From mboxrd@z Thu Jan  1 00:00:00 1970
From: vinod.koul@intel.com (Vinod Koul)
Date: Wed, 19 Aug 2015 22:30:45 +0530
Subject: [PATCHv4 3/6] dmaengine: mv_xor: remove support for dmacap,* DT
 properties
In-Reply-To: <20150727124405.53752fe2@free-electrons.com>
References: <1436365699-6862-1-git-send-email-thomas.petazzoni@free-electrons.com>
 <1436365699-6862-4-git-send-email-thomas.petazzoni@free-electrons.com>
 <20150722051653.GR23525@localhost>
 <20150727124405.53752fe2@free-electrons.com>
Message-ID: <20150819170045.GK13546@localhost>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Mon, Jul 27, 2015 at 12:44:05PM +0200, Thomas Petazzoni wrote:
> Vinod,
> 
> On Wed, 22 Jul 2015 10:46:53 +0530, Vinod Koul wrote:
> 
> > >  	xor01 {
> > >  	      interrupts = <52>;
> > > -	      dmacap,memcpy;
> > > -	      dmacap,xor;
> > > -	      dmacap,memset;
> > I maybe wrong but there was an assumption that DT properties, even if bad
> > are always there as they need to be treated as kernel ABI.
> > 
> > How will it work if someone has older DT implementation or older driver?
> 
> Supporting a new DT with an old kernel has never been part of the
> requirements of the DT ABI stability.
> 
> Supporting an old DT with a new kernel is the actual requirement. And
> the patch I'm proposing does not break this at all: a new kernel will
> simply ignore those dmacap,* properties from an old DT, and the driver
> automatically knows by itself what are the capabilities of the
> different XOR engines.
> 
> Therefore, there is no backward compatibility issue introduced by this
> patch.

Yes tht is correct

-- 
~Vinod