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

[Takashi Iwai <tiwai@suse.de>]

On Thu, 26 Mar 2020 22:47:22 +0100,
Steve Morris wrote:
> 
> 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
> > 
> > _______________________________________________
> > Alsa-devel mailing list
> > Alsa-devel@alsa-project.org
> > https://mailman.alsa-project.org/mailman/listinfo/alsa-devel
> 
> 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.

This is weird.  If just changing the msleep value from 600 to 200
"fixes" the problem, it means that something is already fundamentally
broken...


Takashi