Re: [Xen-devel][PATCH v5 0/1] cameraif: add ABI for para-virtual camera

[Oleksandr Andrushchenko <andr2000@gmail.com>]

Hello, Hans!

This is the version of the protocol with minor comments addressed
(that you had on v4). Hope this now looks OK.

Thank you,
Oleksandr

On 3/12/19 10:19 AM, Oleksandr Andrushchenko wrote:
> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
>
> Hello!
>
> At the moment Xen [1] already supports some virtual multimedia
> features [2] such as virtual display, sound. It supports keyboards,
> pointers and multi-touch devices all allowing Xen to be used in
> automotive appliances, In-Vehicle Infotainment (IVI) systems
> and many more.
>
> Frontend implementation is available at [3] and the corresponding
> backend at [4]. These are work in progress, but frontend already
> passes v4l2-compliance test for V4L2 drivers. libxl preliminary
> changes are available at [5].
>
> This work adds a new Xen para-virtualized protocol for a virtual
> camera device which extends multimedia capabilities of Xen even
> farther: video conferencing, IVI, high definition maps etc.
>
> The initial goal is to support most needed functionality with the
> final idea to make it possible to extend the protocol if need be:
>
> 1. Provide means for base virtual device configuration:
>   - pixel formats
>   - resolutions
>   - frame rates
> 2. Support basic camera controls:
>   - contrast
>   - brightness
>   - hue
>   - saturation
> 3. Support streaming control
>
> I would like to thank Hans Verkuil <hverkuil@xs4all.nl> for valuable
> comments and help.
>
> Thank you,
> Oleksandr Andrushchenko
>
> Changes since v4:
> =================
>
> 1. Removed unused XENCAMERA_EVT_CFG_FLG_RESOL flag
> 2. Re-worded a bit description for num_buffers
>
> Changes since v3:
> =================
>
> 1. Add trimming example for short FOURCC labels, e.g. Y16 and Y16-BE
> 2. Remove from XENCAMERA_OP_CONFIG_XXX requests colorspace, xfer_func,
>     ycbcr_enc, quantization and move those into the corresponding response
> 3. Extend description of XENCAMERA_OP_BUF_REQUEST.num_bufs: limit to
>     maximum buffers and num_bufs == 0 case
> 4. Extend decription of XENCAMERA_OP_BUF_CREATE.index and specify its
>     range
> 5. Make XENCAMERA_EVT_FRAME_AVAIL.seq_num 32-bit instead of 64-bit
>
> Changes since v2:
> =================
>
> 1. Add "max-buffers" frontend configuration entry, e.g.
>     the maximum number of camera buffers a frontend may use.
> 2. Add big-endian pixel-format support:
>   - "formats" configuration string length changed from 4 to 7
>     octets, so we can also manage BE pixel-formats
>   - add corresponding comments to FOURCC mappings description
> 3. New commands added to the protocol and documented:
>   - XENCAMERA_OP_CONFIG_VALIDATE
>   - XENCAMERA_OP_FRAME_RATE_SET
>   - XENCAMERA_OP_BUF_GET_LAYOUT
> 4.-Add defaults for colorspace, xfer, ycbcr_enc and quantization
> 5. Remove XENCAMERA_EVT_CONFIG_CHANGE event
> 6. Move plane offsets to XENCAMERA_OP_BUF_REQUEST as offsets
>     required for the frontend might not be known at the configuration time
> 7. Clean up and address comments to v2 of the protocol
>
> Changes since v1:
> =================
>
> 1. Added XenStore entries:
>   - frame-rates
> 2. Do not require the FOURCC code in XenStore to be upper case only
> 3. Added/changed command set:
>   - configuration get/set
>   - buffer queue/dequeue
>   - control get
> 4. Added control flags, e.g. read-only etc.
> 5. Added colorspace configuration support, relevant constants
> 6. Added events:
>   - configuration change
>   - control change
> 7. Changed control values to 64-bit
> 8. Added sequence number to frame avail event
> 9. Coding style cleanup
>
> [1] https://www.xenproject.org/
> [2] https://xenbits.xen.org/gitweb/?p=xen.git;a=tree;f=xen/include/public/io
> [3] https://github.com/andr2000/linux/tree/camera_front_v1/drivers/media/xen
> [4] https://github.com/andr2000/camera_be
> [5] https://github.com/andr2000/xen/tree/vcamera
>
>
> Oleksandr Andrushchenko (1):
>    cameraif: add ABI for para-virtual camera
>
>   xen/include/public/io/cameraif.h | 1370 ++++++++++++++++++++++++++++++
>   1 file changed, 1370 insertions(+)
>   create mode 100644 xen/include/public/io/cameraif.h
>