Message-ID: <975b468f-e5fc-40df-a9b6-2630f6ed99cc@mainlining.org>
Date: Fri, 21 Nov 2025 11:18:31 +0300
From: Nickolay Goppen <setotau@...nlining.org>
To: Ekansh Gupta <ekansh.gupta@....qualcomm.com>,
 Konrad Dybcio <konrad.dybcio@....qualcomm.com>,
 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


21.11.2025 11:11, Ekansh Gupta пишет:
>
> On 11/20/2025 5:17 PM, Konrad Dybcio wrote:
>> 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
> I don't think I can directly relate this property to unsigned PD offload. This is just
> defining what type of device node will be created and whether the channel is secure
> or not. There is a possibility of making unsigned PD request(on CDSP/GDSP) irrespective
> of whether this property is added or not. If DSP does not support unsigned offload, it
> should return failures for such requests.
>>> a more definitive recommendation once I know the specific use cases
>>> you plan to run.
>> Why would the usecase affect this?
> I'm saying this as per past discussions where some application was relying on non-secure
> device node on some old platform(on postmarketOS)[1] and having this property in place.
> So if similar usecase is being enabled here, the property might be required[1].

I'm testing these changes on postmarketOS. However, sensors aren't 
working through FastRPC on sdm660.

Is it better to leave this property for both nodes?

> [1] https://lkml.org/lkml/2024/8/15/117
>> Konrad

-- 
Best regards,
Nickolay

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