Messages in this thread |  | | Subject | Re: [PATCH] hwmon: (pmbus/lm25066) Swap low/high current coefficients for LM5066(i) | From | Guenter Roeck <> | Date | Wed, 22 Nov 2017 17:17:44 -0800 |
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Hi Rob,
On 11/22/2017 03:39 PM, Rob Lippert wrote: > On Wed, Nov 22, 2017 at 3:28 PM, Guenter Roeck <linux@roeck-us.net> wrote: >> >> On Wed, Nov 22, 2017 at 02:07:28PM -0800, Robert Lippert wrote: >>> The _L low-current mode coefficient values should reference the >>> datasheet rows with CL=VDD but it seems were mistakenly pulled from >>> the rows with CL=GND. >>> >>> This causes the current/power to be reported as approximately double >>> the actual value when CL=GND and half the actual value when CL=VDD. >>> >> >> This would affect all chips supported by this driver. Hmm, and I was sure >> I tested this. I'll have to dig out my hardware and confirm. > > I'm still not 100% convinced this commit is correct as I haven't been > able to validate the measurements against an external probe yet (and > my test board uses a non-standard sense resistor which means it needs > additional massaging of the data anyhow). > >> >> >> The code currently only uses bit 4 of the DEVICE_SETUP (D9h) command >> to determine which current limit setting to use. Looking into the >> datasheet, it looks like it also has to evaluate bit 2, and I wonder >> if there is a means to determine CL if bit 2 = 0. Any idea ? > > On my test board CL=floating (equivalent to GND) and the value of > register 0xD9 is all zeroes. > Are you sure that floating is equivalent to GND ? I didn't check the datasheet, but it is more common for chips to have an internal pull-up.
>> >> Does bit 4 report the CL pin value if bit 2 = 0 ? > > I can't tell by reading the datasheet that 0xD9 bit4 will ever report > the pin value as the language is difficult to parse :)
Same here.
> But I don't have any hardware setup with CL=VDD to test... >
I do have various evaluation boards, so I should be able to do some testing. I hope I'll get to it over the weekend.
Guenter
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