Messages in this thread | | | From | Jassi Brar <> | Date | Thu, 16 Feb 2023 22:04:17 -0600 | Subject | Re: [PATCH v1 0/7] MPFS system controller/mailbox fixes |
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On Thu, Feb 16, 2023 at 4:24 PM Conor Dooley <conor@kernel.org> wrote: > > > > > > Secondly, I have a question about what to do if a service does fail, but > > > > not due to a timeout - eg the above example where the "new" image for > > > > the FPGA is actually older than the one that currently exists. > > > > Ideally, if a service fails due to something other than the transaction > > > > timing out, I would go and read the status registers to see what the > > > > cause of failure was. > > > > I could not find a function in the mailbox framework that allows the > > > > client to request that sort of information from the client. Trying to > > > > do something with the auxiliary bus, or exporting some function to a > > > > device specific header seemed like a circumvention of the mailbox > > > > framework. > > > > Do you think it would be a good idea to implement something like > > > > mbox_client_peek_status(struct mbox_chan *chan, void *data) to allow > > > > clients to request this type of information? > > > > > > > .last_tx_done() is supposed to make sure everything is ok. > > > > Hm, might've explained badly as I think you've misunderstood. Or (see > > below) I might have mistakenly thought that last_tx_done() was only meant > > to signify that tx was done. > > > > Anyways, I'll try to clarify. > > Some services don't set a status, but whether a status is, or isn't, > > set has nothing to do with whether the service has completed. > > One service that sets a status is "Authenticate Bitstream". This > > service sets a status of 0x0 if the bitstream in question is okay _and_ > > something that the FPGA can be upgraded to. It returns a failure of 0x18 > > if the bitstream is valid _but_ is the same as that currently programmed. > > (and of course a whole host of other possible errors in-between) > > > > These statuses, and whether they are a bad outcome or not, is dependant > > on the service and I don't think should be handled in the mailbox > > controller driver. > > > > > If the expected status bit is "sometimes not set", that means that bit > > > is not the complete status. > > > > If the "busy" bit goes low, then the transmission must be complete, > > there should be no need to check other bits for *completion*, but... > > > > > You have to check multiple registers to > > > detect if and what caused the failure. > > > > ...maybe I have just misunderstood the role of .last_tx_done(). The > > comment in mailbox-controller.h lead me to believe that it was used just > > to check if it had been completed. > > > > Am I allowed to use .last_tx_done() to pass information back to the > > mailbox client? If I could, that'd certainly be a nice way to get the > > information on whether the service failed etc. > > > > Hopefully that, plus when you have a chance to look at the code, will > > make what I am asking about a little clearer! > > Just wondering if you've had a chance to look at this again! I know it's > missed the merge window this time around but I would like to get this > behaviour fixed as other work depends on it. > My opinion about adding a new api just to accommodate remote f/w's behaviour change across updates is still no. last_tx_done() is more abstract than you think -- it has to play with dozens of behaviors of remotes. So may just wrap your whatever logic, of "tx is done", in that.
This query within the patchset threw me off -- I thought you needed the new api for the patchset, so I didn't look further. Looking at it now, I am ok with applying Patches 1,2 and 3. If you want.
cheers.
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