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Date: Thu, 7 Sep 2017 19:17:11 -0700 From: Guenter Roeck <linux@...ck-us.net> To: Andrew Jeffery <andrew@...id.au> Cc: linux-hwmon@...r.kernel.org, jdelvare@...e.com, corbet@....net, linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org, openbmc@...ts.ozlabs.org, joel@....id.au Subject: Re: [PATCH] hwmon: pmbus: Make reg check and clear faults functions return errors 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. Either it is because my chip is a MAX31785 (not A), or the configuration makes a difference, or it is your hardware. I'll try to connect a couple of fans next (so far I did without) and try again. Guenter
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