From 82755abfe872c9f2b9a108641f98d08435762dc4 Mon Sep 17 00:00:00 2001 From: Takashi Sakamoto Date: Thu, 21 Nov 2013 14:21:06 +0900 Subject: ALSA: firewire-lib: fix wrong value for FDF field as an empty packet This commit fix out of specification about the value of FDF field in out packet with 'no data'. This affects blocking mode. According to IEC 61883-6, there is two way to generate AMDTP packets include no data in blocking mode. Way 1. an empty packet defined in IEC 61883-1 - Size of packet is 2 quadlets. - The value of FDF is sfc. - The packet includes only CIP headers Way 2. a special non-empty packet defined in IEC 61883-6 - Size of packet is following to blocking mode - The value of FDF is 0xff. This value is 'NO-DATA'. This means 'The receiver' must ignore all the data in a CIP with this FDF code'. - The packet includes dummy data. But current implementation is a combination of them. - Size of packet is 2 (way 1) - FDF = 0xff (way 2) This causes BeBoB chipset cannot sound. This patch applies Way 1. Signed-off-by: Takashi Sakamoto Cc: Acked-by: Clemens Ladisch Signed-off-by: Takashi Iwai --- sound/firewire/amdtp.c | 15 ++++++--------- 1 file changed, 6 insertions(+), 9 deletions(-) --- a/sound/firewire/amdtp.c +++ b/sound/firewire/amdtp.c @@ -434,17 +434,14 @@ static void queue_out_packet(struct amdtp_out_stream *s, unsigned int cycle) return; index = s->packet_index; + /* this module generate empty packet for 'no data' */ syt = calculate_syt(s, cycle); - if (!(s->flags & CIP_BLOCKING)) { + if (!(s->flags & CIP_BLOCKING)) data_blocks = calculate_data_blocks(s); - } else { - if (syt != 0xffff) { - data_blocks = s->syt_interval; - } else { - data_blocks = 0; - syt = 0xffffff; - } - } + else if (syt != 0xffff) + data_blocks = s->syt_interval; + else + data_blocks = 0; buffer = s->buffer.packets[index].buffer; buffer[0] = cpu_to_be32(ACCESS_ONCE(s->source_node_id_field) |