linux-kernel - Re: [PATCH v2 06/11] ARM: dts: zynq: Add DMAC for Parallella

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Date:	Fri, 25 Jul 2014 07:43:44 -0700
From:	Sören Brinkmann <soren.brinkmann@...inx.com>
To:	Andreas Färber <afaerber@...e.de>
CC:	<monstr@...str.eu>, Michal Simek <michal.simek@...inx.com>,
	Andreas Olofsson <andreas@...pteva.com>,
	Matteo Vit <matteo.vit@...rwaredesign.com>,
	Sean Rickerd <srickerd@...e.com>, <devicetree@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>, Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Russell King <linux@....linux.org.uk>
Subject: Re: [PATCH v2 06/11] ARM: dts: zynq: Add DMAC for Parallella

On Fri, 2014-07-25 at 10:24AM +0200, Andreas Färber wrote:
> Am 25.07.2014 10:02, schrieb Michal Simek:
> > On 07/25/2014 01:28 AM, Sören Brinkmann wrote:
> >> On Fri, 2014-07-25 at 01:00AM +0200, Andreas Färber wrote:
> >>> Signed-off-by: Andreas Färber <afaerber@...e.de>
> >>> ---
> >>>  v2: New
> >>>  
> >>>  arch/arm/boot/dts/zynq-7000.dtsi      | 17 +++++++++++++++++
> >>>  arch/arm/boot/dts/zynq-parallella.dts |  4 ++++
> >>>  2 files changed, 21 insertions(+)
> >>>
> >>> diff --git a/arch/arm/boot/dts/zynq-7000.dtsi b/arch/arm/boot/dts/zynq-7000.dtsi
> >>> index eed3df0..1a70277 100644
> >>> --- a/arch/arm/boot/dts/zynq-7000.dtsi
> >>> +++ b/arch/arm/boot/dts/zynq-7000.dtsi
> >>> @@ -223,6 +223,23 @@
> >>>  			};
> >>>  		};
> >>>  
> >>> +		dmac_s: dmac@...03000 {
> >>> +			compatible = "arm,pl330", "arm,primecell";
> >>> +			reg = <0xf8003000 0x1000>;
> >>> +			status = "disabled";
> >> I think for this IP we can omit the 'status' property since it is always
> >> enabled. I don't see a reason to override it in each board DT.
> > 
> > Done this change myself
> 
> Fine with me, but allow me to point out that the TRM documents the DMAC
> being mapped as DMAC S at the above address, and as DMAC NS at F800_4000
> (secure vs. non-secure, ch. 4.6, p. 116). Not sure how this would be
> handled driver-wise if not through alternative dt nodes?

The upstream Linux runs in secure state on Zynq, hence I think this is fine. If
somebody wants to run Linux on Zynq non-secure they have to do some work
anyhow. This way the standard configuration can use the DMA engine.

	Sören

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