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.varba...@linaro.org>
> >> ---
> >> .../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.
> 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.
So, on 8916 I think you should use the form:
venus_mem: venus {
size = <0x500000>;
};
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.
Regards,
Bjorn
