Messages in this thread | | | Date | Mon, 7 Jun 2021 19:27:54 +0100 | From | Sudeep Holla <> | Subject | Re: [RFC PATCH 01/10] firmware: arm_scmi: Reset properly xfer SCMI status |
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On Mon, Jun 07, 2021 at 07:01:37PM +0100, Cristian Marussi wrote: > On Mon, Jun 07, 2021 at 06:38:09PM +0100, Sudeep Holla wrote: > > On Sun, Jun 06, 2021 at 11:12:23PM +0100, Cristian Marussi wrote: > > > When an SCMI command transfer fails due to some protocol issue an SCMI > > > error code is reported inside the SCMI message payload itself and it is > > > then retrieved and transcribed by the specific transport layer into the > > > xfer.hdr.status field by transport specific .fetch_response(). > > > > > > The core SCMI transport layer never explicitly reset xfer.hdr.status, > > > so when an xfer is reused, if a transport misbehaved in handling such > > > status field, we risk to see an invalid ghost error code. > > > > > > Reset xfer.hdr.status to SCMI_SUCCESS right before each transfer is > > > started. > > > > > > > Any particular reason why it can't be part of xfer_get_init which has other > > initialisations ? If none, please move it there. > > > > Well it was there initially then I moved it here. > > The reason is mostly the same as the reason for the other patch in this > series that adds a reinit_completion() in this same point: the core does > not forbid to reuse an xfer multiple times, once obtained with xfer_get() > or xfer_get_init(), and indeed some protocols do such a thing: they > implements such do_xfer looping and bails out on error. >
Makes sense. But it is okay to retain xfer->transfer_id for every transfer in such a loop ?
> In the way that it is implemented now in protocols poses no problem > indeed because the do_xfer loop bails out on error and the xfer is put, > but as soon as some protocol is implemented that violates this common > practice and it just keeps on reuse an xfer after an error fo other > do_xfers() this breaks...so it seemed more defensive to just reinit the > completion and the status before each send.
Fair enough. But they use it to send same message I guess, may be if it gave error or something ? I would like to really know such a sequence instead of assisting that 😉.
-- Regards, Sudeep
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