[alsa-devel] [PATCH] ALSA: firewire-lib/fireworks: fix miss detection of received MIDI messages

[Takashi Sakamoto]

Hi,

On Sat, Jun 29, 2019, at 00:44, Takashi Iwai wrote:
> On Fri, 28 Jun 2019 09:34:00 +0200,
> Takashi Sakamoto wrote:
> > 
> > Hi,
> > 
> > On Fri, Jun 28, 2019, at 17:53, Takashi Iwai wrote:
> > > On Fri, 28 Jun 2019 07:21:58 +0200,
> > > Takashi Sakamoto wrote:
> > > > 
> > > > In IEC 61883-6, 8 MIDI data streams are multiplexed into single
> > > > MIDI conformant data channel. The index of stream is calculated by
> > > > modulo 8 of the value of data block counter.
> > > > 
> > > > In fireworks, the value of data block counter in CIP header has a quirk
> > > > with firmware version v5.0.0, v5.7.3 and v5.8.0. This brings ALSA
> > > > IEC 61883-1/6 packet streaming engine to miss detection of MIDI
> > > > messages.
> > > > 
> > > > This commit fixes the miss detection to modify the value of data block
> > > > counter for the modulo calculation.
> > > > 
> > > > For maintainers, this bug exists since a commit 18f5ed365d3f ("ALSA:
> > > > fireworks/firewire-lib: add support for recent firmware quirk") in Linux
> > > > kernel v4.2. There're many changes since the commit.  This fix can be
> > > > backported to Linux kernel v4.4 or later. I tagged a base commit to the
> > > > backport for your convenience.
> > > > 
> > > > Fixes: df075feefbd3 ("ALSA: firewire-lib: complete AM824 data block processing layer")
> > > > Cc: <stable at vger.kernel.org> # v4.4+
> > > > Signed-off-by: Takashi Sakamoto <o-takashi at sakamocchi.jp>
> > > 
> > > This doesn't seem applicable to the latest 5.2-rc tree due to your
> > > recent refactoring.  Could you resubmit the fix for 5.2?  I'll resolve
> > > the merge conflict in my side.
> > 
> > Mmm. Do you actually encounter any conflict when applying this patch to
> > your v5.2 tree?
> > 
> > This patch includes changes for `sound/firewire/amdtp-am824.c`. On the other
> > hand, my recent work is mainly for `sound/firewire/amdtp-stream.c`. Actually,
> > the last change for `amdtp-am824.c` was done 2017-10-25.
> > https://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git/log/sound/firewire/amdtp-am824.c?h=for-linus
> 
> It's not about file conflicts but the compilation fails after the
> patch.
> sound/firewire/amdtp-am824.c: In function ‘read_midi_messages’:
> sound/firewire/amdtp-am824.c:324:16: error: ‘struct amdtp_stream’ has 
> no member named ‘ctx_data’
>    port = (8 - s->ctx_data.tx.first_dbc + s->data_block_counter + f) % 
> 8;
>                 ^~

Oops, now I got it... I just checked its application but should have had
compile test with old trees.

But I'm in short vacation. The revised patch will be posted next Monday,
sorry.


Thanks

Takashi Sakamoto