Re: [PATCH 2/2] i3c/master: add the mipi-i3c-hci driver

Boris Brezillon
2020-08-20T17:14:30Z

On Thu, 20 Aug 2020 12:47:49 -0400 (EDT)
Nicolas Pitre <nico@fluxnic.net> wrote:

> On Thu, 20 Aug 2020, Boris Brezillon wrote:
>
> > On Thu, 20 Aug 2020 10:08:29 +0200
> > Miquel Raynal <miquel.raynal@bootlin.com> wrote:
> >
> > > > + /*
> > > > + * TODO: Extend the subsystem layer to allow for registering
> > > > + * new device and provide BCR/DCR/PID at the same time.
> > >
> > > Not sure this is needed if you don't use it directly as the core will
> > > anyway (in its current form) send the relevant CCC to read these
> > > registers.
> >
> > We considered optimizing that in the past but that means making the DAA
> > and SETDASA registration different. I'm not sure it's worth it to be
> > honest, PID/DCR/BCR only happens when initializing devices and I
> > suspect the overhead of querying those DATA twice in case of DAA is
> > negligible anyway.
>
> Wellllll... I know some people who do feel strongly about this
> particular issue for some reasons.

Mind developing a bit why? Boot-time maybe?

> So I'd prefer giving them some hope
> and leave the door open to some i3c_master_add_i3c_dev_and_info()
> interface. In the end, it's just a matter of pre-filling the info struct
> and skipping the PID retrieval in i3c_master_getpid_locked() if already
> available, etc.

I'm definitely not closing the door, but I'd like to understand why this
is so important to them :-). Anyway, if the changes are not invasive, I
don't have a good reason to refuse it.