Re: [PATCH v6 01/10] i3c: Add core I3C infrastructure

[Boris Brezillon <boris.brezillon@bootlin.com>]

Hi Przemek,

On Tue, 28 Aug 2018 12:55:20 +0000
Przemyslaw Gaj <pgaj@cadence.com> wrote:

> Hi Vitor,
> 
> I have already implemented Mastership request/handover but we are waiting for Boris’s patch to be accepted and merged. Anyway, my comments below.
> 
> On 8/28/18, 2:02 PM, "Boris Brezillon" <boris.brezillon@bootlin.com> wrote:
> 
>     EXTERNAL MAIL
>     
>     
>     Hi Vitor,
>     
>     On Tue, 28 Aug 2018 12:50:12 +0100
>     vitor <Vitor.Soares@synopsys.com> wrote:
>     
>     > Hi Boris,
>     > 
>     > The DT Bindings say "The node describing an I3C bus should be named 
>     > i3c-master.". Do you have a field for secondary master?  
> 
> I think we don’t need separate field for secondary master. Main and secondary masters 
> support similar functionalities. It’s enough to have this state internally and do mastership it it's needed.
> 
>     > 
>     > On 24-08-2018 19:16, Boris Brezillon wrote:  
>     > > Well, before even considering supporting secondary master registration,
>     > > we need to handle mastership handover. As for the DAA operation, it's
>     > > likely to be host specific, so we'll have to add a new hook to the
>     > > i3c_master_controller_ops struct.    
>     > Do you mean when master try to delegate the bus ownership through 
>     > GETACCMST? or to get the bus ownership with IBI-MR?  
>     
>     I think we need to support both.
> 
> I agree.
>     
>     > 
>     > I think that could be useful to pass the ibi type on request_ibi(), 
>     > there is some case where the master doesn't support IBI-MR.  
>     
>     Actually, I was planning on making it completely separate from
>     regular slave IBIs. That is, the master controller driver would demux
>     the slave, MR and Hot Join IBIs, and if there's an MR request, queue a
>     mastership handover work to the workqueue (pretty much what we do for
>     Hot-Join already). Mastership handover is anyway likely to be IP
>     specific, so I don't think there's a need to make it look like a
>     regular IBI.
> 
> I think it's better to have separate function to do mastership request.
>     
>     Regarding whether IBI-MR support should be exposed to the I3C framework
>     or not depends on how much will be automated on the framework side. I
>     don't the answer yet, but that's probably something will figure out
>     along the road.
> 
> My current implementation is: when request_mastership field 
> of i3c_master_controller_ops structure is set, master driver supports mastership requests.
> That's how I check if this is supported or not.

Can you maybe host your code on a public repo (I can push it for you if
needed) so that you and Vitor can start discussing implementation
details.

Thanks,

Boris