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    SubjectRe: [PATCH v7 00/38] SCMI vendor protocols and modularization
    On Thu, Mar 25, 2021 at 09:09:52PM -0700, Florian Fainelli wrote:
    >
    >
    > On 3/16/2021 5:48 AM, Cristian Marussi wrote:
    > > Hi all,
    > >
    > > The current SCMI implementation does not provide an interface to easily
    > > develop and include a custom vendor protocol implementation as prescribed
    > > by the SCMI standard, also because, there is not currently any custom
    > > protocol in the upstream to justify the development of a custom interface
    > > and its maintenance.
    > >
    > > Moreover the current interface exposes protocol operations to the SCMI
    > > driver users attaching per-protocol operations directly to the handle
    > > structure, which, in this way, tends to grow indefinitely for each new
    > > protocol addition.
    > >
    > > Beside this, protocols private data are also exposed via handle *_priv
    > > pointers, making such private data accessible also to the SCMI drivers
    > > even if neither really needed nor advisable.
    > >
    > > This series wants to address this by simplifying the SCMI protocols
    > > interface and reducing it, roughly, to these common generic operations:
    > >
    > > - handle->devm_protocol_get()
    > > - handle->devm_protocol_put()
    > > - handle->notify_ops->*
    > >
    > > All protocols' private data pointers are removed from handle too and made
    > > accessible only to the protocols code through dedicated internal helpers.
    > >
    > > The concept of protocol handle is also introduced in the SCMI protocol code
    > > to represent a protocol instance initialized against a specific SCMI
    > > instance (handle), so that all the new protocol code uses such protocol
    > > handles wherever previously SCMI handle was used: this enable tighter
    > > control of what is exposed to the protocol code vs the SCMI drivers.
    > >
    > > Moreover protocol initialization is moved away from device probe and now
    > > happens on demand when the first user shows up (first .protocol_get), while
    > > de-initialization is performed once the last user of the protocol, even in
    > > terms of registered notifications callback, is gone, with the SCMI core
    > > taking care to perform all the needed underlying resource accounting.
    > >
    > > This way any new future standard or custom protocol implementation will
    > > expose a common unified interface which does not need to be extended
    > > endlessly: no need to maintain a custom interface only for vendor protos.
    > > SCMI drivers written on top of standard or custom protocols will use this
    > > same common interface to access any protocol operations.
    > >
    > > All existent upstream SCMI drivers are converted to this new interface.
    > >
    > > In order to make this migration painless and to avoid the need of a big
    > > un-mergeable jumbo patch touching all over the protocols and drivers (like
    > > it was in v2), since v3 the migration process has been heavily split with a
    > > bit of transient code added along the way (to preserve bisectability) and
    > > finally removed towards the ends of the series.
    > > Protocols and SCMI drivers migration to the new interface happens along
    > > patches 10->30.
    > >
    > > Leveraging this new centralized and common initialization flow we took
    > > care also to refactor and simplify protocol-events registration and remove
    > > *notify_priv from the handle interface making it accessible only to the
    > > notification core.
    > >
    > > Patch 37 builds on top of this new interface and introduces a mechanism to
    > > define an SCMI protocol as a full blown module (possibly loadable) while
    > > leaving the core dealing with proper resource accounting.
    > > Standard protocols are still kept as builtins in this series, though.
    > >
    > > Finally, patch 38 introduces dynamic SCMI devices creation to avoid having
    > > to update the static module device table in the core each time a new driver
    > > is added.
    > >
    > > The whole SCMI stack can still be built alternatively as a module, with all
    > > the standard protocols included in scmi-module.ko in such a case.
    > >
    > > On top of this series an example SCMI Custom protocol 0x99 and related
    > > SCMI Custom Dummy driver has been built and it is available at [1] as a
    > > series of DEBUG patches on top this same series.
    > >
    > > The series is currently based on sudeep/for-next/scmi [2] on top of:
    > >
    > > commit 908a4f778dc7 ("Merge branch 'ib-iio-scmi-5.12-rc2-take3' of
    > > git://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio into
    > > for-next/scmi")
    > >
    > > Any feedback welcome.
    >
    > You copied me on each round and thanks for doing that, I did not have
    > time to go look at each change, but sensors, clocks and cpufreq still
    > worked on ARCH_BRCMSTB with both 32-bit and 64-bit kernels, so:
    >
    > Tested-by: Florian Fainelli <f.fainelli@gmail.com>
    >
    Great, thanks for taking time to test this !

    And btw, thanks for your initial feedback anyway, it spawned a lot of
    needed rework across this series.

    Thanks

    Cristian
    > Thanks!
    > --
    > Florian

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