linux-kernel - Re: [PATCH v9 11/14] firmware: qcom_scm: Add qcom_scm_pas_get_rsc

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Message-ID: <20251218162820.fkhxc7nr7xcye57m@hu-mojha-hyd.qualcomm.com>
Date: Thu, 18 Dec 2025 21:58:20 +0530
From: Mukesh Ojha <mukesh.ojha@....qualcomm.com>
To: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
Cc: Bjorn Andersson <andersson@...nel.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Manivannan Sadhasivam <mani@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>, linux-arm-msm@...r.kernel.org,
        linux-remoteproc@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v9 11/14] firmware: qcom_scm: Add
 qcom_scm_pas_get_rsc_table() to get resource table

On Thu, Dec 18, 2025 at 02:34:27PM +0100, Konrad Dybcio wrote:
> On 12/17/25 5:34 PM, Mukesh Ojha wrote:
> > Qualcomm remote processor may rely on Static and Dynamic resources for
> > it to be functional. Static resources are fixed like for example,
> > memory-mapped addresses required by the subsystem and dynamic
> > resources, such as shared memory in DDR etc., are determined at
> > runtime during the boot process.
> > 
> > For most of the Qualcomm SoCs, when run with Gunyah or older QHEE
> > hypervisor, all the resources whether it is static or dynamic, is
> > managed by the hypervisor. Dynamic resources if it is present for a
> > remote processor will always be coming from secure world via SMC call
> > while static resources may be present in remote processor firmware
> > binary or it may be coming qcom_scm_pas_get_rsc_table() SMC call along
> > with dynamic resources.
> > 
> > Some of the remote processor drivers, such as video, GPU, IPA, etc., do
> > not check whether resources are present in their remote processor
> > firmware binary. In such cases, the caller of this function should set
> > input_rt and input_rt_size as NULL and zero respectively. Remoteproc
> > framework has method to check whether firmware binary contain resources
> > or not and they should be pass resource table pointer to input_rt and
> > resource table size to input_rt_size and this will be forwarded to
> > TrustZone for authentication. TrustZone will then append the dynamic
> > resources and return the complete resource table in output_rt
> > 
> > More about documentation on resource table format can be found in
> > include/linux/remoteproc.h
> > 
> > Signed-off-by: Mukesh Ojha <mukesh.ojha@....qualcomm.com>
> > ---
> 
> [...]
> 
> > +	memcpy(input_rt_tzm, input_rt, input_rt_size);
> > +
> > +	do {
> > +		output_rt_tzm = qcom_tzmem_alloc(__scm->mempool, size, GFP_KERNEL);
> > +		if (!output_rt_tzm) {
> > +			ret = -ENOMEM;
> > +			goto free_input_rt;
> > +		}
> > +
> > +		ret = __qcom_scm_pas_get_rsc_table(ctx->pas_id, input_rt_tzm,
> > +						   input_rt_size, output_rt_tzm,
> > +						   &size);
> > +		if (ret)
> > +			qcom_tzmem_free(output_rt_tzm);
> > +
> > +	} while (ret == -EOVERFLOW);
> 
> This still looks shaky (do-while is convenient for calling this twice, but perhaps
> the allocation could be moved to __qcom_scm_pas_get_rsc_table() since it's static
> anyway, and then we can just do:
> 
> ret = __qcom_scm_pas_get_rsc_table(...)
> if (ret == -EOVERFLOW) {
> 	/* Try again with the size requested by the TZ */
> 	ret = __qcom_scm_pas_get_rsc_table(...)
> }

Nice, Thanks., will apply.,

> 
> Other than that, it looks good (although there's still a lot of boilerplate
> that we can't really get rid of with C)
> 
> Konrad

-- 
-Mukesh Ojha