Message-ID: <iwtasncd3wu73xv4ot5sl5zjukhqzxo2m4s4aeetj2ylrke7b3@47trnxo2lcci>
Date: Fri, 21 Nov 2025 14:11:42 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Nickolay Goppen <setotau@...nlining.org>
Cc: 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>, 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 Fri, Nov 21, 2025 at 11:18:31AM +0300, Nickolay Goppen wrote:
> 
> 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.

How? Could you mention, what exactly doesn't work?

> 
> Is it better to leave this property for both nodes?
> 
> > [1] https://lkml.org/lkml/2024/8/15/117
> > > Konrad
> 
> -- 
> Best regards,
> Nickolay
> 

-- 
With best wishes
Dmitry

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