RE: [PATCH v4 3/6] i3c: Add support for mastership request to I3C subsystem

Vitor Soares
2019-04-09T14:32:06Z

Hi Przemek,

From my analyses you do i3c_master_register for secondary master in follow cases:
- HC has already an dynamic address and it is the owner of the bus.
Or
- when it receive MR event enable.

Is this correct?

From: vitor <soares@synopsys.com>
Date: Mon, Apr 01, 2019 at 19:41:39

> Hi Przemek,
>
> > +/**
> > * i3c_master_register() - register an I3C master
> > * @master: master used to send frames on the bus
> > * @parent: the parent device (the one that provides this I3C master
> > * controller)
> > * @ops: the master controller operations
> > - * @secondary: true if you are registering a secondary master. Will return
> > - * -ENOTSUPP if set to true since secondary masters are not yet
> > - * supported
> > + * @secondary: true if you are registering a secondary master.
> > *
> > * This function takes care of everything for you:
> > *
> > @@ -2427,10 +2672,6 @@ int i3c_master_register(struct i3c_master_controller
> *master,
> > struct i2c_dev_boardinfo *i2cbi;
> > int ret;
> >
> > - /* We do not support secondary masters yet. */
> > - if (secondary)
> > - return -ENOTSUPP;
> > -
> > ret = i3c_master_check_ops(ops);
> > if (ret)
> > return ret;

The bus mode is set before the sec master does i3c_master_add_i3c_dev_locked() and
i3c_master_add_i2c_dev() and after that it isn't updated. This can cause troubles for
HDR-TS modes and when you have i2c devices INDEX(2) on the bus.

> > @@ -2504,9 +2745,11 @@ int i3c_master_register(struct i3c_master_controller
> *master,
> > * register I3C devices dicovered during the initial DAA.
> > */
> > master->init_done = true;
> > - i3c_bus_normaluse_lock(&master->bus);
> > - i3c_master_register_new_i3c_devs(master);
> > - i3c_bus_normaluse_unlock(&master->bus);
> > + i3c_master_register_new_devs(master);
> > +
> > + i3c_bus_maintenance_lock(&master->bus);
> > + i3c_master_enable_mr_events(master);

Why are you enabling MR events here? As a standard function this might case issues
because the master can support ENEC/DISEC commands but not multi-master typologies.

> > + i3c_bus_maintenance_unlock(&master->bus);
> >
> > return 0;
> >
> > @@ -2524,6 +2767,30 @@ int i3c_master_register(struct i3c_master_controller
> *master,
> > EXPORT_SYMBOL_GPL(i3c_master_register);
> >

I'm thinking if isn't better to instantiate the bus apart and them register the secondary master.
In this way you are able to add DEFSLVS even before the HC has enable MR events like it is done
with dt devices.

Best regards,
Vitor Soares