RE: [PATCH v2 00/16] Switchtec NTB Support

["Allen Hubbe" <Allen.Hubbe@dell.com>]

From: Logan Gunthorpe
> Changes since v1:
>=20
> - Rebased onto latest ntb-next branch (with v4.13-rc1)
> - Reworked ntb_mw_count() function so that it can be called all the
>   time (per discussion with Allen)
> - Various spelling and formatting cleanups from Bjorn
> - Added request_module() call such that the NTB module is =
automatically
>   loaded when appropriate hardware exists.

Patches 5..16:

Acked-by: Allen Hubbe <Allen.Hubbe@dell.com>

Should the order of 6 and 7 be swapped?



While I still have some objections to this series, we have already been =
over them, and I won't let these stand in the way:

6 - I think just the comment is best.  Rather than prohibit the use of =
functionality for hardware that does support the calls, in my opinion it =
should be left to specific hardware drivers to return an error.

14 - I would prefer that a non-hardware-supported implementation of =
spads via a memory window should be common code, not reinvented in each =
specific hardware driver that lacks hardware spads.  You pointed out =
that the spads implemented here use the shared_mw construct, which is =
specific to this driver.  I am concerned that spads in the shared_mw =
(really anything in shared_mw, including this driver's indication of the =
peer link state) limits the applicability of this driver to just =
configurations of two ntb ports.  You stated this limitation upfront.

>=20
> --
>=20
> Changes since the rfc:
>=20
> - Rebased on ntb-next
> - Switched ntb_part_op to use sleep instead of delay
> - Dropped a number of useless dbg __func__ prints
> - Went back to the dynamic instead of the static class
> - Swapped the notifier block for a simple callback
> - Modified the new ntb api so that a couple functions with pidx
>   now must be called after link up. Per our discussion on the list.
>=20
> --
>=20
> This patchset implements Non-Transparent Bridge (NTB) support for the
> Microsemi Switchtec series of switches. We're looking for some
> review from the community at this point but hope to get it upstreamed
> for v4.14.
>=20
> Switchtec NTB support is configured over the same function and bar
> as the management endpoint. Thus, the new driver hooks into the
> management driver which we had merged in v4.12. We use the class
> interface API to register an NTB device for every switchtec device
> which supports NTB (not all do).
>=20
> The Switchtec hardware supports doorbells, memory windows and =
messages.
> Seeing there is no native scratchpad support, 128 spads are emulated
> through the use of a pre-setup memory window. The switch has 64
> doorbells which are shared between the two partitions and a
> configurable set of memory windows. While the hardware supports more
> than 2 partitions, this driver only supports the first two seeing
> the current NTB API only supports two hosts.
>=20
> The driver has been tested with ntb_netdev and fully passes the
> ntb_test script.
>=20
> This patchset is based off of ntb-next and can be found in this
> git repo:
>=20
> https://github.com/sbates130272/linux-p2pmem.git switchtec_ntb_v2
>=20
> Logan Gunthorpe (16):
>   switchtec: move structure definitions into a common header
>   switchtec: export class symbol for use in upper layer driver
>   switchtec: add NTB hardware register definitions
>   switchtec: add link event notifier callback
>   ntb: ensure ntb_mw_get_align() is only called when the link is up
>   ntb: add check and comment for link up to mw_count() and
>     mw_get_align()
>   ntb: ntb_test: ensure the link is up before trying to configure the
>     mws
>   switchtec_ntb: introduce initial NTB driver
>   switchtec_ntb: initialize hardware for memory windows
>   switchtec_ntb: initialize hardware for doorbells and messages
>   switchtec_ntb: add skeleton NTB driver
>   switchtec_ntb: add link management
>   switchtec_ntb: implement doorbell registers
>   switchtec_ntb: implement scratchpad registers
>   switchtec_ntb: add memory window support
>   switchtec_ntb: update switchtec documentation with notes for NTB
>=20
>  Documentation/switchtec.txt             |   12 +
>  MAINTAINERS                             |    2 +
>  drivers/ntb/hw/Kconfig                  |    1 +
>  drivers/ntb/hw/Makefile                 |    1 +
>  drivers/ntb/hw/mscc/Kconfig             |    9 +
>  drivers/ntb/hw/mscc/Makefile            |    1 +
>  drivers/ntb/hw/mscc/switchtec_ntb.c     | 1213 =
+++++++++++++++++++++++++++++++
>  drivers/ntb/ntb_transport.c             |   20 +-
>  drivers/ntb/test/ntb_perf.c             |   18 +-
>  drivers/ntb/test/ntb_tool.c             |    6 +-
>  drivers/pci/switch/switchtec.c          |  316 ++------
>  include/linux/ntb.h                     |   11 +-
>  include/linux/switchtec.h               |  373 ++++++++++
>  tools/testing/selftests/ntb/ntb_test.sh |    4 +
>  14 files changed, 1704 insertions(+), 283 deletions(-)
>  create mode 100644 drivers/ntb/hw/mscc/Kconfig
>  create mode 100644 drivers/ntb/hw/mscc/Makefile
>  create mode 100644 drivers/ntb/hw/mscc/switchtec_ntb.c
>  create mode 100644 include/linux/switchtec.h
>=20
> --
> 2.11.0