>> >> New driver to support temperature and voltage sensors embedded inside >> >> the VIA C7 CPU. >> > >> > Is it really an analog voltage sensor? Or does it simply reflect the >> > value of the VID pins? The conversion formula "(data->in << 4) + 700" >> > corresponds to VRM case 13 in hwmon-vid.c, which is what the C7 uses. >> > This makes me suspect that the latter is true. If I am right then the >> > attribute should be named cpuN_vid rather than in0_input. >> >> The datasheet states that this register value is a copy of the MSR >> 0x198 value (performance status register). The bios writting guide >> labels 0x198 as 'current value' whereas MSR 0x199 (performance >> control register) is labeled as 'desired value'. Unless I'm >> misinterpreting taiwanese english, I'd say it's a measured value :-) > > Not necessarily. The CPU knows what voltage value it wants, and tells > that to the voltage regulation unit (through binary VID outputs). The > voltage regulation unit may allow the user to override the CPU voltage, > in either relative or absolute way. Then the voltage regulation unit > could export the actual VID value back to the CPU (through binary VID > inputs from the CPU's perspective.) > > The best way to find out would be to check the CPU datasheet (if you > have it) to find out what pins are related to MSR 0x198. If the value > is obtained by analog-to-digital conversion of Vcore, you don't need > any dedicated pin on the CPU. If OTOH this is a feedback of the VID > value, then you should see 5 pins dedicated to VID input. The datasheet isn't very elaborate on that topic but the CPU doesn't have any VID inputs, only 6 outputs. ...juerg > -- > Jean Delvare >
