On 08/15/2019 01:48 PM, Wolfram Sang wrote: >> Well, the other option is to remove it, and then add it back once >> somebody complains - which is unlikely to happen. The clock parameter >> is PCF8584 specific anyway, and I think removing it is a good option, > > My suggestion is to do that incrementally. First, get your driver > accepted. Second, do the cleanups which affect elektor as well later. My suggestion is to not touch i2c-elektor at all for now, and remove the 'clock' parameter from the first iteration of i2c-icy. It can be added back in case someone complains, which I deem unlikely. >> as I've done the same with getown() (where in i2c-elektor, 'own' sets >> the PCF8584's own address). > > I wondered about that. Can the PCF8584 really act as a slave, too? > Somewhen I need to check its datasheet. Yes it can, but this driver does not implement this. In fact, I just remembered that the own address, while set, is not used at all in master mode! Quote from the datasheet: https://www.nxp.com/docs/en/data-sheet/PCF8584.pdf 6.4 Own address register S0' When the PCF8584 is addressed as slave, this register must be loaded with the 7-bit I 2 C-bus address to which the PCF8584 is to respond. During initialization, the own address register S0' must be written to, regardless whether it is later used. >> Question is, if I remove the parameter, I'd like it to be >> non-destructive. Do you know of anything that can go wrong if the I2C >> master is running the bus on a wrong clock? > > Not sure if I understand you correctly, but if the bus freq is too fast > then devices won't respond. Too slow is not a problem. Okay, so we don't care. Cool, then it's safe to kick the 'clock' parameter from i2c-icy. All 2019 boards (which should be the vast majority in existence) came with a 12 MHz oscillator AFAIK, so the default should be good. Max
