Mark M. Hoffman wrote: > Hi Hans: > >> Jean Delvare wrote: >>> This is absolutely not different from all other hardware monitoring >>> drivers. And all other drivers handle it in user-space, because that's >>> the right design. I see no valid reason why it would be different for >>> your abituguru3 driver. All you need is one configuration file per >>> motherboard. > > * Hans de Goede <j.w.r.degoede at hhs.nl> [2007-04-09 14:50:03 +0200]: >> Oh and yet another thing, since when should all conversions be done in >> userspace? I did exactly that with the abituguru 1/2 driver and there I had to >> change it to give the return the actual pin values in Volts and not register >> values, iow do the conversion in the driver. >> [...] > > The kernel-to-userspace interface for hwmon is the *measured* value at the > *pin*, in natural units. > > If the pin on a chip can measure e.g. 0.0-5.0 volts, then the sysfs file will > report that voltage. > > If that same pin is wired into a circuit which is used for measuring a 12V > power supply (and thus needs further conversion) that is *irrelevant* to the > driver. The hwmon driver for a well-documented and general purpose sensor chip > need not concern itself with external circuitry. > > (It cannot, short of moving all of libsensors or its equivalent into the kernel, > which would be horrible. Even if we could track all mainboard types and > somehow update the kernel with all that info, you still need a way for embedded > people to reconfigure it for their custom boards or whatever. *That* is why > we keep libsensors out of the kernel. Not because of "if it can be done in > userspace, it should" or any nonsense like that.) > > A chip like uguru breaks this model, because we have *no* *idea* what it might > be measuring at the *pin*. But it turns out, it doesn't matter. It's so > tightly coupled to the mainboard that we can treat the whole thing as a "chip". > The embedded case goes away (like I mentioned in another thread) because nobody > is designing the uguru into custom boards anyway. > > I hope this rationale for the kernel/userspace API is clear now. > It is and always was, but as you say the uguru is a bit of a special case here. I've got some good news about the fintek f77882fg / epox ep1308 chipb btw, my student (Hans Edgington) has returned the motherboard and last friday I build a system with it. I also compiled his driver and I've added / fixed reading of the voltages, There I'm doing exactly what you describe above, return a sysfs reading between 0 and 2.048 volts, and then let libsensors scale it depending on the attached divider circuit. I still need to merge the patch for true fintek / msi board support and then I'll post an initial version. Regards, Hans
