RE: [PATCH v2 1/5] i3c: master: detach and free device if pre_assign_dyn_addr() fails
From: Vitor Soares
Date: Wed Sep 04 2019 - 05:06:46 EST
From: Przemyslaw Gaj <pgaj@xxxxxxxxxxx>
Date: Wed, Sep 04, 2019 at 05:47:18
> The 09/03/2019 11:57, Vitor Soares wrote:
> > EXTERNAL MAIL
> > From: Przemyslaw Gaj <pgaj@xxxxxxxxxxx>
> > Date: Tue, Sep 03, 2019 at 12:13:57
> > > Hi Vitor,
> > >
> > > I'm sorry for the delay.
> > >
> > > The 09/03/2019 12:35, Vitor Soares wrote:
> > > > EXTERNAL MAIL
> > > >
> > > >
> > > > On pre_assing_dyn_addr() the devices that fail:
> > > > i3c_master_setdasa_locked()
> > > > i3c_master_reattach_i3c_dev()
> > > > i3c_master_retrieve_dev_info()
> > > >
> > > > are kept in memory and master->bus.devs list. This makes the i3c devices
> > > > without a dynamic address are sent on DEFSLVS CCC command. Fix this by
> > > > detaching and freeing the devices that fail on pre_assign_dyn_addr().
> > >
> > > What is the problem with sending devices without dynamic address in DEFSLVS?
> > How do you address them?
> > For the DA field in DEFSLVS frame, the spec says: "shall contain the
> > current value of the Slave's assigned 7-bit Dynamic address". If the
> > device doesn't have the dynamic address assigned yet why send it?
> What stops us from operating with this device in I2C mode using his SA?
So, send it as an I2C device as spec says.
> > > Shouldn't we still inform rest of the devices about that? About fact that
> > > device with SA without DA exists on the bus?
> > I would like to understand what is the use case for this?
> Look above. I2C mode still should be possible IMO. Just consider the case when
> you really need some information from that device, main master can assign
> dynamic address later but you can make some transfers.
It is true, but again it is a I2C device and not I3C device. It won't
reply to I3C commands until has a DA.
How will you know that the DA sent in DEFSLVS is not assigned yet?
> I know our framework
> does not support that case but secondary master can be different system which
> should know that this device exists and don't have DA yet, so I2C mode is
If the HJ happen in secondary master side, there is a change to describe
in DT what should be DA. Please check 2nd patch.
> > On I3C spec table "I3C Devices Roles vs Responsibilities", Secondary
> > Master is not responsible to do Dynamic Address Assignment but it is
> > optional to do Hot-Join Dynamic Address Assignment.
> Yes, we discussed that few times during the review of Mastership patch series.
Hence, based on that table, secondary master won't do DAA just because he
want, It needs a HJ to trigger DAA.
Sorry, but for me based on what spec says this use case is not feasible.