using MADC

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1

Hello,

I have a rev. B beagle-xm and I can read out the MADC voltage levels under
/sys/devices/platform/twl4030_madc_hwmon without problem

what puzzles me is that SEL_MADC_MCPC in the CARKIT_ANA_CTRL register of the TPS65950 PMIC is NOT set, and I still can read meaningful values

on a similar board (but with a different revision of the TPS65950) I can NOT get reasonable MADC voltage levels (they are always close to zero);
this second board works as soon as I set SEL_MADC_MCPC

as far as I understand the TRM of the TPS65950, SEL_MADC_MCPC should be set

is this a known issue of the TPS65950?
which TPS65950 revision are used for beagle-xms?
I tried to look up errata, but found no matching issue on record

my beagle-xm rev. B has a TPS65950B E1, the other PMIC is marked TPS65950A3 G1

thanks, regards, p.

2

Hello,

I have a rev. B beagle-xm and I can read out the MADC voltage levels
under
/sys/devices/platform/twl4030_madc_hwmon without problem

what puzzles me is that SEL_MADC_MCPC in the CARKIT_ANA_CTRL register
of the TPS65950 PMIC is NOT set, and I still can read meaningful values

on a similar board (but with a different revision of the TPS65950) I
can NOT get reasonable MADC voltage levels (they are always close to
zero);

I have a rev.C beagleboard-xm with a TPS65950A2 G1 and, with default Angstrom 3.2.28 kernel, I have the same problem.

With this patch [1], I can read voltage levels correctly.

Davide

this second board works as soon as I set SEL_MADC_MCPC

as far as I understand the TRM of the TPS65950, SEL_MADC_MCPC should
be set

is this a known issue of the TPS65950?
which TPS65950 revision are used for beagle-xms?
I tried to look up errata, but found no matching issue on record

my beagle-xm rev. B has a TPS65950B E1, the other PMIC is marked
TPS65950A3 G1

thanks, regards, p.
--

[1] http://lists.lm-sensors.org/pipermail/lm-sensors/2011-December/034426.html

3

> can NOT get reasonable MADC voltage levels (they are always close to
> zero);
I have a rev.C beagleboard-xm with a TPS65950A2 G1 and, with default Angstrom
3.2.28 kernel, I have the same problem.
With this patch [1], I can read voltage levels correctly.
[1] http://lists.lm-sensors.org/pipermail/lm-sensors/2011-December/034426.html

thanks for the pointer, the discussion is quite interesting

p.