On Mon, 2018-09-17 at 23:36 +0900, Takashi Sakamoto wrote:
Hi,
I prepare branches in two remote repositories:
https://github.com/takaswie/snd-firewire-improve/tree/topic/tascam-userspace
(a384019c0f78)
(a5994ec2165f)
Installing the patched driver, you can read the status and control message in userspace by mmap(2).
Patched libhinawa produces HinawaSndTscm GObject class. This class is also available with gobject introspection. For example with PyGobject:
#/usr/bin/env python3 from time import sleep import gi gi.require_version('Hinawa', '2.0') from gi.repository import Hinawa unit = Hinawa.SndTscm() # I assume card number 1 is assigned. Take care of file permission. unit.open('/dev/snd/hwC1D0') unit.listen() while (True): for i, frame in enumerate(unit.get_status()): print('{0:02d}: {1:08x}'.format(i, frame)) sleep(0.1)This code print the message to stdout, but not start packet streaming. You need to start it by ALSA PCM/rawMIDI interfaces, like: $ aplay -Dplughw:1,0 /dev/urandom
I notice that the branches include patches I introduced[1], with some minor optimizations to Linux kernel v4.17 or later. The patches are written just to satisfy investigation work and really ad-hoc ones.
Thanks! I finally had some time to try it out.
My test system is running a 4.12 kernel from openSUSE Leap 15.0. I backported the patches but had to remove your GFP_KERNEL patch for it to work on my kernel. With the GFP_KERNEL patch, user space was not seeing updates to the data stream. With it removed, I had a constant update.
The kernel was unstable and the system hard locked frequently with the patches enabled (with and without the GFP_KERNEL patch). But I was able to map out all the controller functions to the bits in the first 16 quadlets. I will write up my findings and send them later.
I noticed that we are able to control the LEDs from the host via the asynchronous link. Do you you think the faders are also controlled that way or would that also go via isochronous packets to the FW-1884?
The rx isochronous packets from system to the unit include no data to control the unit[2]. If the faders are movable from system software, it should be achieved by asynchronous transactions, like blighting LEDs.
I guess without an analyzer that will be difficult to track down.
-Scott