On Thu 25 Aug 04:10 PDT 2016, Stanimir Varbanov wrote: > Hi Bjorn, > > On 08/25/2016 03:05 AM, Bjorn Andersson wrote: > > On Wed 24 Aug 08:36 PDT 2016, Stanimir Varbanov wrote: > > > >> Hi Rob, > >> > >> On 08/23/2016 08:32 PM, Rob Herring wrote: > >>> On Fri, Aug 19, 2016 at 06:53:19PM +0300, Stanimir Varbanov wrote: > >>>> Add devicetree binding document for Venus remote processor. > >>>> > >>>> Signed-off-by: Stanimir Varbanov <stanimir.varbanov@xxxxxxxxxx> > >>>> --- > >>>> .../devicetree/bindings/remoteproc/qcom,venus.txt | 33 ++++++++++++++++++++++ > >>>> 1 file changed, 33 insertions(+) > >>>> create mode 100644 Documentation/devicetree/bindings/remoteproc/qcom,venus.txt > >>>> > >>>> diff --git a/Documentation/devicetree/bindings/remoteproc/qcom,venus.txt b/Documentation/devicetree/bindings/remoteproc/qcom,venus.txt > >>>> new file mode 100644 > >>>> index 000000000000..06a2db60fa38 > >>>> --- /dev/null > >>>> +++ b/Documentation/devicetree/bindings/remoteproc/qcom,venus.txt > >>>> @@ -0,0 +1,33 @@ > >>>> +Qualcomm Venus Peripheral Image Loader > >>>> + > >>>> +This document defines the binding for a component that loads and boots firmware > >>>> +on the Qualcomm Venus remote processor core. > >>> > >>> This does not make sense to me. Venus is the video encoder/decoder h/w, > >>> right? Why is the firmware loader separate from the codec block? Why > >>> rproc is used? Are there multiple clients? Naming it rproc_venus implies > >>> there aren't. And why does the firmware loading need 8MB of memory at a > >>> fixed address? > >>> > >> > >> The firmware for Venus case is 5MB. And here is 8MB because of > >> dma_alloc_from_coherent size restriction. > >> > > > > Then you should specify it 5MB large and we'll have to deal with this > > implementation issue in the code. I've created a JIRA ticket for > > the dma_alloc_from_coherent() behavior. > > Infact it should be 5MB + ~100KB for iommu page table. > 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. 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(?). 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? > > > >> 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. > > > > > > So, on 8916 I think you should use the form: > > > > venus_mem: venus { > > size = <0x500000>; > > }; > > Don't forget that the physical address where the firmware is stored has > some range, the scm call will fail if it is out of the expected range, > probably because of some security reasons. So maybe alloc-ranges should > be specified here. > Thanks for highlighting this. > > > > And I don't think you should use the shared-dma-pool compatible, because > > this is not a region for multiple devices to allocate dma memory out of. > > Then I cannot reuse reserved-mem infrastructure. > You're right. If I understand the code correctly we need to use the compatible shared-dma-pool and mark it either "no-map" or "reusable", to be able to use dma_alloc_coherent(). 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 that - and have created a JIRA ticket for it. Regards, Bjorn -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html