On Mon, 31 Jul 2017 21:17:45 +0200 Wolfram Sang <wsa@xxxxxxxxxxxxx> wrote: > Hi Boris, > > > This patch series is a proposal for a new I3C [1] subsystem. > > Nice. Good luck with that! > > Some hi-level comments from me related to I2C. I can't say a lot more > because the specs are not public :( > > > - the bus element is a separate object and is not implicitly described > > by the master (as done in I2C). The reason is that I want to be able > > to handle multiple master connected to the same bus and visible to > > Linux. > > In this situation, we should only have one instance of the device and > > not one per master, and sharing the bus object would be part of the > > solution to gracefully handle this case. > > I'm not sure if we will ever need to deal with multiple masters > > controlling the same bus and exposed under Linux, but separating the > > bus and master concept is pretty easy, hence the decision to do it > > now, just in case we need it some day. > > From my experience, it is a good thing to have this separation. > > > - I2C backward compatibility has been designed to be transparent to I2C > > drivers and the I2C subsystem. The I3C master just registers an I2C > > adapter which creates a new I2C bus. I'd say that, from a > > representation PoV it's not ideal because what should appear as a > > single I3C bus exposing I3C and I2C devices here appears as 2 > > different busses connected to each other through the parenting (the > > I3C master is the parent of the I2C and I3C busses). > > On the other hand, I don't see a better solution if we want something > > that is not invasive. > > I agree this is the least invasive and also the most compatible > approach. The other solution would probably be to have some kind of > emulation layer? > > > I'd also like to get feedback on the doc. Should I detail a bit more > > the protocol or the framework API? Is this the kind of things you > > expect in a subsystem doc? > > Since the spec is not public, details about the protocol will be > especially useful, I'd say. MIPI has opened the I3C spec [1], it can be downloaded here [2]. v2 of this series will come soon (sorry for the delay). Regards, Boris [1]https://www.businesswire.com/news//home/20171212005059/en/MIPI-Alliance-Opens-Access-MIPI-I3C-Sensor [2]http://resources.mipi.org/mipi-i3c-v1-download
