linux-kernel - Re: [PATCH 0/4] firewire: core: handle TASCAM FW-1884/FW-1804/FW-1082 quirk

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Message-ID: <20251020001926.GA52936@workstation.local>
Date: Mon, 20 Oct 2025 09:19:26 +0900
From: Takashi Sakamoto <o-takashi@...amocchi.jp>
To: linux1394-devel@...ts.sourceforge.net
Cc: linux-kernel@...r.kernel.org, linux-sound@...r.kernel.org
Subject: Re: [PATCH 0/4] firewire: core: handle TASCAM
 FW-1884/FW-1804/FW-1082 quirk

On Sat, Oct 18, 2025 at 12:55:28PM +0900, Takashi Sakamoto wrote:
> Hi,
> 
> In 2003, TEAC Corporation had released FW-1884/FW-1804/FW-1082 in its
> TASCAM brand. These devices are already supported by a driver in ALSA
> firewire stack, but they have an interoperability issue related to
> the speed of asynchronous transactions and isochronous transmissions.
> When operating at the speed described in configuration ROM, they are
> too lazy to respond, and eventually frozen.
> 
> The most likely cause of this issue is a mismatch in the gap count
> between the initiators and receivers. Theoretically, this can be
> resolved by transmitting phy configuration packets to optimize gap count.
> Nevertheless, this approach has proven ineffective, suggesting that the
> device firmware may contain a bug causing the issue.
> 
> From my experience, these devices operate more reliably at lower
> transaction and transmission speeds, which provides a practical
> mitigation.
> 
> This patch series addresses the interoperability issue. The core function
> of Linux FireWire subsystem is changed to read the entire configuration
> ROM at the lowest speed (S100), and to identify these devices based on its
> contents. Once identified, their maximum speed is limited to S200. The
> ALSA driver then performs asynchronous requests and isochronous
> transmission at that speed to prevent device freezes.
> 
> Takashi Sakamoto (4):
>   firewire: core: code refactoring to compute transaction speed
>   firewire: core: determine transaction speed after detecting quirks
>   firewire: core: handle device quirk of TASCAM FW-1884/FW-1804/FW-1082
>   ALSA: firewire-tascam: reserve resources for transferred isochronous
>     packets at S400
> 
>  drivers/firewire/core-device.c        | 86 +++++++++++++++------------
>  include/linux/firewire.h              |  3 +
>  sound/firewire/tascam/tascam-stream.c | 21 +++----
>  3 files changed, 63 insertions(+), 47 deletions(-)
> 
> 
> base-commit: 15f9610fc96ac6fd2844e63f7bf5a0b08e1c31c8

Applied to for-next branch.

To sound subsystem maintainer, I'll send the 4th patch to mainline as a
part of firewire subsystem updates in next merge window.


Regards

Takashi Sakamoto
`