Hey Jassi, On Sat, Jan 21, 2023 at 07:12:52PM +0000, Conor Dooley wrote: > On Sat, Jan 21, 2023 at 10:01:41AM -0600, Jassi Brar wrote: > > On Wed, Jan 11, 2023 at 7:45 AM Conor Dooley wrote: > > > > > > In order to differentiate between the service succeeding & the system > > > controller being inoperative or otherwise unable to function, I had to > > > switch the controller to poll a busy bit in the system controller's > > > registers to see if it has completed a service. > > > This makes sense anyway, as the interrupt corresponds to "data ready" > > > rather than "tx done", so I have changed the mailbox controller driver > > > to do that & left the interrupt solely for signalling data ready. > > > It just so happened that all of the services that I had worked with and > > > tested up to this point were "infallible" & did not set a status, so the > > > particular code paths were never tested. > > > > > > Jassi, the mailbox and soc patches depend on each other, as the change > > > in what the interrupt is used for requires changing the client driver's > > > behaviour too, as mbox_send_message() will now return when the system > > > controller is no longer busy rather than when the data is ready. > > > I'm happy to send the lot via the soc tree with your Ack and/or reivew, > > > if that also works you? > > > > > Ok, let me review them and get back to you. > > FYI, I did sent a v2 on Friday: > https://lore.kernel.org/all/20230120143734.3438755-1-conor.dooley@microchip.com/ > > The change is just a timeout duration though. > > > > 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. Thanks, Conor.