On Fri, Jan 22, 2021 at 10:27 AM Viresh Kumar viresh.kumar@linaro.org wrote:
On 15-01-21, 14:16, Arnd Bergmann via Stratos-dev wrote:
I don't think copying their properties to manifest adds any real value here. We should do that part over DT itself, as the guest is going to receive one from the host anyway. We just need to see how we divide this information between DT and manifests, or maybe we can make greybus work with DT as well (at the client side).
The thing is that if you need DT to describe greybus devices, you lose a lot of the benefits that greybus is meant to provide (independence of firmware interface, runtime hotplugging, aggregating multiple low-level devices into a functional unit, ...), but still have the added complexity of going through another software layer.
There is still the possible benefit of multiplexing several devices over a single virtio connection, e.g. a gpio controller, i2c controller, and spi controller could all share a single virtqueue, but I think we can achieve the same using simpler ways by building on normal virtio devices first and then adding in some form of multiplexing.
In yesterday's meeting, we briefly discussed rpmsg based serial devices without the extra greybus layer, which would be one alternative that also adds similar multiplexing, but also has similar problems with complexity.
Arnd