On Thu, 2017-09-07 at 18:26 -0700, Guenter Roeck wrote: > On 09/07/2017 06:02 PM, Andrew Jeffery wrote: > > On Thu, 2017-09-07 at 17:27 -0700, Guenter Roeck wrote: > > > On 09/07/2017 08:22 AM, Andrew Jeffery wrote: > > > > On Thu, 2017-09-07 at 06:40 -0700, Guenter Roeck wrote: > > > > > On 09/06/2017 04:32 PM, Andrew Jeffery wrote: > > > > > > > > > > > > > > > > > > > Guess I need to dig up my eval board and see if I can reproduce the problem. > > > > > > > Seems you are saying that the problem is always seen when issuing a sequence > > > > > > > of "clear faults" commands on multiple pages ? > > > > > > > > > > > > Yeah. We're also seeing bad behaviour under other command sequences as well, > > > > > > which lead to this hack of a work-around patch[1]. > > > > > > > > > > > > I'd be very interested in the results of testing against the eval board. I > > > > > > don't have access to one and it seems Maxim have discontinued them. > > > > > > > > > > > > > > > > Do you have a somewhat reliable means to reproduce the problem ? > > > > > > > > It seems we hit a bunch of problems by just continually > > > > binding/unbinding the driver, if you don't apply that hacky oneshot > > > > retry patch. We can hit problems (in our design?) with something like: > > > > > > > > # cd /sys/bus/i2c/drivers/max31785; \ > > > > echo $addr > unbind; \ > > > > while echo $addr > bind; \ > > > > do echo $addr > unbind; echo -n .; done; > > > > > > > > It should hit issues covered by this patch, as the register checks are > > > > used in the operations used by probe. > > > > > > > > > > Hmm ... I didn't use your driver but my prototype driver which also supports > > > temperature and voltage attributes, so if anything it should create more > > > stress on the chip. > > > > I did add the temp and voltage attributes... > > > > Any chance you can give mine a try? I don't know what I would have done > > to invoke this kind of behaviour, so it would be useful to know whether > > or not it happens with one driver but not the other. > > > > Will do. Thanks. For reference, here's a devicetree description: https://github.com/openbmc/linux/blob/dev-4.10/arch/arm/boot/dts/aspeed-bmc-opp-witherspoon.dts#L283 > > > > No error so far, after running the script for a couple > > > of minutes. How long does it take for errors to appear, and how do I see > > > that there is an error ? > > > > I'm seeing failures after anything from a handful of bind/unbinds, to > > hundreds of bind/unbinds. It seems to vary. > > > > > Does the driver fail to instantiate ? > > > > Typically probe fails so the loop exits. It usually gets -EIO and the > > shell spits out "No such device". > > > > Thanks for testing, it's a useful data point for us hunting down the > > source of our problems. > > > > I aborted the test after ~2,500 loops without error. Yeah, I'd consider that fairly stable. Cheers, Andrew
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