On Fri, 2017-03-31 at 18:33 +0200, Wolfram Sang wrote: > Hi, > > > Did anybody give thoughts to how we could support "smbus" block > > transfers with a size up to 0xff ? This is an extension of smbus > > that part of the PMbus protocol spec. > > For completeness, SMBus Spec V3 (released 2015) increased the allowed > transfer size to 255 as well. > > > > > Our current code has a lot of places where I2C_SMBUS_BLOCK_MAX is > > hard wired. Including down in almost all drivers. > > > > So it would have to be an evolutionary process. > > > > I was thinking a message flag along with a functionality bit > > maybe ? > > I have never really scratched my head about this issue yet and don't > know of any on-going activity. It is notable, though, that we export > I2C_SMBUS_BLOCK_MAX to userspace, too. Right. I don't think we can change it. We could either define a whole new set of block read/write that support "extended" max, or probably easier, a msg flag indicating that this is supported. We would need a backend bus capability as well since all the busses today will barf if the device returns something larger than I2C_SMBUS_BLOCK_MAX. Not a huge deal, all this is just a thought, I don't think I have a device to deal with today that will return more on any of my systems (I can double check later). I just noticed that while reading the PMbus spec. Cheers, Ben. -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
