Message-ID: <24221ce7-24e4-4eaa-8681-ed9b4b9f2d6e@oss.qualcomm.com>
Date: Thu, 20 Nov 2025 12:47:50 +0100
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: Ekansh Gupta <ekansh.gupta@....qualcomm.com>,
        Nickolay Goppen <setotau@...nlining.org>,
        Srinivas Kandagatla <srinivas.kandagatla@....qualcomm.com>,
        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 11/20/25 11:54 AM, Ekansh Gupta wrote:
> 
> 
> On 11/20/2025 1:27 PM, Nickolay Goppen wrote:
>>
>> 20.11.2025 07:55, Ekansh Gupta пишет:
>>>
>>> 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
>> Does this mean that the qcom,non-secure-domain property should be dropped from both nodes? 
> I checked again and found that unsigned module support for CDSP is
> not available on this platform. Given this, the safest approach would
> be to add the property for both ADSP and CDSP, ensuring that all
> created device nodes can be used for signed PD offload. I can provide

The property allows *unsigned* PD offload though

> a more definitive recommendation once I know the specific use cases
> you plan to run.

Why would the usecase affect this?

Konrad

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