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? Regards, Bjorn > > > > I think the latter should use a different errno (EOVERFLOW?) and print > > a message since we decided that it's the caller that suggests a suitable > > output buffer size > > Agree with error code.. > > This is kept on the caller side keeping future in mind. where we can have > resource table coming from the client and it needs to go to TZ for > authentication. > > Are you suggesting to move this retry on the caller side ? > > Just for information, once video patches becomes ready, we may bring this > qcom_mdt_pas_map_devmem_rscs()[1] helper for video or any other client > should be do this here as well ? > > I wanted to optimize this path, where caller is making a guess and > gets the updated output size in return. > > [1] > https://lore.kernel.org/lkml/[email protected]/#t > > > > > In case it doesn't make sense for the caller to share their expectations, > > the buffer could be allocated (and perhaps resized if necessary) internally > > with some validation (i.e. a rsctable likely won't be 5 GiB) > > Are you saying output_size as well should be checked and it should not be > greater than something like UINT_MAX or something.. ? > > + *output_rt_size = res.result[2]; > > > > > > Konrad > > -- > -Mukesh Ojha
