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Message-ID: <CAD=FV=VMBBT0E-7F=F+inThL+hjC8pZCf3707mJaQ0NEKQ_P7Q@mail.gmail.com>
Date: Thu, 17 Jan 2019 09:47:28 -0800
From: Doug Anderson <dianders@...omium.org>
To: Bjorn Andersson <bjorn.andersson@...aro.org>
Cc: Andy Gross <andy.gross@...aro.org>,
David Brown <david.brown@...aro.org>,
Rob Herring <robh+dt@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Stephen Boyd <swboyd@...omium.org>,
linux-arm-msm <linux-arm-msm@...r.kernel.org>,
devicetree@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 2/2] arm64: dts: qcom: sdm845: Extend ranges and
describe DMA space
Hi,
On Wed, Jan 16, 2019 at 8:30 PM Bjorn Andersson
<bjorn.andersson@...aro.org> wrote:
>
> For devices attached to an IOMMU, translation between IOVA and physical
> addresses is no longer 1:1 and dma-ranges should be specified to
> describe the available IOVA address space.
>
> On SDM845 the busses are implemented with 36 address bits, so dma-ranges
> must be defined to reduce the size of the IOVA address space from the 48
> bits supported by the SMMU. Without this DMA allocations may end up with
> IOVAs outside the valid range, that gets truncated by the bus between
> the device and its translation unit.
>
> Also extend ranges to describe the available address space.
>
> Signed-off-by: Bjorn Andersson <bjorn.andersson@...aro.org>
> ---
>
> Changes since v3:
> - Split this out from patch 1.
> - Rewrote commit message from scratch
>
> arch/arm64/boot/dts/qcom/sdm845.dtsi | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
Reviewed-by: Douglas Anderson <dianders@...omium.org>
Tested-by: Douglas Anderson <dianders@...omium.org>
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