netdev - Re: [PATCH net-next RFC 00/13] Add devlink reload level option

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Message-ID: <CAACQVJo+bAr_k=LjgdTKbOxFEkpbYAsaWbkSDjUepgO7_XQfNA@mail.gmail.com>
Date:   Mon, 3 Aug 2020 15:54:59 +0530
From:   Vasundhara Volam <vasundhara-v.volam@...adcom.com>
To:     Jacob Keller <jacob.e.keller@...el.com>
Cc:     Moshe Shemesh <moshe@...lanox.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jiri Pirko <jiri@...lanox.com>,
        Netdev <netdev@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net-next RFC 00/13] Add devlink reload level option

On Tue, Jul 28, 2020 at 10:13 PM Jacob Keller <jacob.e.keller@...el.com> wrote:
>
>
>
> On 7/27/2020 10:25 PM, Vasundhara Volam wrote:
> > On Mon, Jul 27, 2020 at 4:36 PM Moshe Shemesh <moshe@...lanox.com> wrote:
> >>
> >> Introduce new option on devlink reload API to enable the user to select the
> >> reload level required. Complete support for all levels in mlx5.
> >> The following reload levels are supported:
> >>   driver: Driver entities re-instantiation only.
> >>   fw_reset: Firmware reset and driver entities re-instantiation.
> > The Name is a little confusing. I think it should be renamed to
> > fw_live_reset (in which both firmware and driver entities are
> > re-instantiated).  For only fw_reset, the driver should not undergo
> > reset (it requires a driver reload for firmware to undergo reset).
> >
>
> So, I think the differentiation here is that "live_patch" doesn't reset
> anything.
This seems similar to flashing the firmware and does not reset anything.

>
> >>   fw_live_patch: Firmware live patching only.
> > This level is not clear. Is this similar to flashing??
> >
> > Also I have a basic query. The reload command is split into
> > reload_up/reload_down handlers (Please correct me if this behaviour is
> > changed with this patchset). What if the vendor specific driver does
> > not support up/down and needs only a single handler to fire a firmware
> > reset or firmware live reset command?
>
> In the "reload_down" handler, they would trigger the appropriate reset,
> and quiesce anything that needs to be done. Then on reload up, it would
> restore and bring up anything quiesced in the first stage.
Yes, I got the "reload_down" and "reload_up". Similar to the device
"remove" and "re-probe" respectively.

But our requirement is a similar "ethtool reset" command, where
ethtool calls a single callback in driver and driver just sends a
firmware command for doing the reset. Once firmware receives the
command, it will initiate the reset of driver and firmware entities
asynchronously.