[PATCH RFCv1 0/6] ARM: mvebu: coherency support improvements

All,

resending to include the MLs

On Thu, Dec 26, 2013 at 05:29:31PM +0100, Andrew Lunn wrote:

On Thu, Dec 26, 2013 at 05:13:02PM +0100, Thomas Petazzoni wrote:

quoted

Dear Andrew Lunn,

On Thu, 26 Dec 2013 17:08:31 +0100, Andrew Lunn wrote:

quoted

In the .dtsi file i would suggest multiple compatibilities from the
most specific to the most general. So listing:
marvell,armada-370-coherency-fabric,
marvell,armada-370-xp-coherency-fabric,

gives you the most forward/backward compatibility, as you discover
more about the hardware.

True, that's another possibility. Though it's unclear if a compatible
string such as "marvell,armada-370-xp-coherency-fabric" makes sense. If
you create such a compatible string, and then later discover than 370
and XP cannot be handled in a same way, then why have a "shared"
compatible string?

Well presumably, if you need to split it further, it is somehow
broken, or at least not optimal. Anybody who cannot update there DT
blob keeps with the current somehow broken/non-optimal behavior, but
those who can upgrade there DT blob get better behavior.

More compatible strings helps with backward compatibility for old DT
blobs.

Please, let's not over-think this.  Right now, are there _any_
capability differences we're aware of between the two?  If not, then we
should use marvell,armada-370-xp-coherency-fabric.  *after* we discover
an incompatible difference, then we add
marvell,armada-370-coherency-fabric.  The driver, if it sees the new
compatible string, will use the new feature.  If it doesn't, it will
default to the old behavior as it was under
marvell,armada-370-xp-coherency-fabric.

Let's not get ahead of ourselves guessing towards the 'perfect' DT
binding.

thx,

Jason.