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

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Message-ID: <axciimb7k4xktkliwrutn6ltcownbzz677bq7xbpybijfgrvrs@poy47oerxzop>
Date: Fri, 21 Nov 2025 14:07:50 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Ekansh Gupta <ekansh.gupta@....qualcomm.com>
Cc: 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>, 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 Thu, Nov 20, 2025 at 10:25:13AM +0530, Ekansh Gupta wrote:
> 
> 
> 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

Is it true for msm8916?

> 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

-- 
With best wishes
Dmitry