linux-kernel - Re: [PATCH 0/2] soc: ti: k3-ringacc: Add additional register regions

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Message-ID: <cb5e3bbe-19d4-4989-adaf-5b7827982184@gmail.com>
Date:   Fri, 11 Aug 2023 18:20:33 +0300
From:   Péter Ujfalusi <peter.ujfalusi@...il.com>
To:     Vignesh Raghavendra <vigneshr@...com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>, Nishanth Menon <nm@...com>,
        Tero Kristo <kristo@...nel.org>
Cc:     Santosh Shilimkar <ssantosh@...nel.org>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 0/2] soc: ti: k3-ringacc: Add additional register regions

Hi Vignesh,

On 09/08/2023 20:59, Vignesh Raghavendra wrote:
> Ringacc on TI K3 SoCs have configuration registers region which is
> usually hidden from Linux and configured via Device Manager Firmware
> APIs. But certain early SWs like bootloader which run before Device
> Manager is fully up would need to directly configure these registers and
> thus require to be in DT description.
> 
> This add bindings for the cfg region and also adds them to DT files.
> Backward compatibility is maintained to existing DT by only mandating
> existing regions to be present and this new region as optional.
> 
> Nishanth: I am hoping its possible for you to take bindings and DT
> via k3-dts-next once reviewed.

I have similar concern/question as for the DMA side, let me copy that
here as well:
These regions were 'hidden' from Linux or other open coded access for a
reason.
If I recall the main reason is security and the need to make sure that
the allocation of the channels not been violated.

IMho the boot loader should be no exception and it should be using the
DM firmware to configure the DMAs.

Or has the security concern been dropped and SW can do whatever it wants?

> 
> Vignesh Raghavendra (2):
>    dt-bindings: soc: ti: k3-ringacc: Describe cfg reg region
>    arm64: dts: ti: k3: Add cfg reg region to ringacc node
> 
>   Documentation/devicetree/bindings/soc/ti/k3-ringacc.yaml | 9 +++++++--
>   arch/arm64/boot/dts/ti/k3-am65-main.dtsi                 | 5 +++--
>   arch/arm64/boot/dts/ti/k3-am65-mcu.dtsi                  | 6 ++++--
>   arch/arm64/boot/dts/ti/k3-j7200-main.dtsi                | 5 +++--
>   arch/arm64/boot/dts/ti/k3-j7200-mcu-wakeup.dtsi          | 6 ++++--
>   arch/arm64/boot/dts/ti/k3-j721e-main.dtsi                | 5 +++--
>   arch/arm64/boot/dts/ti/k3-j721e-mcu-wakeup.dtsi          | 5 +++--
>   arch/arm64/boot/dts/ti/k3-j721s2-main.dtsi               | 5 +++--
>   arch/arm64/boot/dts/ti/k3-j721s2-mcu-wakeup.dtsi         | 5 +++--
>   arch/arm64/boot/dts/ti/k3-j784s4-main.dtsi               | 5 +++--
>   arch/arm64/boot/dts/ti/k3-j784s4-mcu-wakeup.dtsi         | 5 +++--
>   11 files changed, 39 insertions(+), 22 deletions(-)
> 

-- 
Péter