[PATCH v5 2/4] ARM: mvebu: Add quirk for i2c for the OpenBlocks AX3-4 board

[Jason Cooper]

On Fri, Jan 10, 2014 at 10:21:29PM +0100, Gregory CLEMENT wrote:
> On 10/01/2014 22:14, Jason Cooper wrote:
> > On Fri, Jan 10, 2014 at 09:12:41PM +0100, Gregory CLEMENT wrote:
> >> Jason,
> >> On 10/01/2014 21:08, Jason Cooper wrote:
> >>> On Fri, Jan 10, 2014 at 02:45:50PM -0500, Jason Cooper wrote:
> >>>> On Fri, Jan 10, 2014 at 12:05:21PM -0700, Jason Gunthorpe wrote:
> >>>>> On Fri, Jan 10, 2014 at 01:22:40PM -0500, Jason Cooper wrote:
> >>>>>
> >>>>>> Do we create new compatible strings to indicate errata, or to indicate
> >>>>>> 'from this version forward there are new features'?  The former would
> >>>>>> indicate as Gregory has written '...-a0-i2c', the latter would warrant
> >>>>>> '...-b0-i2c' and disabling offloading if we don't see '...-b0-i2c'.
> >>>>
> >>>> s/-b0-i2c'./-b0-i2c' or newer./
> >>>>
> >>>>> IMHO the compatible string should represent a specific HW/SW ABI. So
> >>>>> you need a unique compatible string for every variation of that ABI.
> >>>>
> >>>> My concern is that we tend to do things like "marvell,orion-sata" for
> >>>> the first version of the IP block we can work with.  orion5x, kirkwood,
> >>>> dove, and armada 370/xp all use that compatible string to refer to that
> >>>> IP block.
> >>>>
> >>>> Given that we look at it as 'and newer', '...-a0-i2c' would mean no
> >>>> offloading until we introduce '-b0-i2c'.  Or am I mis-understanding what
> >>>> you're saying?
> >>>>
> >>>>> We already have a compatible string defined for the ABI that B0
> >>>>> presents.
> >>>>
> >>>> So 'mv78230-i2c' is newer than 'mv78230-a0-i2c', or are you referring to
> >>>> something else?
> >>>
> >>> I think the crux of it is:  Is mv78230-i2c the first, or the default?
> >>
> >> Here it's clearly the default
> > 
> > So we should default to no offloading when we see it?  Since it has been
> > deployed referring to -a0 revision i2c IP blocks?
> > 
> 
> But this assumption is wrong as I already wrote few days ago, mv78230-i2c
> has been deployed referring to -b0 revision i2c IP blocks since the begining.

Ok, sorry.  As I wrote on irc last week, I've been on travel and haven't
been able to fully digest everything coming in.  My re-read of all the
threads regarding this this morning didn't catch it.

> It was developed on and for B0 version, and this compatible was created for
> this specific version. It was latter that we realized that it was not fully
> compatible with A0. But for sure:
> 
> mv78230-i2c == I2C IP running on Armada XP B0 (or latter)

Ok, this still feels counter-intuitive, and folks not familiar with the
development process might assume the opposite.  So I'll reply to 4/4
with a reword to make your above statement an explicit part of the
binding documentation.  No need to do another patch version.  I'll fix
it up when I pull it in if you're ok with it.

thx,

Jason.