Re: [alsa-devel] [PATCH 1/3] ALSA: bebob: expand sleep just after breaking connections for protocol version 1

[Steve Morris <morris@buinea.com>]

On Fri, Nov 01, 2019 at 10:13:21PM +0900, Takashi Sakamoto wrote:
> As long as I investigated, some devices with BeBoB protocol version 1
> can be freezed during several hundreds milliseconds after breaking
> connections. When accessing during the freezed time, any transaction
> is corrupted. In the worst case, the device is going to reboot.
> 
> I can see this issue in:
>  * Roland FA-66
>  * M-Audio FireWire Solo
> 
> This commit expands sleep just after breaking connections to avoid
> the freezed time as much as possible. I note that the freeze/reboot
> behaviour is similar to below models:
>  * Focusrite Saffire Pro 10 I/O
>  * Focusrite Saffire Pro 26 I/O
> 
> The above models certainly reboot after breaking connections.
> 
> Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
> ---
>  sound/firewire/bebob/bebob_stream.c | 11 ++++++-----
>  1 file changed, 6 insertions(+), 5 deletions(-)
> 
> diff --git a/sound/firewire/bebob/bebob_stream.c b/sound/firewire/bebob/bebob_stream.c
> index f7f0db5aa811..1b264d0d63eb 100644
> --- a/sound/firewire/bebob/bebob_stream.c
> +++ b/sound/firewire/bebob/bebob_stream.c
> @@ -415,15 +415,16 @@ static int make_both_connections(struct snd_bebob *bebob)
>  	return 0;
>  }
>  
> -static void
> -break_both_connections(struct snd_bebob *bebob)
> +static void break_both_connections(struct snd_bebob *bebob)
>  {
>  	cmp_connection_break(&bebob->in_conn);
>  	cmp_connection_break(&bebob->out_conn);
>  
> -	/* These models seems to be in transition state for a longer time. */
> -	if (bebob->maudio_special_quirk != NULL)
> -		msleep(200);
> +	// These models seem to be in transition state for a longer time. When
> +	// accessing in the state, any transactions is corrupted. In the worst
> +	// case, the device is going to reboot.
> +	if (bebob->version < 2)
> +		msleep(600);
>  }
>  
>  static int
> -- 
> 2.20.1
> 
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This patch causes a reboot when I power on my Edirol FA-101. This is
consistent behavior with kernels 5.5.1 - 5.5.11.

I've changed msleep(600) back to msleep(200) and rebuilt the module and
I am once again able to power on and use the interface.

I am running Arch linux with 5.5.11-arch1-1 #1 SMP PREEMPT Sun, 22 Mar 2020 16:33:15 +0000 x86_64 GNU/Linux.


I had previously posted to the list on Feb 19, 2020 with the subject:

sytem reboots when initializing Edirol FA-101 firewire audio interface

Please forgive any lapses in reporting protocol as I generally don't
work at the kernel level. Hopefully this more specific report will help
fix the issue.

Thanks, 

Steve