Messages in this thread | | | Date | Mon, 23 Oct 2023 09:48:53 +0200 | From | Miquel Raynal <> | Subject | Re: [PATCH v2 Resent 6/6] i3c: master: svc: fix random hot join failure since timeout errory |
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Hi Frank,
Frank.li@nxp.com wrote on Fri, 20 Oct 2023 15:58:25 -0400:
> On Fri, Oct 20, 2023 at 07:03:37PM +0200, Miquel Raynal wrote: > > Hi Frank, > > > > Frank.li@nxp.com wrote on Fri, 20 Oct 2023 11:47:48 -0400: > > > > > On Fri, Oct 20, 2023 at 05:20:06PM +0200, Miquel Raynal wrote: > > > > Hi Frank, > > > > > > > > Frank.li@nxp.com wrote on Fri, 20 Oct 2023 10:47:52 -0400: > > > > > > > > > On Fri, Oct 20, 2023 at 04:35:25PM +0200, Miquel Raynal wrote: > > > > > > Hi Frank, > > > > > > > > > > > > Frank.li@nxp.com wrote on Fri, 20 Oct 2023 10:18:55 -0400: > > > > > > > > > > > > > On Fri, Oct 20, 2023 at 04:06:45PM +0200, Miquel Raynal wrote: > > > > > > > > Hi Frank, > > > > > > > > > > > > > > > > Frank.li@nxp.com wrote on Thu, 19 Oct 2023 11:39:42 -0400: > > > > > > > > > > > > > > > > > On Thu, Oct 19, 2023 at 08:44:52AM +0200, Miquel Raynal wrote: > > > > > > > > > > Hi Frank, > > > > > > > > > > > > > > > > > > > > Frank.Li@nxp.com wrote on Wed, 18 Oct 2023 11:59:26 -0400: > > > > > > > > > > > > > > > > > > > > > master side report: > > > > > > > > > > > silvaco-i3c-master 44330000.i3c-master: Error condition: MSTATUS 0x020090c7, MERRWARN 0x00100000 > > > > > > > > > > > > > > > > > > > > > > BIT 20: TIMEOUT error > > > > > > > > > > > The module has stalled too long in a frame. This happens when: > > > > > > > > > > > - The TX FIFO or RX FIFO is not handled and the bus is stuck in the > > > > > > > > > > > middle of a message, > > > > > > > > > > > - No STOP was issued and between messages, > > > > > > > > > > > - IBI manual is used and no decision was made. > > > > > > > > > > > > > > > > > > > > I am still not convinced this should be ignored in all cases. > > > > > > > > > > > > > > > > > > > > Case 1 is a problem because the hardware failed somehow. > > > > > > > > > > > > > > > > > > But so far, no action to handle this case in current code. > > > > > > > > > > > > > > > > Yes, but if you detect an issue and ignore it, it's not better than > > > > > > > > reporting it without handling it. Instead of totally ignoring this I > > > > > > > > would at least write a debug message (identical to what's below) before > > > > > > > > returning false, even though I am not convinced unconditionally > > > > > > > > returning false here is wise. If you fail a hardware sequence because > > > > > > > > you added a printk, it's a problem. Maybe you consider this line as > > > > > > > > noise, but I believe it's still an error condition. Maybe, however, > > > > > > > > this bit gets set after the whole sequence, and this is just a "bus > > > > > > > > is idle" condition. If that's the case, then you need some > > > > > > > > additional heuristics to properly ignore the bit? > > > > > > > > > > > > > > > > > > > > > > dev_err(master->dev, > > > > > > > "Error condition: MSTATUS 0x%08x, MERRWARN 0x%08x\n", > > > > > > > mstatus, merrwarn); > > > > > > > + > > > > > > > + /* ignore timeout error */ > > > > > > > + if (merrwarn & SVC_I3C_MERRWARN_TIMEOUT) > > > > > > > + return false; > > > > > > > + > > > > > > > > > > > > > > Is it okay move SVC_I3C_MERRWARN_TIMEOUT after dev_err? > > > > > > > > > > > > I think you mentioned earlier that the problem was not the printk but > > > > > > the return value. So perhaps there is a way to know if the timeout > > > > > > happened after a transaction and was legitimate or not? > > > > > > > > > > Error message just annoise user, don't impact function. But return false > > > > > let IBI thread running to avoid dead lock. > > > > > > > > > > > > > > > > > In any case we should probably lower the log level for this error. > > > > > > > > > > Only SVC_I3C_MERRWARN_TIMEOUT is warning > > > > > > > > > > Maybe below logic is better > > > > > > > > > > if (merrwarn & SVC_I3C_MERRWARN_TIMEOUT) { > > > > > dev_dbg(master->dev, > > > > > "Error condition: MSTATUS 0x%08x, MERRWARN 0x%08x\n", > > > > > mstatus, merrwarn); > > > > > return false; > > > > > } > > > > > > > > > > dev_err(master->dev, > > > > > "Error condition: MSTATUS 0x%08x, MERRWARN 0x%08x\n", > > > > > mstatus, merrwarn); > > > > > .... > > > > > > > > > > > > > Yes, this looks better but I wonder if we should add an additional > > > > condition to just return false in this case; > > > > > > What's additional condition we can check? > > > > Well, you're the one bothered with an error case which is not a real > > error. You're saying "this error is never a problem" and I am saying > > that I believe it is not a problem is your particular case, but in > > general there might be situations where it *is* a problem. So you need > > to find proper conditions to check against in order to determine > > whether this is just an info with no consequence or an error. > > I checked R** code of this TIMEOUT, which is quite simple, set to 1 if SDA > is low over 100us if I understand correctly. I also checked, if I add delay > before emit stop, TIMEOUT will be set. (Read can auto emit stop accoring to > RDTERM, so just saw TIMEOUT at write transaction). > > TIMEOUT just means condition "I3C bus's SDA low over 100us" happened since > written 1 to TIMEOUT. > > I think "I3C bus's SDA over 100us" means nothing for linux drivers. > > I think there are NO sitation where it *is* a problem. If it was problem, > there are NO solution to resolve it at linux driver side. And I think it > already happen many times silencely.
Ok then, I'll opt for your last proposal of printing the error message at the debug loglevel and return false.
Thanks, Miquèl
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