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ALSA: firewire-lib: postpone to start IR context

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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>
This commit is contained in:
Takashi Sakamoto
2019-10-18 15:19:11 +09:00
committed by Takashi Iwai
parent 60dd49298e
commit acfedcbe1c
10 changed files with 98 additions and 15 deletions
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sound/firewire/fireface/ff-stream.c
+9 -1
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@@ -184,6 +184,7 @@ int snd_ff_stream_start_duplex(struct snd_ff *ff, unsigned int rate)
*/
if (!amdtp_stream_running(&ff->rx_stream)) {
int spd = fw_parent_device(ff->unit)->max_speed;
unsigned int ir_delay_cycle;
err = ff->spec->protocol->begin_session(ff, rate);
if (err < 0)
@@ -199,7 +200,14 @@ int snd_ff_stream_start_duplex(struct snd_ff *ff, unsigned int rate)
if (err < 0)
goto error;
err = amdtp_domain_start(&ff->domain);
// The device postpones start of transmission mostly for several
// cycles after receiving packets firstly.
if (ff->spec->protocol == &snd_ff_protocol_ff800)
ir_delay_cycle = 800; // = 100 msec
else
ir_delay_cycle = 16; // = 2 msec
err = amdtp_domain_start(&ff->domain, ir_delay_cycle);
if (err < 0)
goto error;