On Fri, Dec 05, 2025 at 04:21:07PM -0600, Bjorn Andersson wrote:
> On Mon, Nov 24, 2025 at 08:55:38PM +0530, Mukesh Ojha wrote:
> > On Mon, Nov 24, 2025 at 12:48:31PM +0100, Konrad Dybcio wrote:
> > > On 11/21/25 12:01 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 <[email protected]>
> > > > ---
> > > 
> > > [...]
> > > 
> > > > +int qcom_scm_pas_get_rsc_table(struct qcom_scm_pas_context *ctx, void 
> > > > *input_rt,
> > > > +                              size_t input_rt_size, void **output_rt,
> > > > +                              size_t *output_rt_size)
> > > > +{
> > > > +       unsigned int retry_num = 5;
> > > > +       int ret;
> > > > +
> > > > +       do {
> > > > +               *output_rt = kzalloc(*output_rt_size, GFP_KERNEL);
> > > > +               if (!*output_rt)
> > > > +                       return -ENOMEM;
> > > > +
> > > > +               ret = __qcom_scm_pas_get_rsc_table(ctx->pas_id, 
> > > > input_rt,
> > > > +                                                  input_rt_size, 
> > > > output_rt,
> > > > +                                                  output_rt_size);
> > > > +               if (ret)
> > > > +                       kfree(*output_rt);
> > > > +
> > > > +       } while (ret == -EAGAIN && --retry_num);
> > > 
> > > Will firmware return -EAGAIN as a result, or is this to handle the
> > > "buffer too small case"?
> > 
> > The latter one where a re-attempt could pass..
> > 
> 
> But why would we need more than 1 retry here? In what cases do we expect
> that the first attempt is too small, and then the next 4 attempts are
> also going to be too small?
> 
> Why is 5 a good number?

This was a misunderstanding, will fix it as per latest discussion.

-- 
-Mukesh Ojha

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