From: Arnd Bergmann <arnd@arndb.de>
To: linux-arm-kernel@lists.infradead.org
Cc: Santosh Shilimkar <santosh.shilimkar@ti.com>,
        Rob Herring <robherring2@gmail.com>,
        Mark Rutland <mark.rutland@arm.com>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        Grygorii Strashko <grygorii.strashko@ti.com>,
        Russell King <linux@arm.linux.org.uk>, Pawel Moll <pawel.moll@arm.com>,
        Ian Campbell <ijc+devicetree@hellion.org.uk>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Rob Herring <robh+dt@kernel.org>, Kumar Gala <galak@codeaurora.org>,
        Grant Likely <grant.likely@linaro.org>,
        Fabio Estevam <festevam@gmail.com>,
        Shawn Guo <shawn.guo@freescale.com>
Subject: Re: [PATCH] dt/documentation: add specification of dma bus information
Date: Fri, 20 Jun 2014 20:56:49 +0200
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On Friday 20 June 2014 13:17:43 Santosh Shilimkar wrote:
> >> +                       dma-coherent;
> >> +                       dma-ranges;
> >> +
> >> +                       dwc3@2690000 {
> >> +                               compatible = "synopsys,dwc3";
> >> +                               [...]
> >> +                       };
> > 
> > This example is a bit strange. I don't understand the relationship
> > between keystone-dwc3 and synopsys,dwc3, nor do I want to. I'd prefer
> > to see a simple example here.


> > dma-ranges is a property of the parent which you show, but
> > dma-coherent originally was a property of the bus master itself. While
> > we need to support that, are we changing that? We need to be clear on
> > where the property belongs even if the kernel is more lax.
> > 
> I don't think we are changing it fundamentally but may be I missing
> your point. The dma-coherent as is now a per-device property.
> USB is one of the bus master supports coherency and hence showed
> up in above example.

I think it's enough if you just drop the "synopsys,dwc3" node and the
intermediate dma-ranges property from the example, leaving the
dma-coherent property in the "ti,keystone-dwc3" node.

	Arnd
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