ALSA: fireface: start IR context immediately

In the latter models of RME Fireface series, device start to transfer
packets several dozens of milliseconds. On the other hand, ALSA fireface
driver starts IR context 2 milliseconds after the start. This results
in loss to handle incoming packets on the context.

This commit changes to start IR context immediately instead of
postponement. For Fireface 800, this affects nothing because the device
transfer packets 100 milliseconds or so after the start and this is
within wait timeout.

Cc: <stable@vger.kernel.org>
Fixes: acfedcbe1ce4 ("ALSA: firewire-lib: postpone to start IR context")
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Link: https://lore.kernel.org/r/20200510074301.116224-3-o-takashi@sakamocchi.jp
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/firewire/fireface/ff-stream.c b/sound/firewire/fireface/ff-stream.c
index 63b79c4..5452115 100644 (file)
--- a/sound/firewire/fireface/ff-stream.c
+++ b/sound/firewire/fireface/ff-stream.c
@@ -184,7 +184,6 @@ 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)
@@ -200,14 +199,7 @@ int snd_ff_stream_start_duplex(struct snd_ff *ff, unsigned int rate)
                if (err < 0)
                        goto error;
 
-               // 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);
+               err = amdtp_domain_start(&ff->domain, 0);
                if (err < 0)
                        goto error;