linux-kernel - Re: [PATCH v2 1/3] arm64: dts: qcom: sdm630/660: Add CDSP-related nodes

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Message-ID: <99c22e73-797c-4a30-92ba-bc3bd8cf70f0@oss.qualcomm.com>
Date: Thu, 20 Nov 2025 10:25:13 +0530
From: Ekansh Gupta <ekansh.gupta@....qualcomm.com>
To: Srinivas Kandagatla <srinivas.kandagatla@....qualcomm.com>,
        Konrad Dybcio <konrad.dybcio@....qualcomm.com>,
        Nickolay Goppen <setotau@...nlining.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>, Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>
Cc: linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, ~postmarketos/upstreaming@...ts.sr.ht,
        linux@...nlining.org, Chenna Kesava Raju <chennak@....qualcomm.com>,
        Bharath Kumar <bkumar@....qualcomm.com>
Subject: Re: [PATCH v2 1/3] arm64: dts: qcom: sdm630/660: Add CDSP-related
 nodes



On 11/20/2025 1:58 AM, Srinivas Kandagatla wrote:
> On 11/12/25 1:52 PM, Konrad Dybcio wrote:
>> On 11/10/25 6:41 PM, Srinivas Kandagatla wrote:
>>> On 11/3/25 12:52 PM, Konrad Dybcio wrote:
>>>> On 10/31/25 12:30 PM, Nickolay Goppen wrote:
>>>>> 24.10.2025 16:58, Nickolay Goppen пишет:
>>>>>> 24.10.2025 11:28, Konrad Dybcio пишет:
>>>>>>> On 10/23/25 9:51 PM, Nickolay Goppen wrote:
>>>>>>>> In order to enable CDSP support for SDM660 SoC:
>>>>>>>>   * add shared memory p2p nodes for CDSP
>>>>>>>>   * add CDSP-specific smmu node
>>>>>>>>   * add CDSP peripheral image loader node
>>>>>>>>
>>>>>>>> Memory region for CDSP in SDM660 occupies the same spot as
>>>>>>>> TZ buffer mem defined in sdm630.dtsi (which does not have CDSP).
>>>>>>>> In sdm660.dtsi replace buffer_mem inherited from SDM630 with
>>>>>>>> cdsp_region, which is also larger in size.
>>>>>>>>
>>>>>>>> SDM636 also doesn't have CDSP, so remove inherited from sdm660.dtsi
>>>>>>>> related nodes and add buffer_mem back.
>>>>>>>>
>>>>>>>> Signed-off-by: Nickolay Goppen <setotau@...nlining.org>
>>>>>>>> ---
>>>>>>> [...]
>>>>>>>
>>>>>>>> +            label = "turing";
>>>>>>> "cdsp"
>>>>>> Ok, I'll change this in the next revision.
>>>>>>>> +            mboxes = <&apcs_glb 29>;
>>>>>>>> +            qcom,remote-pid = <5>;
>>>>>>>> +
>>>>>>>> +            fastrpc {
>>>>>>>> +                compatible = "qcom,fastrpc";
>>>>>>>> +                qcom,glink-channels = "fastrpcglink-apps-dsp";
>>>>>>>> +                label = "cdsp";
>>>>>>>> +                qcom,non-secure-domain;
>>>>>>> This shouldn't matter, both a secure and a non-secure device is
>>>>>>> created for CDSP
>>>>>> I've added this property, because it is used in other SoC's, such as SDM845 and SM6115 for both ADSP and CDSP
>>>>> Is this property not neccessary anymore?
>>>> +Srini?
>>> That is true, we do not require this for CDSP, as CDSP allows both
>>> unsigned and signed loading, we create both secured and non-secure node
>>> by default. May be we can provide that clarity in yaml bindings so that
>>> it gets caught during dtb checks.
>>>
>>>
>>> However in ADSP case, we only support singed modules, due to historical
>>> reasons how this driver evolved over years, we have this flag to allow
>>> compatiblity for such users.
>> Does that mean that we can only load signed modules on the ADSP, but
>> the driver behavior was previously such that unsigned modules were
>> allowed (which was presumably fine on devboards, but not on fused
>> devices)?
> Yes, its true that we allowed full access to adsp device nodes when we
> first started upstreaming fastrpc driver.
>
> irrespective of the board only signed modules are supported on the ADSP.
> I think there was one version of SoC i think 8016 or some older one
> which had adsp with hvx which can load unsigned modules for compute
> usecase only.
>
> I have added @Ekansh for more clarity.
>
> --srini

For all the available platforms, ADSP supports only signed modules. Unsigned
modules(as well as signed) are supported by CDSP and GDSP subsystems.

qcom,non-secure-domain property marks the corresponding DSP as non-secure DSP.
The implications of adding this property would be the following:
on ADSP, SDSP, MDSP:
- Only non-secure device node(/dev/fastrpc-Xdsp) is created.
- Non-secure device node can be used for signed DSP PD offload.

on CDSP, GDSP:
- Both secure(/dev/fastrpc-Xdsp-secure) and non-secure(/dev/fastrpc-Xdsp) devices
  are created, regardless of this property.
- Both the nodes can be used for signed and unsigned DSP PD offload.

Note: If the property is not added for CDSP/GDSP, only secure device node can
be used for signed PD offload, if non-secure device is used, the request gets
rejected[1].

[1] https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/drivers/misc/fastrpc.c#n1245

//Ekansh

>
>
>> Konrad