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    SubjectRe: [PATCH] hwmon: pmbus: Make reg check and clear faults functions return errors
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    On Thu, 2017-09-07 at 19:17 -0700, Guenter Roeck wrote:
    > On 09/07/2017 07:06 PM, Andrew Jeffery wrote:
    > > 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
    > >
    >
    > I can't test with devicetree. x86 system.
    >
    > 2,100+ iterations with your driver, no failures.

    Great. I really appreciate your testing here, so thanks for your
    efforts. I owe you a few drinks if we ever happen to meet.

    >
    > Either it is because my chip is a MAX31785 (not A), or the configuration makes a difference,
    > or it is your hardware.

    Yep. My understanding is the A variant is just a difference of
    microcode, but who knows what affect that could have.

    >
    > I'll try to connect a couple of fans next (so far I did without) and try again.

    Keep me posted if you do.

    Thanks again.

    Andrew

    >
    > Guenter[unhandled content-type:application/pgp-signature]
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