Messages in this thread | | | Date | Wed, 16 Feb 2022 07:12:19 -0800 | From | Guenter Roeck <> | Subject | Re: [PATCH v3 2/2] hwmon: Add driver for Texas Instruments TMP464 and TMP468 |
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On 2/16/22 04:42, Agathe Porte wrote: > Hi Guenter, > > Le 16/02/2022 à 08:07, Guenter Roeck a écrit : >> Add support for Texas Instruments TMP464 and TMP468 temperature sensor >> ICs. >> >> TI's TMP464 is an I2C temperature sensor chip. This chip is >> similar to TI's TMP421 chip, but with 16bit-wide registers (instead >> of 8bit-wide registers). The chip has one local sensor and four >> remote sensors. TMP468 is similar to TMP464 but has one local and >> eight remote sensors. >> >> Originally-from: Agathe Porte <agathe.porte@nokia.com> >> Cc: Agathe Porte <agathe.porte@nokia.com> >> Cc: Krzysztof Adamski <krzysztof.adamski@nokia.com> >> Signed-off-by: Guenter Roeck <linux@roeck-us.net> >> --- >> v3: >> - Added support for TMP468 >> - Added support for various limits, temperature hysteresis, alarm attributes, >> and update interval >> - Use regmap instead of local caching >> - Use static chip configuration >> - Unlock check if needed when loading driver, and lock it when unloading it >> - Call tmp464_init_client() before calling tmp464_probe_from_dt() >> since the latter changes registers, which requires the chip to be >> unlocked. >> - Restore configuration register when unloading driver >> - ti,n-factor is optional, so don't fail if the property is not present >> >> Notes: >> - Tested with real TMP468. Module tested for TMP464. >> - I was not able to test with a system supporting devicetree; >> especially negative values for "ti,n-factor" need testing >> (and I wonder if of_property_read_s8() would be needed to >> support this properly). > > I just did the test on our system and both positive and negative value n-factor fails. > > With the following overlay: > > /dts-v1/; > /plugin/; > / { > fragment@0 { > target-path = "/soc/.../i2c@4/tmp464@49"; > __overlay__ { > #address-cells = <1>; > #size-cells = <0>; > > channel@0 { > reg = <0x0>; > label = "local"; > ti,n-factor = /bits/ 8 <(-10)>; > }; > > channel@1 { > reg = <0x1>; > label = "ch1"; > }; > > channel@2 { > reg = <0x2>; > label = "ch2"; > }; > > channel@3 { > reg = <0x3>; > label = "ch3"; > }; > > channel@4 { > reg = <0x4>; > label = "ch4"; > }; > }; > }; > > }; > > I get the following probing error: > > [ 3580.557425] tmp464: probe of 16-0049 failed with error -75 >
I think that may be caused by using of_property_read_s32() for reading an 8-bit property. Can you try and replace of_property_read_s32() with of_property_read_u8() and the variable it points to to s8 ?
s8 val; ... err = of_property_read_u8(child, "ti,n-factor", &val);
There is no of_property_read_s8(), so we can not use that, but maybe using of_property_read_u8() does the trick.
Thanks, Guenter
> With a positive n-factor in the overlay (<(10)> instead of <(-10)>), the driver *does not load either*, with the same error message. > > Without any n-factor set, the v3 driver you proposed loads just fine with the DT. > > Any idea of where this could come from? This was probably not working in my own implementation either. > > PS: check your spam folder eventually for my mail asking delivery details of the TMP464 samples. > > Bests, > > Agathe. >
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