Hi Greg, On Mon, 8 Oct 2018 12:47:21 +0200 Arnd Bergmann <arnd@xxxxxxxx> wrote: > On Wed, Oct 3, 2018 at 3:22 PM Boris Brezillon > <boris.brezillon@xxxxxxxxxxx> wrote: > > > > Sorry for the huge delay between v7 and v8 despite the small amount of > > things I was asked to fix/rework. > > > > This patch series is adding a new subsystem to support I3C devices. > > > > This is just adding support for basic features. Extra features will > > be added afterwards. > > > > There are a few design choices that are worth mentioning because they > > impact the way I3C device drivers can interact with their devices: > > > > - all functions used to send I3C/I2C frames must be called in > > non-atomic context. Mainly done this way to ease implementation, but > > this is still open to discussion. Please let me know if you think it's > > worth considering an asynchronous model here > > - the I3C bus and I3C master controller are now tightly coupled even > > though they're still allocated separately. There's now a 1:1 > > relationship between these objects, and the I3C master is no longer > > represented under the I3C bus object. > > Arnd, let me know if you had something different in mind, and I'll > > rework the implementation accordingly. > > I looked at the entire series again and I'm rather happy with how > it turned out. I've commented on a tiny issue about the readsl() > that should be easy to resolve one way or another, with that > you can add my > > Reviewed-by: Arnd Bergmann <arnd@xxxxxxxx> > > There is one additional issue that we've talked about previously > and that I'd like to hear about from GregKH or maybe other > subsystem maintainers: In the current version, you have a single > 'bus_type' object, and this is used to represent both a 'host' and > a 'device'. I think we concluded that this is done in other > subsystems as well, and that this is fitting here because a > host (master device) can hand over being a master to another > device (slave), which then becomes the host and sees this > one as a slave. Also a lot of the sysfs attributes are the same > because of this relationship. > > It also means that you get a mix of things in sysfs: > > /sys/devices/i3c/<bus> > /sys/devices/i3c/<device> > /sys/devices/i3c/<bus>/<device> > > which is a bit like what we have on USB where we can have hub > devices that are again parents of other USB devices, but I don't > think we can have i3c hubs or multiplexers in the same way, so > it's only a single level. > > I'm ok with this model after our previous discussion and couldn't > come up with a better one. If anyone else still sees it as > problematic and has a better idea, please let us know now. I know you're quite busy with the 4.19 release, but if you find a bit of time, that'd be great to have your feedback on this. Thanks, Boris
