Messages in this thread |  | | Date | Sat, 21 Jan 2023 19:12:52 +0000 | From | Conor Dooley <> | Subject | Re: [PATCH v1 0/7] MPFS system controller/mailbox fixes |
| |
On Sat, Jan 21, 2023 at 10:01:41AM -0600, Jassi Brar wrote: > On Wed, Jan 11, 2023 at 7:45 AM Conor Dooley <conor.dooley@microchip.com> 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!
Thanks, Conor. [unhandled content-type:application/pgp-signature] |  |