On Wed, Aug 20, 2025 at 10:12:15AM +0200, Stephan Gerhold wrote: > On Tue, Aug 19, 2025 at 10:24:41PM +0530, Mukesh Ojha wrote: > > The resource table data structure has traditionally been associated with > > the remoteproc framework, where the resource table is included as a > > section within the remote processor firmware binary. However, it is also > > possible to obtain the resource table through other means—such as from a > > reserved memory region populated by the boot firmware, statically > > maintained driver data, or via a secure SMC call—when it is not embedded > > in the firmware. > > > > There are multiple Qualcomm remote processors (e.g., Venus, Iris, GPU, > > etc.) in the upstream kernel that do not use the remoteproc framework to > > manage their lifecycle for various reasons. > > > > When Linux is running at EL2, similar to the Qualcomm PAS driver > > (qcom_q6v5_pas.c), client drivers for subsystems like video and GPU may > > also want to use the resource table SMC call to retrieve and map > > resources before they are used by the remote processor. > > > > All the examples you give here (Venus/Iris, GPU) have some sort of EL2 > support already for older platforms:
Example was taken from perspective of remote processor life-cycle management. You are right they have worked before in non-secure way for Chrome. > > - For GPU, we just skip loading the ZAP shader and access the protected > registers directly. I would expect the ZAP shader does effectively > the same, perhaps with some additional handling for secure mode. Is > this even a real remote processor that has a separate IOMMU domain? > I don't think it is the case and think the same that they can skip loading and Hence, I have not yet added support for it. Will check internally before doing anything on GPU. > - For Venus/Iris, there is code upstream similar to your PATCH 11/11 > that maps the firmware with the IOMMU (but invokes reset directly > using the registers, without using PAS). There is no resource table > used for that either, so at least all Venus/Iris versions so far > apparently had no need for any mappings aside from the firmware > binary. You are absolutely right > > I understand that you want to continue using PAS for these, but I'm a > bit confused what kind of mappings we would expect to have in the > resource table for video and GPU. Could you give an example? We have some debug hw tracing available for video for lemans, which is optional However, I believe infra is good to have incase we need some required resources to be map for Video to work for a SoC. > > Thanks, > Stephan -- -Mukesh Ojha
