Hi all, I had to update the doc/developers/proc document for the lm83 driver (it has four temperature channels). The same change will be needed when the driver makes it into Linux 2.6. Greg, attached is a patch I suggest you apply at the same time you'll apply my lm83 patch to Linux-2.6.0. Some points I'd like to discuss about: 1* Most entries are described using sentences like "Fixed point value in form XXXXX and should be divided by 1000 to get degrees Celsius". I don't understand the "fixed point" thing, nor do I understand the informational value of "in form XXXXX". Wouldn't it be much clearer to write "Integer value, thousandth of degrees Celsius"? 2* temp_min[1-3] reads: "Temperature min or hysteresis value.". This is a Bad Idea (TM) IMHO. One very interesting point in the sysfs interface over the procfs one is that it could be easily be made chip-independant (libsensors and sensors could then be drastically simplified). If the file is named temp_minN, it has to be a min temp. Be it a hysteresis one, let's call the file temp_hystN instead. It's in no way harder to do it that way, and it will be way easier for the interface users (includind ourselves) if we stick to the one name, one use philosophy. 3* One additional note about hysteresis temperatures (and critical temperatures also). Some chips have several temperature channels, but a single hysteresis and/or critical temperature register, common to all channels. For example, the LM83 has four temperature channels, four max values, but one single critical value. The ADM1032 has two temperature channels, two min values, two max values, two critical temperatures, but a single, relative hysteresis value that applies to both critical values. I propose that chips that values that are common to all channels simply have no digit appended. That's how I made it in the lm83 driver. Now, for the hysteresis, that's more complicated, since not only it may apply to one or more channels, but it can also happen to one or more limit, and be relative or absolute. I think that hysteresis files should be named after the limit they are an hysteresis for. In the case of the lm90 driver, we would have the following files: temp1_input temp2_input temp1_min temp2_min temp1_max temp2_max temp1_crit temp2_crit temp_crit_hyst Note that the digit is also omitted, since the value is common to both channels. An hysteresis that would apply to all temperatures of one channel would be named "temp1_hyst". An hysteresis that would apply to more than one channel and more than one limit for each channel would be called temp_hyst. I think you get the idea. Remains the problem of relative hyst vs. absolute hyst temperature. The docs say we should prefer absolute, but in the case of the lm90 driver, it isn't possible (because the hysteresis value applies to two critical limits that can have different values). The only thing I can think of is having different names again. For example, relative hysteresis would be appended _rhyst while absolute ones would be appended _ahyst (or simply _hyst if we want to provide some kind of backward compatibility, or if we consider that absolute values are the default). A very different approach would be to simulate as much values as we need, regardless of how many registers there are. In the case of the lm83 driver, we would have temp1_crit and temp2_crit instead of temp_crit, and both files would access the same register. The advantage of this method is that all future chips will necessarily be supportable, which isn't the case with my first proposal. We could imagine a chip that has four temperature channels, one critical limit for channels 1 and 2, and one critical limit for channels 3 and 4. That's something my first model doesn't handle, while the second does. I can say how likely it is to see such a chip someday. All other scenarios I can think of at the moment are OK with that first model. The drawbacks of the second method are: we break the one-one link between sysfs and the hardware (which helps a lot to understand how a chip works, IMHO), we create more sysfs entries, and writing to a register might have side effects to the other registers (might be already happening in some cases anyway). Another good point is that it solves the relative hysteresis problem mentioned above. Other possibilities may exist (might involve symlinks for example). It would be great to come to a decision before going on with porting chip drivers, methinks. Everyone let me know your opinion about the topic, should you have one. -- Jean Delvare http://www.ensicaen.ismra.fr/~delvare/
