dev) == USB_SPEED_HIGH) + packs_per_ms = 8 >> subs->datainterval; + else + packs_per_ms = 1; + if (is_playback) { urb_packs = nrpacks; urb_packs = max(urb_packs, (unsigned int)MIN_PACKS_URB); urb_packs = min(urb_packs, (unsigned int)MAX_PACKS); } else urb_packs = 1; - if (snd_usb_get_speed(subs->dev) == USB_SPEED_HIGH) - urb_packs = (urb_packs * 8) >> subs->datainterval; + urb_packs *= packs_per_ms; /* allocate a temporary buffer for playback */ if (is_playback) { @@ -949,8 +953,12 @@ static int init_substream_urbs(snd_usb_substream_t *subs, unsigned int period_by minsize -= minsize >> 2; minsize = max(minsize, 1u); total_packs = (period_bytes + minsize - 1) / minsize; - if (total_packs < 2 * MIN_PACKS_URB) - total_packs = 2 * MIN_PACKS_URB; + /* round up to multiple of packs_per_ms */ + total_packs = (total_packs + packs_per_ms - 1) + & ~(packs_per_ms - 1); + /* we need at least two URBs for queueing */ + if (total_packs < 2 * MIN_PACKS_URB * packs_per_ms) + total_packs = 2 * MIN_PACKS_URB * packs_per_ms; } else { total_packs = MAX_URBS * urb_packs; } @@ -972,7 +980,7 @@ static int init_substream_urbs(snd_usb_substream_t *subs, unsigned int period_by subs->nurbs = 2; npacks[0] = (total_packs + 1) / 2; npacks[1] = total_packs - npacks[0]; - } else if (npacks[subs->nurbs-1] < MIN_PACKS_URB) { + } else if (npacks[subs->nurbs-1] < MIN_PACKS_URB * packs_per_ms) { /* the last packet is too small.. */ if (subs->nurbs > 2) { /* merge to the first one */ |