Re: hwmon: (nct7802) buggy VSEN1/2/3 alarm

Guenter Roeck
2019-11-25T14:31:18Z

On 11/25/19 5:13 AM, Gilles Buloz wrote:
> Hi Guenter,
>
> According to the NCT7802Y datasheet, the REG_VOLTAGE_LIMIT_LSB definition is wrong and leads to wrong threshold registers used. It
> should be :
> static const u8 REG_VOLTAGE_LIMIT_LSB[2][5] = {
> { 0x46, 0x00, 0x40, 0x42, 0x44 },
> { 0x45, 0x00, 0x3f, 0x41, 0x43 },
> };
> With this definition, the right bit is set in "Voltage SMI Status Register @0x1e" for each threshold reached (using i2cget to check)
>

Good catch. Care to send a patch ?

> But I'm unable to get any "ALARM" reported by the command "sensors" for VSEN1/2/3 = in2,in3,in4 because status for in0 is read
> before (unless I set "ignore in0" in sensors file). The problem is that status bits in "Voltage SMI Status Register @0x1e" are
> cleared when reading, and a read is done for each inX processed, so only the first inX has a chance to get its alarm bit set.
> For this problem I don't see how to fix this easily; just to let you know ...
>
One possible fix would be to cache each alarm register and to clear the cache
either after reading it (bitwise) or after a timeout. The latter is probably
better to avoid stale information.

Guenter