Date:   Fri, 16 Dec 2016 18:59:04 +0100
From:   henrik@...tad.us
To:     linux-kernel@...r.kernel.org
Cc:     Richard Cochran <richardcochran@...il.com>, henrik@...tad.us,
        Henrik Austad <haustad@...co.com>, linux-media@...r.kernel.org,
        alsa-devel@...r.kernel.org, netdev@...r.kernel.org
Subject: [TSN RFC v2 0/9] TSN driver for the kernel

From: Henrik Austad <haustad@...co.com>


The driver is directed via ConfigFS as we need userspace to handle
stream-reservation (MSRP), discovery and enumeration (IEEE 1722.1) and
whatever other management is needed. This also includes running an
appropriate PTP daemon (TSN favors gPTP).

Once we have all the required attributes, we can create link using
mkdir, and use write() to set the attributes. Once ready, specify the
'shim' (basically a thin wrapper between TSN and another subsystem) and
we start pushing out frames.

The network part: it ties directly into the Rx-handler for receive and
writes skb's using dev_queue_xmit(). This could probably be improved.

2 new fields in netdev_ops have been introduced, and the Intel
igb-driver has been updated (as this an AVB-capable NIC which is
available as a PCI-e card).

What remains (tl;dr: a lot) a.k.a "Known problems" or "working on it!"
- tie to (g)PTP properly, currently using ktime_get() for presentation
  time
- get time from shim into TSN
- let shim create/manage buffer
- redo parts of the link-stuff using RCUs, the current setup is a bit
  clumsy.
- The igb-driver does not work properly when compiled with IGB_TSN, some
  details in setting the register values needs to be figured out. I am
  working on this, but as it stands, the best bet is to load tsn using
  in_debug=1 to bypass the capability-check. I have had e1000 and sky2
  running for several days without crashing, igb crashes and burns
  violently.
- The ALSA driver does not handle multiple devices very well and is a
  work in progress.

* v2: changes since v1

Changes since v1
- updated to latest upstream kernel (v4.8)
- set dedicated enabled-attribute and let shim be stored in own (support
  future plan for enabling per-shim attributes)
- fixed endianess issue in bitfields used in tsn-structs
- Updated some of the trace-events to use trace_class
- Fix various silly typos
- Handle disabling of link from hrtimer a bit more gracefully (that
  actually works-ish).
- use old skb and size of skb when that is set (Reporte by Nikita)
- Move PCP-codes to NIC and not in the link itself
- Allow TSN-capable card to be loaded even when in debug-mode (and do
  not enforce TSN behaviour)
- Start hooking into ALSA's get_time_info hooks (very much incomplete)
- use threads for sending frames, wake from hrtimer-callback.
  This also queues up awaiting timers if we fail to complete the
  transmit before another timer arrives, it will immediately execute
  another iteration, so no events should be lost. That being said,
  should this happen, it is a clear bug as we really should complete
  well before the next interval.
- Cleanup link-locking and differentiate between Talker and Listener (as
  Listener grab link-lock from IRQ context)
- Change list-lock to spinlock as we may need to take a link-lock whilst
  holding the master list-lock.
- Do a more careful dance holding the spinlocks to regions only doing
  actual update.

Network driver (I210 only)
- bring up all Tx-/Rx-queues when igb is in TSN-mode regardless of how
  many CPUs the system has for I210
- Correctly calculate the idle_slope in I210's configure hook
- Update igb-driver with queue-select and return correct queue when
  sending TSN-frames
- add IGB_FLAG_QAV_PRIO flag to igb_adapter (to handle proper config of
  tx-ring when adapter is brought up.
- add TXDCTL logic (part of preparatory work for TSN) to igb-driver
- Improve SR(A|B) accountingo

ALSA Shim
- Allow userspace to grab much smaller chunks of data (down to a single
  Class A frame for S16_LE 2ch 48kHz).
- Create the card with index/id pattern to avoid collision with other
  cards.
* v1

Before reading on - this is not even beta, but I'd really appreciate if
people would comment on the overall architecture and perhaps provide
some pointers to where I should improve/fix/update
- thanks!

This is a very early RFC for a TSN-driver in the kernel. It has been
floating around in my repo for a while and I would appreciate some
feedback on the overall design to avoid doing some major blunders.

There are at least one AVB-driver (the AV-part of TSN) in the kernel
already. This driver aims to solve a wider scope as TSN can do much more
than just audio. A very basic ALSA-driver is added to the end that
allows you to play music between 2 machines using aplay in one end and
arecord | aplay on the other (some fiddling required) We have plans for
doing the same for v4l2 eventually (but there are other fishes to fry
first). The same goes for a TSN_SOCK type approach as well.

Henrik Austad (9):
  igb: add missing fields to TXDCTL-register
  TSN: add documentation
  TSN: Add the standard formerly known as AVB to the kernel
  Adding TSN-driver to Intel I210 controller
  Add TSN header for the driver
  Add TSN machinery to drive the traffic from a shim over the network
  Add TSN event-tracing
  AVB ALSA - Add ALSA shim for TSN
  MAINTAINERS: add TSN/AVB-entries

 Documentation/TSN/tsn.txt                    |  345 ++++++++
 MAINTAINERS                                  |   14 +
 drivers/media/Kconfig                        |   15 +
 drivers/media/Makefile                       |    2 +-
 drivers/media/avb/Makefile                   |    5 +
 drivers/media/avb/avb_alsa.c                 |  793 +++++++++++++++++
 drivers/media/avb/tsn_iec61883.h             |  152 ++++
 drivers/net/ethernet/intel/Kconfig           |   18 +
 drivers/net/ethernet/intel/igb/Makefile      |    2 +-
 drivers/net/ethernet/intel/igb/e1000_82575.h |    4 +
 drivers/net/ethernet/intel/igb/igb.h         |   26 +
 drivers/net/ethernet/intel/igb/igb_main.c    |   39 +-
 drivers/net/ethernet/intel/igb/igb_tsn.c     |  468 ++++++++++
 include/linux/netdevice.h                    |   44 +
 include/linux/tsn.h                          |  952 +++++++++++++++++++++
 include/trace/events/tsn.h                   |  333 ++++++++
 net/Kconfig                                  |    1 +
 net/Makefile                                 |    1 +
 net/tsn/Kconfig                              |   32 +
 net/tsn/Makefile                             |    6 +
 net/tsn/tsn_configfs.c                       |  673 +++++++++++++++
 net/tsn/tsn_core.c                           | 1189 ++++++++++++++++++++++++++
 net/tsn/tsn_header.c                         |  162 ++++
 net/tsn/tsn_internal.h                       |  397 +++++++++
 net/tsn/tsn_net.c                            |  392 +++++++++
 25 files changed, 6061 insertions(+), 4 deletions(-)
 create mode 100644 Documentation/TSN/tsn.txt
 create mode 100644 drivers/media/avb/Makefile
 create mode 100644 drivers/media/avb/avb_alsa.c
 create mode 100644 drivers/media/avb/tsn_iec61883.h
 create mode 100644 drivers/net/ethernet/intel/igb/igb_tsn.c
 create mode 100644 include/linux/tsn.h
 create mode 100644 include/trace/events/tsn.h
 create mode 100644 net/tsn/Kconfig
 create mode 100644 net/tsn/Makefile
 create mode 100644 net/tsn/tsn_configfs.c
 create mode 100644 net/tsn/tsn_core.c
 create mode 100644 net/tsn/tsn_header.c
 create mode 100644 net/tsn/tsn_internal.h
 create mode 100644 net/tsn/tsn_net.c

--
2.7.4

Powered by blists - more mailing lists