Re: [PATCH v5 01/10] i3c: Add core I3C infrastructure

[Peter Rosin]

On 2018-06-22 12:49, Boris Brezillon wrote:
> Add core infrastructure to support I3C in Linux and document it.
> 
> This infrastructure is not complete yet and will be extended over
> time.
> 
> 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 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 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
>   like that.
>   The other benefit of separating the bus and master concepts is that
>   master devices appear under the bus directory in sysfs.

Are bus multiplexers relevant to I3C? The locking needed for handling
muxes for I2C is, well, convoluted...

Cheers,
Peter