In ALSA firewire stack, 8 drivers uses IEC 61883-1/6 engine for data
transmission. They have common PCM info/constraints and duplicated codes.
This commit unifies the codes into fireiwre-lib.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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>
This commit adds hwdep interface so as the other sound drivers for units
on IEEE 1394 bus have.
This interface is designed for mixer/control applications. By using this
interface, an application can get information about firewire node, can
lock/unlock kernel streaming and can get notification at starting/stopping
kernel streaming.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit adds PCM functionality to transmit/receive PCM samples.
When one of PCM substreams are running or external clock source is
selected, current sampling rate is used. Else, the sampling rate is
changed according to requests from a userspace application.
Available number of samples in a frame of PCM substream is determined at
open(2) to corresponding PCM character device. Later, packet streaming
starts by ioctl(2) with SNDRV_PCM_IOCTL_PREPARE. In theory, between them,
applications can change state of the unit by any write transaction to
change the number. In this case, this driver may fail packet streaming due
to wrong data format.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Takashi Sakamoto