Hi, Cc: Marek On 08/30/2016 08:17 PM, Bjorn Andersson wrote: > On Mon 29 Aug 04:48 PDT 2016, Stanimir Varbanov wrote: > > [..] >>> Trying to wrap my head around how the iommu part works here. The >>> downstream code seems to indicate that this is a "generic" secure iommu >>> interface - used by venus, camera and kgsl; likely for dealing with DRM >>> protected buffers. >> >> The secure iommu interface is for content protected buffers. But these >> secure iommu contexts aren't used by msm DRM nor Venus in mainline. In >> Venus case I use non-secure iommu context for data buffers. >> > > We must consider the case when DRM, VFE and Venus handles protected > buffers. That would be interesting topic. > >>> >>> As such the iommu tables are not part of the venus rproc; I believe they >>> should either be tied into the msm-iommu driver or perhaps exposed as >>> its own iommu(?). >> >> The page tables are in msm-iommu driver. >> > > So, just to verify your answer, the msm-iommu driver will handle both > protected and unprotected? yes, at least for Venus case, the secured buffers are tied to different iommu contexts (and stream IDs). But this needs to be verified more carefully. > >>> >>> >>> But I presume from your inclusion that you've concluded that the venus >>> firmware we have refuses to execute without these tables at least >>> initialized, is this correct? >> >> Yes, the SMC call for PAS memory-setup will fail if this page table is >> not initialized. >> > > If the msm-iommu driver will handle the protected buffers (or if there > will be a separate iommu driver for protected buffers) it should issue > these calls, to not be dependant on the rproc-venus driver. For msm8916 we don't have iommu driver in mainline, I don't know what is the status with msm8996. > > With that I think we should make the rproc-venus driver depend on this > being setup (even if this means creating a "dummy" driver for the > protected iommu handling for now). This sounds scary :) > >>> >>>>> >>>>>> The address is not really fixed, cause the firmware could support >>>>>> relocation. In this example I just picked up the next free memory region >>>>>> in memory-reserved from msm8916.dtsi. >>>>>> >>>>> >>>>> In 8974 we do have a physical region where it's expected to be loaded. >>>>> >>>>> So in line with upcoming remoteproc work we should support referencing a >>>>> reserved-memory node with either reg or size. >>>>> >>>>> In the case of spotting a "reg" we're currently better off using >>>>> ioremap. We're looking at getting the remoteproc core to deal with this >>>>> mess. >>>> >>>> You mean that remoteproc core will parse memory-region property? >>>> >>> >>> It has to, because it's a quite common scenario for remoteproc drivers >>> to either get its backing memory from a static region or be restricted >>> to part of system ram - properties that reserved-memory and >>> memory-region captures already. >> >> OK, I have no issues with that. My concern is the manual parsing of >> 'memory-region' and 'reg' properties in remoteproc core. >> >> So that idea is to have generic binding for rproc, that would be good. >> > > I do share your concerns here. But it's a recurring issue with > remoteproc drivers. > > [..] >>> But I presume we have the implementation issue of dma_alloc_coherent() >>> failing in either case with the 5MB size. I think we need to look into >> >> I'd be good to include Marek Szyprowski? At least he will know what >> design restrictions there are. >> > > Please do. The more I look at this the more I think we must use the > existing infrastructure for allocating "dma memory". Getting > dma_alloc_coherent() supporting non-power-of-2 memory regions would Just to be precise it should be dma_alloc_from_coherent(). Marek, what is your opinion on that, can we make dma_alloc_from_coherent able to allocate memory for sizes with bigger granularity. For your convenience here [1] is the mail thread. > allow us to use the existing infrastructure, for both fixed and > dynamically placed memory carveouts in remoteproc. [1] https://lkml.org/lkml/2016/8/19/570 -- regards, Stan -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
