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

Sören Brinkmann
2014-07-25T14:43:59Z

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@suse.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@f8003000 {
> >>> + 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