Re: [PATCH v5 02/10] docs: driver-api: Add I3C documentation

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

Hi Randy,

On Tue, 26 Jun 2018 14:07:49 -0700
Randy Dunlap <rdunlap@infradead.org> wrote:


> > +
> > +I3C Private SDR transfers
> > +-------------------------
> > +
> > +Private SDR (Single Data Rate) transfers should be used for anything that is
> > +device specific and does not require high transfer speed.
> > +
> > +It is the equivalent of I2C transfers but in the I3C world. Each transfer is
> > +passed the device address (dynamic address assigned during DAA), a payload
> > +and a direction.
> > +
> > +The only difference with I2C is that the transfer is much faster (typical SCL  
> 
> what is SCL?  It's not used anywhere else in this doc.

It's an acronym used by I²C, it means Serial Clock Line. I'll just
replace that by "typical clock frequency is 12.5MHz".

> 
> > +frequency is 12.5MHz).
> > +
> > +I3C HDR commands
> > +----------------
> > +
> > +HDR commands should be used for anything that is device specific and requires
> > +high transfer speed.
> > +
> > +The first thing attached to an HDR command is the HDR mode. There are currently
> > +3 different modes defined by the I3C specification (refer to the specification
> > +for more details):
> > +
> > +* HDR-DDR: Double Data Rate mode
> > +* HDR-TSP: Ternary Symbol Pure. Only usable on busses with no I2C devices
> > +* HDR-TSL: Ternary Symbol Legacy. Usable on busses with I2C devices
> > +
> > +When sending an HDR command, the whole bus has to enter HDR mode, which is done
> > +using a broadcast CCC command.
> > +Once the bus has entered a specific HDR mode, the master sends the HDR command.
> > +An HDR command is made of:
> > +
> > +* one 16-bits command word
> > +* N 16-bits data words  
> 
> I supposed the I3C spec will tell me the byte order of these words on the bus?
> or this doc could tell us here.

It's big endian. I'll make it clear in this doc.

I'll also fix all the other mistakes you pointed out.

> 
> and you can add (if you want to):
> Reviewed-by: Randy Dunlap <rdunlap@infradead.org>

I'll definitely add your R-b. Thanks for the review.

Boris