linux-kernel - Re: [PATCH 0/3] dt-bindings: dma: ti: k3* : Update optional reg regions

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Message-ID: <00bf501f-6829-4be3-bf1d-40ae8495d970@gmail.com>
Date:   Sun, 27 Aug 2023 10:18:56 +0300
From:   Péter Ujfalusi <peter.ujfalusi@...il.com>
To:     Vignesh Raghavendra <vigneshr@...com>,
        Vinod Koul <vkoul@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>
Cc:     dmaengine@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 0/3] dt-bindings: dma: ti: k3* : Update optional reg
 regions

Hi Vignesh,

On 11/08/2023 19:04, Vignesh Raghavendra wrote:
> 
> There is been a relook at the arch post this driver was upstreamed. 
> System firmware (SYSFW) is now two separate components:  TI Foundational 
> Security (TIFS) running in a secure island and Device Management (DM) 
> firmware (runs on boot R5 core) [0] shows boot flow diagram for AM62x.

I see, I cannot argue with that.
Is this change affecting the entire K3 family or only the new members?
If the later then I would seek for conditionality for the new regions as
non relooked SoCs these regions are off-limit for the SW.

> Security critical items such as PSIL pairing, channel firewalls and 
> credential configurations are under TIFS and is handled via TI SCI calls 
> at all times.
> 
> But, things related to resource configuration (to ensure different cores 
> dont step on each other) is under DM. Linux still needs to talk to DM 
> for configuring these regions. But, when primary bootloader (R5 SPL) is 
> running, there isn't a DM firmware (as it runs on the same core after R5 
> SPL), it would need to configure DMA resources on its own. 
> 
> This update is mainly to aid R5 SPL to reuse kernel DT as is. 
> Hope that helps

Right, so Linux will need to use these soon ;)

> 
> 
> [0] https://u-boot.readthedocs.io/en/latest/board/ti/am62x_sk.html?highlight=am62#boot-flow
> (Similar boot flow for rest of K3 devices barring am65 and am64)

OK, if the R5 needs to use DMA before DM then surely there is a need to
configure the channel(s).
I expect that R5 or DM will reset things back before booting the main CPU.

> 
>>
>>>
>>> Vignesh Raghavendra (3):
>>>    dt-bindings: dma: ti: k3-bcdma: Describe cfg register regions
>>>    dt-bindings: dma: ti: k3-pktdma: Describe cfg register regions
>>>    dt-bindings: dma: ti: k3-udma: Describe cfg register regions
>>>
>>>   .../devicetree/bindings/dma/ti/k3-bcdma.yaml  | 25 +++++++++++++------
>>>   .../devicetree/bindings/dma/ti/k3-pktdma.yaml | 18 ++++++++++---
>>>   .../devicetree/bindings/dma/ti/k3-udma.yaml   | 14 ++++++++---
>>>   3 files changed, 43 insertions(+), 14 deletions(-)
>>>
>>
> 

-- 
Péter