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SubjectRe: [TSN RFC v2 0/9] TSN driver for the kernel
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On Fri, 2016-12-16 at 18:59 +0100, henrik@austad.us wrote:
> From: Henrik Austad <haustad@cisco.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).

I suggest using a generic netlink interface to communicate with the
driver to set up and/or configure your drivers.

I think configfs is frowned upon for network drivers. YMMV.

- Greg

>
> 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


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