From mboxrd@z Thu Jan  1 00:00:00 1970
From: Clemens Ladisch <clemens@ladisch.de>
Subject: Re: [PATCH 2/3] fireface: add transaction support
Date: Tue, 8 Dec 2015 11:22:06 +0100
Message-ID: <5666AF4E.9000100@ladisch.de>
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To: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Cc: tiwai@suse.de, alsa-devel@alsa-project.org, ffado-devel@lists.sf.net
List-Id: alsa-devel@alsa-project.org

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.

> +		/* 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.


Regards,
Clemens