[Skiboot] [PATCH v3 00/11] MBOX Protocol: Onwards to V3

[Stewart Smith]

Cyril Bur <cyril.bur at au1.ibm.com> writes:
> This is a respin of V2. The only real change I made is that we're
> using a compile time check to ensure that the handler arrays are big
> enough. This should catch mistakes when adding commands in the future.
> The merged v3 spec used different command numbers than I expected, so
> v2 did need a respin, I adjusted the constants.
>
> There are still caveats. There is currently no BMC v3 daemon. I have
> tested it against a proof of concept by Suraj but that is quite
> rudimentary testing at best.
>
> This series doesn't implement all of the V3 protocol. Skiboot doesn't
> actually need to implement all of the protocol. If it isn't going to
> use a command, it really doesn't need to have code for it. A future
> patch can implement the functionality if we decide we want/need it.
>
> V2 cover-letter below.
>
> Firstly, let me apologise for the amount of rework in this series.
> Ultimately the goal here was really the last three patches.
> Unfortunately in the process of writing them I started thinking about
> some of the problems in version 2.
>
> The easiest to address is a bug that came up in testing V3 which is
> that if opening a window fails, skiboot will assume that the previously
> opened window is still valid this is incorrect. Patch 2 address this
> problem.
>
> Then I got to thinking about errors and timeouts. It turns out that
> currently if mbox-flash decides a message times out, it will not be
> able to send anymore due to the lpc-mbox driver needing a response for
> every message it sent out - patch 4 deals with this. However after
> writing a significantly less invasive fix I realised that the entire
> handling of timeouts/retries/resends/late responses was racey. So a
> much simpler version of patch 4 became patches 3-6.
>
> Then there was some extra version 2 stuff that wasn't necessary but is
> nice to have - patch 7.
>
> Then on to actually implementing version 3 - at the time of writing
> version 2 Suraj did suggest what has become patch 8. This actually
> makes the version 3 patch - patch 9 very easy.
>
> The final patch is an extended, reworked and even more improved
> version of the tests I sent with version 2 (which weren't merged at
> the time)
>
> One final note: this series passes all the tests I can throw at it
> however I do not have reliable access to a MBOX version 3 Daemon
> running on real hardware. Suraj has been kind enough to use (very)
> similar versions of this series in his testing and he informs me that
> there are no problems, however this exact code has never run on real
> hardware.
>
> Cyril Bur (11):
>   libflash/mbox-flash: Add v2 error codes
>   libflash/mbox-flash: Always close windows before opening a new window
>   libflash/mbox-flash: Move sequence handling to driver level
>   libflash/mbox-flash: Allow mbox-flash to tell the driver msg timeouts
>   hw/lpc-mbox: Simplify message bookkeeping and timeouts
>   libflash/mbox-flash: Simplify message sending
>   libflash/mbox-flash: Use BMC suggested timeout value
>   libflash/mbox-flash: Use static arrays of function pointers
>   libflash/mbox-flash: Understand v3
>   libflash/mbox-flash: Add the ability to lock flash
>   libflash/test: Add tests for mbox-flash

thanks, series merged to master as of
b9774c47eecd0c90e503919432ec1e4a86355398.

Even though we don't really have a v3 mbox daemon, the testing is
valuable and this should be a place to start from and is probably "good
enough" without shooting ourselves in the foot too hard when v3 mbox
daemons start appearing.

-- 
Stewart Smith
OPAL Architect, IBM.