linux-kernel - Re: [PATCH v6 2/3] i3c: master: Extend address status bit to 4 and add I3C_ADDR_SLOT_EXT

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Message-ID: <20241004182229.6e08d02c@xps-13>
Date: Fri, 4 Oct 2024 18:22:29 +0200
From: Miquel Raynal <miquel.raynal@...tlin.com>
To: Frank Li <Frank.li@....com>
Cc: Alexandre Belloni <alexandre.belloni@...tlin.com>,
 linux-i3c@...ts.infradead.org, linux-kernel@...r.kernel.org, arnd@...db.de,
 bbrezillon@...nel.org, boris.brezillon@...labora.com,
 conor.culhane@...vaco.com, gregkh@...uxfoundation.org, imx@...ts.linux.dev,
 pthombar@...ence.com, ravindra.yashvant.shinde@....com
Subject: Re: [PATCH v6 2/3] i3c: master: Extend address status bit to 4 and
 add I3C_ADDR_SLOT_EXT_DESIRED

Hi Frank,

> > > @@ -1918,9 +1959,10 @@ static int i3c_master_bus_init(struct i3c_master_controller *master)
> > >  			goto err_rstdaa;
> > >  		}
> > >
> > > -		i3c_bus_set_addr_slot_status(&master->bus,
> > > -					     i3cboardinfo->init_dyn_addr,
> > > -					     I3C_ADDR_SLOT_I3C_DEV);
> > > +		i3c_bus_set_addr_slot_status_mask(&master->bus,
> > > +						 i3cboardinfo->init_dyn_addr,
> > > +						 I3C_ADDR_SLOT_I3C_DEV | I3C_ADDR_SLOT_EXT_DESIRED,
> > > +						 I3C_ADDR_SLOT_EXT_STATUS_MASK);  
> >
> > However I'm not sure I understand the use of the
> > set_addr_slot_status_mask() function. Can't we just use the normal
> > function and just extend the mask in the fist place?  
> 
> The major purpose of set_addr_slot_status_mask() is that reduce code
> change. There are already address alloc/free by using I3C_ADDR_SLOT_FREE.
> 
> we don't want i3c_bus_set_addr_slot_status() touch bit
> I3C_ADDR_SLOT_EXT_DESIRED since it was init at scan dts.

I agree, but in general you will never remove any "desired" slot, so
the "set status", besides at init time, should never touch these extra
bits?

> There are 18 place, using i3c_bus_set_addr_slot_status(), but we only need
> touch I3C_ADDR_SLOT_EXT_DESIRED bit when scan dts.
> 

Thanks,
Miquèl