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authorTakashi Sakamoto <o-takashi@sakamocchi.jp>2017-06-07 09:38:05 +0900
committerTakashi Iwai <tiwai@suse.de>2017-06-07 07:53:32 +0200
commit875becf8412c60ffae93c5f69e95a4d023f0e8ee (patch)
tree04baa851c60f7c068d8b8218aeea20947cd40ba7 /sound/firewire/oxfw
parentf7a478178a8ea970abd34f7ab73e66c9119b1606 (diff)
downloadlinux-875becf8412c60ffae93c5f69e95a4d023f0e8ee.tar.bz2
ALSA: firewire: process packets in 'struct snd_pcm_ops.ack' callback
In recent commit for ALSA PCM core, some arrangement is done for 'struct snd_pcm_ops.ack' callback. This is called when appl_ptr is explicitly moved in intermediate buffer for PCM frames, except for some cases described later. For drivers in ALSA firewire stack, usage of this callback has a merit to reduce latency between time of PCM frame queueing and handling actual packets in recent isochronous cycle, because no need to wait for software IRQ context from isochronous context of OHCI 1394. If this works well in a case that mapped page frame is used for the intermediate buffer, user process should execute some commands for ioctl(2) to tell the number of handled PCM frames in the intermediate buffer just after handling them. Therefore, at present, with a combination of below conditions, this doesn't work as expected and user process should wait for the software IRQ context as usual: - when ALSA PCM core judges page frame mapping is available for status data (struct snd_pcm_mmap_status) and control data (struct snd_pcm_mmap_control). - user process handles PCM frames by loop just with 'snd_pcm_mmap_begin()' and 'snd_pcm_mmap_commit()'. - user process uses PCM hw plugin in alsa-lib to operate I/O without 'sync_ptr_ioctl' option. Unfortunately, major use case include these three conditions. Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp> Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound/firewire/oxfw')
-rw-r--r--sound/firewire/oxfw/oxfw-pcm.c16
1 files changed, 16 insertions, 0 deletions
diff --git a/sound/firewire/oxfw/oxfw-pcm.c b/sound/firewire/oxfw/oxfw-pcm.c
index d4594f7115ae..bc1a3a36ab06 100644
--- a/sound/firewire/oxfw/oxfw-pcm.c
+++ b/sound/firewire/oxfw/oxfw-pcm.c
@@ -382,6 +382,20 @@ static snd_pcm_uframes_t pcm_playback_pointer(struct snd_pcm_substream *sbstm)
return amdtp_stream_pcm_pointer(&oxfw->rx_stream);
}
+static int pcm_capture_ack(struct snd_pcm_substream *substream)
+{
+ struct snd_oxfw *oxfw = substream->private_data;
+
+ return amdtp_stream_pcm_ack(&oxfw->tx_stream);
+}
+
+static int pcm_playback_ack(struct snd_pcm_substream *substream)
+{
+ struct snd_oxfw *oxfw = substream->private_data;
+
+ return amdtp_stream_pcm_ack(&oxfw->rx_stream);
+}
+
int snd_oxfw_create_pcm(struct snd_oxfw *oxfw)
{
static const struct snd_pcm_ops capture_ops = {
@@ -393,6 +407,7 @@ int snd_oxfw_create_pcm(struct snd_oxfw *oxfw)
.prepare = pcm_capture_prepare,
.trigger = pcm_capture_trigger,
.pointer = pcm_capture_pointer,
+ .ack = pcm_capture_ack,
.page = snd_pcm_lib_get_vmalloc_page,
.mmap = snd_pcm_lib_mmap_vmalloc,
};
@@ -405,6 +420,7 @@ int snd_oxfw_create_pcm(struct snd_oxfw *oxfw)
.prepare = pcm_playback_prepare,
.trigger = pcm_playback_trigger,
.pointer = pcm_playback_pointer,
+ .ack = pcm_playback_ack,
.page = snd_pcm_lib_get_vmalloc_page,
.mmap = snd_pcm_lib_mmap_vmalloc,
};