diff options
| author | Takashi Sakamoto <o-takashi@sakamocchi.jp> | 2019-10-18 15:19:11 +0900 |
|---|---|---|
| committer | Takashi Iwai <tiwai@suse.de> | 2019-10-19 09:18:27 +0200 |
| commit | acfedcbe1ce4c69e1da914f39c02d945c80198d4 (patch) | |
| tree | 83adb14a072f8f13db5516c55f2b8c6458ce626c /sound/firewire/bebob | |
| parent | 60dd49298ec5803ca423836d5a724c3fe402cc3f (diff) | |
ALSA: firewire-lib: postpone to start IR context
Some devices have a quirk to postpone transmission of isoc packet for
several dozen or hundred isoc cycles since configured to transmit.
Furthermore, some devices have a quirk to transmit isoc packet with
discontinued data of its header.
In 1394 OHCI specification, software allows to start isoc context with
certain isoc cycle. Linux firewire subsystem has kernel API to use it
as well.
This commit uses the functionality of 1394 OHCI controller to handle
the quirks. At present, this feature is convenient to ALSA bebob and
fireface driver. As a result, some devices can be safely handled, as
long as I know:
- MAudio FireWire solo
- MAudio ProFire Lightbridge
- MAudio FireWire 410
- Roland FA-66
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Link: https://lore.kernel.org/r/20191018061911.24909-7-o-takashi@sakamocchi.jp
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound/firewire/bebob')
| -rw-r--r-- | sound/firewire/bebob/bebob_stream.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/sound/firewire/bebob/bebob_stream.c b/sound/firewire/bebob/bebob_stream.c index 5e4a61458be2..7ac0d9f495c4 100644 --- a/sound/firewire/bebob/bebob_stream.c +++ b/sound/firewire/bebob/bebob_stream.c @@ -658,7 +658,15 @@ int snd_bebob_stream_start_duplex(struct snd_bebob *bebob) if (err < 0) goto error; - err = amdtp_domain_start(&bebob->domain); + // The device postpones start of transmission mostly for 1 sec + // after receives packets firstly. For safe, IR context starts + // 1.5 sec (=12000 cycles) later. This is within 2.0 sec + // (=CALLBACK_TIMEOUT). + // Furthermore, some devices transfer isoc packets with + // discontinuous counter in the beginning of packet streaming. + // The delay has an effect to avoid detection of this + // discontinuity. + err = amdtp_domain_start(&bebob->domain, 12000); if (err < 0) goto error; |