linux-kernel - Re: [PATCH RFC] riscv: dts: spacemit: Add DMA translation buses for K1

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <fd9b3bbc-3318-4845-90ca-7f245049665e@iscas.ac.cn>
Date: Tue, 17 Jun 2025 18:10:48 +0800
From: Vivian Wang <wangruikang@...as.ac.cn>
To: Krzysztof Kozlowski <krzk@...nel.org>,
 Vivian Wang <wangruikang@...as.ac.cn>, Yixun Lan <dlan@...too.org>,
 Guodong Xu <guodong@...cstar.com>, Ze Huang <huangze@...t.edu.cn>,
 spacemit@...ts.linux.dev
Cc: Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>, Paul Walmsley
 <paul.walmsley@...ive.com>, Palmer Dabbelt <palmer@...belt.com>,
 Albert Ou <aou@...s.berkeley.edu>, Alexandre Ghiti <alex@...ti.fr>,
 devicetree@...r.kernel.org, linux-riscv@...ts.infradead.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFC] riscv: dts: spacemit: Add DMA translation buses for
 K1

On 6/17/25 17:35, Krzysztof Kozlowski wrote:
> On 17/06/2025 10:48, Vivian Wang wrote:
>> Hi Krzysztof,
>>
>> On 6/17/25 14:21, Krzysztof Kozlowski wrote:
>>> On 17/06/2025 07:21, Vivian Wang wrote:
>>>> The SpacemiT K1 has various static translations of DMA accesses. Add
>>>> these as simple-bus nodes. Devices actually using these translation will
>>>> be added in later patches.
>>>>
>>>> The bus names are assigned according to consensus with SpacemiT [1].
>>> Read the feedback there:
>>>
>>> "So, as you are submitting the first node(s) under network_bus: bus@5, you
>>> should have this added into your patchset, instead of sending out with
>>> none."
>> As mentioned in the patch extra message, this is an RFC meant for
>> achieving consensus on what the bus nodes should look like, not an
>> actual patch meant to be taken. I was hoping I was clear on that, but I
>> guess that paragraph was buried too deep. Well...
>>> Plus simple bus within MMIO node needs unit address. IOW, don't mix MMIO
>>> with non-MMIO. I also suspect this does not pass checks, so the tools
>>> can do our review...
>> This DT passes "make dtbs_check" fine, with only unrelated warnings on
>> sec_uart1 that was already there before:
>>
>>   DTC [C] arch/riscv/boot/dts/spacemit/k1-bananapi-f3.dtb
>> .../arch/riscv/boot/dts/spacemit/k1-bananapi-f3.dtb: serial@...12000
>> (spacemit,k1-uart): 'clock-names' is a required property
>>         from schema $id: http://devicetree.org/schemas/serial/8250.yaml#
>>   DTC [C] arch/riscv/boot/dts/spacemit/k1-milkv-jupiter.dtb
>> .../arch/riscv/boot/dts/spacemit/k1-milkv-jupiter.dtb: serial@...12000
>> (spacemit,k1-uart): 'clock-names' is a required property
>>         from schema $id: http://devicetree.org/schemas/serial/8250.yaml#
>>
>> To be honest, I don't understand what "within MMIO node" means here.
>> Should the buses be taken out of /soc and added as its siblings?
> These looks like children of simple-bus. If that's right: children of
> simple-bus are supposed to have unit addresses (see also simple-bus in
> the DT schema).

The history of the simple-bus.yaml bindings file suggests that a
simple-bus with empty ranges and no unit address as a child of a parent
simple-bus is intentionally allowed [1]. The commit message also
suggests that even in older versions of the same file it was not the
intention to disallow such nested buses.

[1]: https://github.com/devicetree-org/dt-schema/commit/ed9190d20f146d13e262cc9138506326f7d4da91

Regards,
Vivian "dramforever" Wang