From 245baf983cc39524cce39c24d01b276e6e653c9e Mon Sep 17 00:00:00 2001 From: Daniel Mack Date: Thu, 30 Aug 2012 18:52:30 +0200 Subject: [PATCH] ALSA: snd-usb: fix calls to next_packet_size In order to support devices with implicit feedback streaming models, packet sizes are now stored with each individual urb, and the PCM handling code which fills the buffers purely relies on the size fields now. However, calling snd_usb_audio_next_packet_size() for all possible packets in an URB at once, prior to letting the PCM code do its job does in fact not lead to the same behaviour than what the old code did: The PCM code will break its loop once a period boundary is reached, consequently using up less packets that it really could. As snd_usb_audio_next_packet_size() implements a feedback mechanism to the endpoints phase accumulator, the number of calls to that function matters, and when called too often, the data rate runs out of bounds. Fix this by making the next_packet function public, and call it from the PCM code as before if the packet data sizes are not defined. Signed-off-by: Daniel Mack Cc: stable@kernel.org [v3.5+] Signed-off-by: Takashi Iwai --- sound/usb/endpoint.c | 13 +------------ sound/usb/endpoint.h | 1 + sound/usb/pcm.c | 7 ++++++- 3 files changed, 8 insertions(+), 13 deletions(-) diff --git a/sound/usb/endpoint.c b/sound/usb/endpoint.c index b896c5559524..d6e2bb49c59c 100644 --- a/sound/usb/endpoint.c +++ b/sound/usb/endpoint.c @@ -141,7 +141,7 @@ int snd_usb_endpoint_implict_feedback_sink(struct snd_usb_endpoint *ep) * * For implicit feedback, next_packet_size() is unused. */ -static int next_packet_size(struct snd_usb_endpoint *ep) +int snd_usb_endpoint_next_packet_size(struct snd_usb_endpoint *ep) { unsigned long flags; int ret; @@ -177,15 +177,6 @@ static void retire_inbound_urb(struct snd_usb_endpoint *ep, ep->retire_data_urb(ep->data_subs, urb); } -static void prepare_outbound_urb_sizes(struct snd_usb_endpoint *ep, - struct snd_urb_ctx *ctx) -{ - int i; - - for (i = 0; i < ctx->packets; ++i) - ctx->packet_size[i] = next_packet_size(ep); -} - /* * Prepare a PLAYBACK urb for submission to the bus. */ @@ -370,7 +361,6 @@ static void snd_complete_urb(struct urb *urb) goto exit_clear; } - prepare_outbound_urb_sizes(ep, ctx); prepare_outbound_urb(ep, ctx); } else { retire_inbound_urb(ep, ctx); @@ -857,7 +847,6 @@ int snd_usb_endpoint_start(struct snd_usb_endpoint *ep, int can_sleep) goto __error; if (usb_pipeout(ep->pipe)) { - prepare_outbound_urb_sizes(ep, urb->context); prepare_outbound_urb(ep, urb->context); } else { prepare_inbound_urb(ep, urb->context); diff --git a/sound/usb/endpoint.h b/sound/usb/endpoint.h index a8e60c1408e5..cbbbdf226d66 100644 --- a/sound/usb/endpoint.h +++ b/sound/usb/endpoint.h @@ -21,6 +21,7 @@ int snd_usb_endpoint_deactivate(struct snd_usb_endpoint *ep); void snd_usb_endpoint_free(struct list_head *head); int snd_usb_endpoint_implict_feedback_sink(struct snd_usb_endpoint *ep); +int snd_usb_endpoint_next_packet_size(struct snd_usb_endpoint *ep); void snd_usb_handle_sync_urb(struct snd_usb_endpoint *ep, struct snd_usb_endpoint *sender, diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c index 5ceb8f1d63fb..e80b6687f43a 100644 --- a/sound/usb/pcm.c +++ b/sound/usb/pcm.c @@ -1029,6 +1029,7 @@ static void prepare_playback_urb(struct snd_usb_substream *subs, struct urb *urb) { struct snd_pcm_runtime *runtime = subs->pcm_substream->runtime; + struct snd_usb_endpoint *ep = subs->data_endpoint; struct snd_urb_ctx *ctx = urb->context; unsigned int counts, frames, bytes; int i, stride, period_elapsed = 0; @@ -1040,7 +1041,11 @@ static void prepare_playback_urb(struct snd_usb_substream *subs, urb->number_of_packets = 0; spin_lock_irqsave(&subs->lock, flags); for (i = 0; i < ctx->packets; i++) { - counts = ctx->packet_size[i]; + if (ctx->packet_size[i]) + counts = ctx->packet_size[i]; + else + counts = snd_usb_endpoint_next_packet_size(ep); + /* set up descriptor */ urb->iso_frame_desc[i].offset = frames * stride; urb->iso_frame_desc[i].length = counts * stride; -- 2.20.1