Re: [PATCH v1 00/10] baseband/acc200

[Thomas Monjalon <thomas@monjalon.net>]

31/08/2022 18:43, Maxime Coquelin:
> Hello Nicolas,
> 
> On 8/30/22 21:45, Chautru, Nicolas wrote:
> > Hi Maxime,
> > 
> >> -----Original Message-----
> >> From: Maxime Coquelin <maxime.coquelin@redhat.com>
> >> Sent: Tuesday, August 30, 2022 12:45 AM
> >> To: Chautru, Nicolas <nicolas.chautru@intel.com>; dev@dpdk.org;
> >> thomas@monjalon.net; gakhil@marvell.com; hemant.agrawal@nxp.com;
> >> trix@redhat.com; Vargas, Hernan <hernan.vargas@intel.com>
> >> Cc: mdr@ashroe.eu; Richardson, Bruce <bruce.richardson@intel.com>;
> >> david.marchand@redhat.com; stephen@networkplumber.org
> >> Subject: Re: [PATCH v1 00/10] baseband/acc200
> >>
> >> Hi Nicolas,
> >>
> >> On 7/12/22 15:48, Maxime Coquelin wrote:
> >>> Hi Nicolas, Hernan,
> >>>
> >>> (Adding Hernan in the recipients list)
> >>>
> >>> On 7/8/22 02:01, Nicolas Chautru wrote:
> >>>> This is targeting 22.11 and includes the PMD for the integrated
> >>>> accelerator on Intel Xeon SPR-EEC.
> >>>> There is a dependency on that parallel serie still in-flight which
> >>>> extends the bbdev api
> >>>> https://patches.dpdk.org/project/dpdk/list/?series=23894
> >>>>
> >>>> I will be offline for a few weeks for the summer break but Hernan
> >>>> will cover for me during that time if required.
> >>>>
> >>>> Thanks
> >>>> Nic
> >>>>
> >>>> Nicolas Chautru (10):
> >>>>     baseband/acc200: introduce PMD for ACC200
> >>>>     baseband/acc200: add HW register definitions
> >>>>     baseband/acc200: add info get function
> >>>>     baseband/acc200: add queue configuration
> >>>>     baseband/acc200: add LDPC processing functions
> >>>>     baseband/acc200: add LTE processing functions
> >>>>     baseband/acc200: add support for FFT operations
> >>>>     baseband/acc200: support interrupt
> >>>>     baseband/acc200: add device status and vf2pf comms
> >>>>     baseband/acc200: add PF configure companion function
> >>>>
> >>>>    MAINTAINERS                              |    3 +
> >>>>    app/test-bbdev/meson.build               |    3 +
> >>>>    app/test-bbdev/test_bbdev_perf.c         |   76 +
> >>>>    doc/guides/bbdevs/acc200.rst             |  244 ++
> >>>>    doc/guides/bbdevs/index.rst              |    1 +
> >>>>    drivers/baseband/acc200/acc200_pf_enum.h |  468 +++
> >>>>    drivers/baseband/acc200/acc200_pmd.h     |  690 ++++
> >>>>    drivers/baseband/acc200/acc200_vf_enum.h |   89 +
> >>>>    drivers/baseband/acc200/meson.build      |    8 +
> >>>>    drivers/baseband/acc200/rte_acc200_cfg.h |  115 +
> >>>>    drivers/baseband/acc200/rte_acc200_pmd.c | 5403
> >>>> ++++++++++++++++++++++++++++++
> >>>>    drivers/baseband/acc200/version.map      |   10 +
> >>>>    drivers/baseband/meson.build             |    1 +
> >>>>    13 files changed, 7111 insertions(+)
> >>>>    create mode 100644 doc/guides/bbdevs/acc200.rst
> >>>>    create mode 100644 drivers/baseband/acc200/acc200_pf_enum.h
> >>>>    create mode 100644 drivers/baseband/acc200/acc200_pmd.h
> >>>>    create mode 100644 drivers/baseband/acc200/acc200_vf_enum.h
> >>>>    create mode 100644 drivers/baseband/acc200/meson.build
> >>>>    create mode 100644 drivers/baseband/acc200/rte_acc200_cfg.h
> >>>>    create mode 100644 drivers/baseband/acc200/rte_acc200_pmd.c
> >>>>    create mode 100644 drivers/baseband/acc200/version.map
> >>>>
> >>>
> >>> Comparing ACC200 & ACC100 header files, I understand ACC200 is an
> >>> evolution of the ACC10x family. The FEC bits are really close, ACC200
> >>> main addition seems to be FFT acceleration which could be handled in
> >>> ACC10x driver based on device ID.
> >>>
> >>> I think both drivers have to be merged in order to avoid code
> >>> duplication. That's how other families of devices (e.g. i40e) are
> >>> handled.
> >>
> >> I haven't seen your reply on this point.
> >> Do you confirm you are working on a single driver for ACC family in order to
> >> avoid code duplication?
> >>
> > 
> > The implementation is based on distinct ACC100 and ACC200 drivers. The 2 devices are fundamentally different generation, processes and IP.
> > MountBryce is an eASIC device over PCIe while ACC200 is an integrated accelerator on Xeon CPU.
> 
> The underlying technology does not matter much. For example we use same
> Virtio driver for SW emulated devices and fully HW offloaded ones.
> 
> I have spent some time today comparing the drivers and what I can see is
> the ACC200 driver is a copy-paste of the ACC100, modulo FFT addition and
> other small changes that I think could be handled dynamically based on
> capabilities flags and device ID.
> 
> > The actual implementation are not the same, underlying IP are all distinct even if many of the descriptor format have similarities.
> > The actual capabilities of the acceleration are different and/or new.
> 
> New capabilities should be backed by device capabilities flags.
> 
> > The workaround and silicon errata are also different causing different limitation and implementation in the driver (see the serie with ongoing changes for ACC100 in parallel).
> > This is fundamentally distinct from ACC101 which was a derivative product from ACC100 and where it made sense to share implementation between ACC100 and ACC101.
> > So in a nutshell these 2 devices and drivers are 2 different beasts and the intention is to keep them intentionally separate as in the serie.
> > Let me know if unclear, thanks!
> 
> Thanks for the information.
> I still think it should be a single driver, I would appreciate a second
> opinion. Thomas, Bruce, Stephen, do you have time to have a look?

If most code is similar, it should be the same driver.