[alsa-devel] [PATCH 2/3] fireface: add transaction support

[Takashi Sakamoto]

On Dec 08 2015 19:22, Clemens Ladisch wrote:
> Takashi Sakamoto wrote:
>> +static void transmit_midi_msg(struct snd_ff *ff, unsigned int port)
>> ...
>> +	/* Retrieve one MIDI byte to calculate length of the message. */
>> +	len = snd_rawmidi_transmit_peek(substream, buf,
>> +					SND_FF_MAXIMIM_MIDI_QUADS);
> 
> SND_FF_MAXIMIM_MIDI_QUADS does not have the value 1.

Oops. It's my mistake to left the message as what it had been.
Originally, I programmed to retrieve one byte. Later, I investigated the
maximum message size and changed the code.

>> +		/* Calculate consume bytes. */
>> +		consume = calculate_message_bytes(status);
>> +		if (consume <= 0)
>> +			return;
> 
> As far as I can see, sending one of the "undefined" bytes can stop the
> stream permanently.  Invalid bytes need to be acked to ignore/remove
> them.

Exactly. We should find better way to handle such messages. Do you have
any good ideas?


Thanks

Takashi Sakamoto