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From: Stefan Richter <stefanr@s5r6.in-berlin.de>
To: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Cc: tiwai@suse.de, alsa-devel@alsa-project.org, clemens@ladisch.de,
	ffado-devel@lists.sf.net
Subject: Re: [PATCH 18/39] firewire-lib: Add a fallback at RCODE_CANCELLED
Date: Fri, 28 Feb 2014 21:25:35 +0100
Message-ID: <20140228212535.7606e0d8@stein> (raw)
In-Reply-To: <1393558072-25926-19-git-send-email-o-takashi@sakamocchi.jp>

On Feb 28 Takashi Sakamoto wrote:
> Linux Firewire Subsystem currently gives
> 200msec for default timeout (See DEFAULT_SPLIT_TIMEOUT in core-card.c).

It's 2000 ms actually.

And this is the IEEE 1394 split transaction timeout of course.  FCP
transactions on the other hand are transported by means of two IEEE 1394
transactions:  One in which the FCP requester is IEEE 1394 requester, and
another one in which the FCP responder is IEEE 1394 requester.

firewire-core's split transaction timeout is only relevant to the request
subaction of an FCP transaction (i.e. the first one of the two IEEE 1394
transaction), and only if this one is being performed as a split
transaction rather than a unified transaction, which depends on the FCP
responder hardware.  (I am not aware of any hardware which handles
FCP request subactions as unified transactions.)

IEC 61883-1 does not specify any FCP transaction timeout.

The 1394 TA document "AV/C Digital Interface Command Set, Rev. 1.0,
1996" defines FCP transactions (for use with AV/C command set) much more
precisely than IEC 61883-1 does:

  - To each FCP request, there may be 0..n FCP responses.

  - An AV/C target may emit a final response (one with response code <
    0xf) up to 100 ms after reception of an FCP request.

  - Or the AV/C target may emit an intermediate response (one with
    response code 0xf for interim response) up to 100 ms after reception
    of an FCP request.  The target shall emit no additional interim
    response in this transaction, but one final response.  There is no
    timeout specified for this final-after-interim response, i.e. it may
    take an undefined, possibly very long time.  (The AV/C
    specification v4.0, 2001 adds that subunit specifications may define
    such timeouts for certain commands.)

  - Or the AV/C target may still be busy processing a previous command.
    In this case, the specification accepts that the target does not send
    any response to subsequent requests at all until it is done with the
    previous work.  The requester may the retry such a failed request after
    the mentioned 100 ms timeout.  (Plus IEEE 1394 transport overhead, but
    the AV/C specification v1.0 does not mention this.  AV/C v4.0 explains
    that the requester should take certain transport dependent delays
    into account in addition to the 100 ms FCP timeout, e.g. physical layer
    repeater delays, or busy retry delays.  Furthermore, AV/C v4.0
    recommends that a busy target returns certain acknowledge codes or
    response codes to pipelined requests that exceed its capacity
    to handle concurrent FCP transactions.)

  - An "IEEE 1394.0 reset" (sic) terminates any outstanding FCP transaction.
    (I suppose a 1394 bus reset is meant by this.  AV/C v4.0 clarifies this
    to be an IEEE 1394 bus reset indeed.)

>From a quick glance, the FCP transaction specification looks unchanged
from AV/C 4.0, 2001 to v4.1, 2001 and to v4.2, 2004.
-- 
Stefan Richter
-=====-====- --=- ===--
http://arcgraph.de/sr/

  reply index

Thread overview: 69+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-02-28  3:27 [GIT PULL][PATCH 00/39] Enhancement of support for Firewire devices Takashi Sakamoto
2014-02-28  3:27 ` [PATCH 01/39] firewire-lib: Rename functions, structure, member for AMDTP Takashi Sakamoto
2014-02-28  3:27 ` [PATCH 02/39] firewire-lib: Add macros instead of fixed value " Takashi Sakamoto
2014-02-28  3:27 ` [PATCH 03/39] firewire-lib: Add 'direction' member to 'amdtp_stream' structure Takashi Sakamoto
2014-02-28  3:27 ` [PATCH 04/39] firewire-lib: Split some codes into functions to reuse for both streams Takashi Sakamoto
2014-02-28  3:27 ` [PATCH 05/39] firewire-lib: Add support for AMDTP in-stream and PCM capture Takashi Sakamoto
2014-02-28  3:27 ` [PATCH 06/39] firewire-lib: Add support for MIDI capture/playback Takashi Sakamoto
2014-02-28  3:27 ` [PATCH 07/39] firewire-lib: Give syt value as parameter to handle_out_packet() Takashi Sakamoto
2014-02-28  3:27 ` [PATCH 08/39] firewire-lib: Add support for duplex streams synchronization in blocking mode Takashi Sakamoto
2014-02-28  3:27 ` [PATCH 09/39] firewire-lib: Add sort function for transmitted packet Takashi Sakamoto
2014-02-28  6:40   ` Takashi Iwai
2014-02-28 14:31     ` Takashi Sakamoto
2014-02-28  3:27 ` [PATCH 10/39] firewire-lib: Add transfer delay to synchronized duplex streams Takashi Sakamoto
2014-02-28  3:27 ` [PATCH 11/39] firewire-lib: Add support for channel mapping Takashi Sakamoto
2014-02-28  3:27 ` [PATCH 12/39] firewire-lib: Rename macros, variables and functions for CMP Takashi Sakamoto
2014-02-28  3:27 ` [PATCH 13/39] firewire-lib: Add 'direction' member to 'cmp_connection' structure Takashi Sakamoto
2014-02-28  3:27 ` [PATCH 14/39] firewire-lib: Add handling output connection by CMP Takashi Sakamoto
2014-02-28  3:27 ` [PATCH 15/39] firewire-lib: Add a new function to check others' connection Takashi Sakamoto
2014-02-28  3:27 ` [PATCH 16/39] firewire-lib: Add some AV/C general commands Takashi Sakamoto
2014-02-28  3:27 ` [PATCH 17/39] firewire-lib: Add quirks for Fireworks Takashi Sakamoto
2014-02-28  3:27 ` [PATCH 18/39] firewire-lib: Add a fallback at RCODE_CANCELLED Takashi Sakamoto
2014-02-28 20:25   ` Stefan Richter [this message]
2014-02-28 20:39     ` Stefan Richter
2014-03-01  3:18     ` Takashi Sakamoto
2014-03-01 10:10       ` Stefan Richter
2014-03-01 12:22         ` Takashi Sakamoto
2014-03-01 14:20           ` Stefan Richter
2014-03-04  1:35             ` [FFADO-devel] " Jonathan Woithe
2014-03-04  8:33               ` Stefan Richter
2014-03-04  9:28                 ` Stefan Richter
2014-03-01 10:34   ` Stefan Richter
2014-03-01 12:23     ` Takashi Sakamoto
2014-02-28  3:27 ` [PATCH 19/39] fireworks: Add skelton for Fireworks based devices Takashi Sakamoto
2014-02-28  6:51   ` Takashi Iwai
2014-02-28 15:05     ` Takashi Sakamoto
2014-02-28 15:10       ` Takashi Iwai
2014-02-28 15:36         ` Takashi Sakamoto
2014-02-28  3:27 ` [PATCH 20/39] fireworks: Add transaction and some commands Takashi Sakamoto
2014-02-28  3:27 ` [PATCH 21/39] fireworks: Add connection and stream management Takashi Sakamoto
2014-02-28  3:27 ` [PATCH 22/39] fireworks: Add proc interface for debugging purpose Takashi Sakamoto
2014-02-28  6:54   ` Takashi Iwai
2014-03-01 13:17     ` Takashi Sakamoto
2014-03-03  9:01       ` Takashi Iwai
2014-03-04 14:10         ` Takashi Sakamoto
2014-02-28  3:27 ` [PATCH 23/39] fireworks: Add MIDI interface Takashi Sakamoto
2014-02-28  3:27 ` [PATCH 24/39] fireworks: Add PCM interface Takashi Sakamoto
2014-02-28  3:27 ` [PATCH 25/39] fireworks: Add hwdep interface Takashi Sakamoto
2014-02-28  3:27 ` [PATCH 26/39] fireworks: Add command/response functionality into " Takashi Sakamoto
2014-02-28  6:58   ` Takashi Iwai
2014-03-01 13:18     ` Takashi Sakamoto
2014-02-28  3:27 ` [PATCH 27/39] bebob: Add skelton for BeBoB based devices Takashi Sakamoto
2014-02-28  3:27 ` [PATCH 28/39] bebob: Add commands and connections/streams management Takashi Sakamoto
2014-02-28  3:27 ` [PATCH 29/39] bebob: Add proc interface for debugging purpose Takashi Sakamoto
2014-02-28  3:27 ` [PATCH 30/39] bebob: Add MIDI interface Takashi Sakamoto
2014-02-28  3:27 ` [PATCH 31/39] bebob: Add PCM interface Takashi Sakamoto
2014-02-28  3:27 ` [PATCH 32/39] bebob: Add hwdep interface Takashi Sakamoto
2014-02-28  3:27 ` [PATCH 33/39] bebob: Prepare for device specific operations Takashi Sakamoto
2014-02-28  3:27 ` [PATCH 34/39] bebob: Add support for Terratec PHASE, EWS series and Aureon Takashi Sakamoto
2014-02-28  3:27 ` [PATCH 35/39] bebob: Add support for Yamaha GO series Takashi Sakamoto
2014-02-28  3:27 ` [PATCH 36/39] bebob: Add support for Focusrite Saffire/SaffirePro series Takashi Sakamoto
2014-02-28  3:27 ` [PATCH 37/39] bebob: Add support for M-Audio usual Firewire series Takashi Sakamoto
2014-02-28  3:27 ` [PATCH 38/39] bebob: Send a cue to load firmware for M-Audio " Takashi Sakamoto
2014-02-28  3:27 ` [PATCH 39/39] bebob: Add support for M-Audio special " Takashi Sakamoto
2014-03-01 10:53   ` Stefan Richter
2014-03-01 13:06     ` Takashi Sakamoto
2014-03-01 14:32       ` Stefan Richter
2014-02-28  6:36 ` [GIT PULL][PATCH 00/39] Enhancement of support for Firewire devices Takashi Iwai
2014-03-01 13:14   ` Takashi Sakamoto
     [not found] <5316963F.1000206@sakamocchi.jp>
2014-03-05 10:47 ` [GIT PULL][PATCH 00/39 v2] " Takashi Sakamoto
2014-03-05 10:48   ` [PATCH 18/39] firewire-lib: Add a fallback at RCODE_CANCELLED Takashi Sakamoto

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