drm/vkms: update todo

Drop issues already resolved in vkms:

- CRC API Improvements to [1] add igt test to check extreme alpha values
  and [2] alpha blending;
- [3] prime buffer sharing;
- [4] writeback support;

On the other hand, we also found or thought about other improvements since
the last update of this document:

- better support for IGT tests
- improvements to writeback support
- syzbot report

Finally, we reorder items by the assumed complexity.

[1] https://patchwork.freedesktop.org/series/55944/
[2] https://patchwork.freedesktop.org/series/80823/
[3] https://patchwork.freedesktop.org/series/63212/
[4] https://patchwork.freedesktop.org/series/81177/

v2:
- Link to syzbot dashboard

Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
Cc: Haneen Mohammed <hamohammed.sa@gmail.com>

Signed-off-by: Melissa Wen <melissa.srw@gmail.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201006223006.gu55pjtuaigkh6il@smtp.gmail.com
This commit is contained in:
Melissa Wen 2020-10-06 19:30:06 -03:00
parent 955a341f33
commit 5a3884320a
1 changed files with 57 additions and 50 deletions

View File

@ -10,36 +10,24 @@
TODO
====
CRC API Improvements
--------------------
If you want to do any of the items listed below, please share your interest
with VKMS maintainers.
- Optimize CRC computation ``compute_crc()`` and plane blending ``blend()``
IGT better support
------------------
- Use the alpha value to blend vaddr_src with vaddr_dst instead of
overwriting it in ``blend()``.
- Investigate: (1) test cases on kms_plane that are failing due to timeout on
capturing CRC; (2) when running kms_flip test cases in sequence, some
successful individual test cases are failing randomly.
- Add igt test to check cleared alpha value for XRGB plane format.
- Add igt test to check extreme alpha values i.e. fully opaque and fully
transparent (intermediate values are affected by hw-specific rounding modes).
Runtime Configuration
---------------------
We want to be able to reconfigure vkms instance without having to reload the
module. Use/Test-cases:
- Hotplug/hotremove connectors on the fly (to be able to test DP MST handling of
compositors).
- Configure planes/crtcs/connectors (we'd need some code to have more than 1 of
them first).
- Change output configuration: Plug/unplug screens, change EDID, allow changing
the refresh rate.
The currently proposed solution is to expose vkms configuration through
configfs. All existing module options should be supported through configfs too.
- VKMS already has support for vblanks simulated via hrtimers, which can be
tested with kms_flip test; in some way, we can say that VKMS already mimics
the real hardware vblank. However, we also have virtual hardware that does
not support vblank interrupt and completes page_flip events right away; in
this case, compositor developers may end up creating a busy loop on virtual
hardware. It would be useful to support Virtual Hardware behavior in VKMS
because this can help compositor developers to test their features in
multiple scenarios.
Add Plane Features
------------------
@ -55,33 +43,49 @@ There's lots of plane features we could add support for:
- Additional buffer formats, especially YUV formats for video like NV12.
Low/high bpp RGB formats would also be interesting.
- Async updates (currently only possible on cursor plane using the legacy cursor
api).
- Async updates (currently only possible on cursor plane using the legacy
cursor api).
For all of these, we also want to review the igt test coverage and make sure all
relevant igt testcases work on vkms.
Writeback support
-----------------
Currently vkms only computes a CRC for each frame. Once we have additional plane
features, we could write back the entire composited frame, and expose it as:
- Writeback connector. This is useful for testing compositors if you don't have
hardware with writeback support.
- As a v4l device. This is useful for debugging compositors on special vkms
configurations, so that developers see what's really going on.
For all of these, we also want to review the igt test coverage and make sure
all relevant igt testcases work on vkms.
Prime Buffer Sharing
--------------------
We already have vgem, which is a gem driver for testing rendering, similar to
how vkms is for testing the modeset side. Adding buffer sharing support to vkms
allows us to test them together, to test synchronization and lots of other
features. Also, this allows compositors to test whether they work correctly on
SoC chips, where the display and rendering is very often split between 2
drivers.
- Syzbot report - WARNING in vkms_gem_free_object:
https://syzkaller.appspot.com/bug?extid=e7ad70d406e74d8fc9d0
Runtime Configuration
---------------------
We want to be able to reconfigure vkms instance without having to reload the
module. Use/Test-cases:
- Hotplug/hotremove connectors on the fly (to be able to test DP MST handling
of compositors).
- Configure planes/crtcs/connectors (we'd need some code to have more than 1 of
them first).
- Change output configuration: Plug/unplug screens, change EDID, allow changing
the refresh rate.
The currently proposed solution is to expose vkms configuration through
configfs. All existing module options should be supported through configfs
too.
Writeback support
-----------------
- The writeback and CRC capture operations share the use of composer_enabled
boolean to ensure vblanks. Probably, when these operations work together,
composer_enabled needs to refcounting the composer state to proper work.
- Add support for cloned writeback outputs and related test cases using a
cloned output in the IGT kms_writeback.
- As a v4l device. This is useful for debugging compositors on special vkms
configurations, so that developers see what's really going on.
Output Features
---------------
@ -93,7 +97,10 @@ Output Features
- Add support for link status, so that compositors can validate their runtime
fallbacks when e.g. a Display Port link goes bad.
- All the hotplug handling describe under "Runtime Configuration".
CRC API Improvements
--------------------
- Optimize CRC computation ``compute_crc()`` and plane blending ``blend()``
Atomic Check using eBPF
-----------------------