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authorClemens Ladisch <clemens@ladisch.de>2005-08-15 08:22:39 +0200
committerJaroslav Kysela <perex@suse.cz>2005-08-30 08:45:41 +0200
commitb263a9bdf9394062a4fc4272ebed60de331c5490 (patch)
tree440f459eb1cd93ed015c38bf20e93e122d4a32e0 /sound
parent99250872fc619bb5b5ddddcf1c58714a774526fc (diff)
[ALSA] usb-audio: optimize handling of capture URBs
USB generic driver When preparing capture URBs, we don't need to stop when we cross a period boundary because we now never handle more than one millisecond of data per URB anyway. When handling captured data, use an extra flag to call snd_pcm_period_elapsed() no more than once. This allows us to move the period boundary checking code before the copying of the data which avoids a second locking of the substream's lock. Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Diffstat (limited to 'sound')
-rw-r--r--sound/usb/usbaudio.c26
1 files changed, 8 insertions, 18 deletions
diff --git a/sound/usb/usbaudio.c b/sound/usb/usbaudio.c
index a62d1313da1..a703d96bfcb 100644
--- a/sound/usb/usbaudio.c
+++ b/sound/usb/usbaudio.c
@@ -311,27 +311,18 @@ static int prepare_capture_urb(snd_usb_substream_t *subs,
struct urb *urb)
{
int i, offs;
- unsigned long flags;
snd_urb_ctx_t *ctx = (snd_urb_ctx_t *)urb->context;
offs = 0;
urb->dev = ctx->subs->dev; /* we need to set this at each time */
- urb->number_of_packets = 0;
- spin_lock_irqsave(&subs->lock, flags);
for (i = 0; i < ctx->packets; i++) {
urb->iso_frame_desc[i].offset = offs;
urb->iso_frame_desc[i].length = subs->curpacksize;
offs += subs->curpacksize;
- urb->number_of_packets++;
- subs->transfer_sched += subs->curframesize;
- if (subs->transfer_sched >= runtime->period_size) {
- subs->transfer_sched -= runtime->period_size;
- break;
- }
}
- spin_unlock_irqrestore(&subs->lock, flags);
urb->transfer_buffer = ctx->buf;
urb->transfer_buffer_length = offs;
+ urb->number_of_packets = ctx->packets;
#if 0 // for check
if (! urb->bandwidth) {
int bustime;
@@ -359,6 +350,7 @@ static int retire_capture_urb(snd_usb_substream_t *subs,
unsigned char *cp;
int i;
unsigned int stride, len, oldptr;
+ int period_elapsed = 0;
stride = runtime->frame_bits >> 3;
@@ -378,6 +370,10 @@ static int retire_capture_urb(snd_usb_substream_t *subs,
if (subs->hwptr_done >= runtime->buffer_size)
subs->hwptr_done -= runtime->buffer_size;
subs->transfer_done += len;
+ if (subs->transfer_done >= runtime->period_size) {
+ subs->transfer_done -= runtime->period_size;
+ period_elapsed = 1;
+ }
spin_unlock_irqrestore(&subs->lock, flags);
/* copy a data chunk */
if (oldptr + len > runtime->buffer_size) {
@@ -388,15 +384,9 @@ static int retire_capture_urb(snd_usb_substream_t *subs,
} else {
memcpy(runtime->dma_area + oldptr * stride, cp, len * stride);
}
- /* update the pointer, call callback if necessary */
- spin_lock_irqsave(&subs->lock, flags);
- if (subs->transfer_done >= runtime->period_size) {
- subs->transfer_done -= runtime->period_size;
- spin_unlock_irqrestore(&subs->lock, flags);
- snd_pcm_period_elapsed(subs->pcm_substream);
- } else
- spin_unlock_irqrestore(&subs->lock, flags);
}
+ if (period_elapsed)
+ snd_pcm_period_elapsed(subs->pcm_substream);
return 0;
}