Re: [alsa-devel] [PATCH 05/39] firewire-lib: Add support for AMDTP in-stream and PCM capture

Takashi Sakamoto wrote:

For capturing PCM, this commit adds the functionality to handle in-stream. This is also applied for dual-wire mode.

+++ b/sound/firewire/amdtp.c @@ -200,16 +208,26 @@ void amdtp_stream_set_pcm_format(struct amdtp_stream *s,

• if (s->direction == AMDTP_OUT_STREAM) {
  

• 	if (s->dual_wire)
  

• 		s->transfer_samples = amdtp_write_s32_dualwire;
  

• 	else
  

• 		s->transfer_samples = amdtp_write_s32;
  

• } else if (s->dual_wire) {
  

• 	s->transfer_samples = amdtp_read_s32_dualwire;
  

• } else {
  

• 	s->transfer_samples = amdtp_read_s32;
  

• }
  

Please format the if/else branches in the same way.

+static void handle_in_packet(struct amdtp_stream *s, ...

• /* ignore empty CIP packet or NO-DATA AMDTP packet */
• if ((payload_quadlets < 3) ||

•    (((cip_header[1] & CIP_FDF_MASK) >> CIP_FDF_SFC_SHIFT) ==
  

• 					AMDTP_FDF_NO_DATA))
  

(AMDTP_FDF_NO_DATA << CIP_FDF_SFC_SHIFT) would be a constant that could be computed at compile time.

• /* check packet continuity */
• s->data_block_counter = (s->data_block_counter + data_blocks) & 0xff;
• if (s->data_block_counter != data_block_counter) {

• dev_info_ratelimited(&s->unit->device,
  

• 		     "Detect uncontinuity of CIP packets\n");
  

• s->data_block_counter = data_block_counter;
  

• return;
  

In practice, this error means that a packet was dropped. I guess this doesn't actually happen too often, but eventually, we should handle this either by inserting some samples or by stopping the stream.

Regards, Clemens