From b263a9bdf9394062a4fc4272ebed60de331c5490 Mon Sep 17 00:00:00 2001 From: Clemens Ladisch Date: Mon, 15 Aug 2005 08:22:39 +0200 Subject: [PATCH] [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 --- sound/usb/usbaudio.c | 26 ++++++++------------------ 1 file 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; } -- 2.41.1