Hi, This is the 8th version of virtio-video device patch. Feedback would be very appreciated. The main change coming with this draft is the introduction of background operations and delayed responses to commands (the term is taken from the SCMI spec) over eventq. Now most of the commands work like this. The only exceptions are STREAM_CREATE and RESOURCE_ATTACH_BACKING commands. This should help avoid commandq descriptors exhaustion. Also I introduced "in band" and "out of band" handling of SET_PARAMS command. Out of band is the way how it was done before i.e. the command is handled immediately after dequeuing from commandq. In band means putting it into device's INPUT queue so that it can be executed precisely after a certain input resource and before the next one. These two changes allowed me to represent the events as a custom case of the delayed responses. Also this enables processing resolution changes embedded in the stream and coming from outside in the same way. I think this makes it possible to implement V4L2 Requests API. Questions for discussion/roadmap: 1. It looks like the current way of describing the device capabilities is not very well extendable. I'd like to change it again. The goal is that after adding new generic parameters/new codecs/new codec parameters and covering them with the feature flags the format of the device response doesn't depend that much on the enabled flags. My current idea is to convert this into a serie of descriptors with offsets and sizes, so that the device can then simply adjust offsets and sizes, but keep that layout the same. Any ideas here would be appreciated. 2. Since draft v7 the device is expected to provide all and every one of its capabilities as a response to the DEVICE_QUERY_CAPS command. Maybe the device shouldn't adjust the parameters itself now? 3. I think the last piece, that is missing completely, is QoS. How can the device indicate to the driver, that it is saturated? How could the device be shared between multiple guests in a fair way? Full PDF: https://drive.google.com/file/d/1uPg4kxThlNPBSiC4b5veyFz4OFGytU7v/view?usp=sharing PDF with the video section only: https://drive.google.com/file/d/1iW3MbseRZLovlxpc4XAF8VTvhQ_Tww6q/view?usp=sharing Changelog v7 -> v8: * Added the delayed responses to commands sent on the eventq. * Added the in band STREAM_SET_PARAMS command handling. * Implemented device events using the newly added delayed responses. Alexander Gordeev (1): virtio-video: Add virtio video device specification conformance.tex | 4 + content.tex | 1 + device-types/video/description.tex | 2040 +++++++++++++++++++++ device-types/video/device-conformance.tex | 22 + device-types/video/driver-conformance.tex | 16 + introduction.tex | 21 + 6 files changed, 2104 insertions(+) create mode 100644 device-types/video/description.tex create mode 100644 device-types/video/device-conformance.tex create mode 100644 device-types/video/driver-conformance.tex -- 2.34.1
