@@ -10,36 +10,24 @@
TODO
====
-CRC API Improvements
---------------------
-
-- Optimize CRC computation ``compute_crc()`` and plane blending ``blend()``
-
-- Use the alpha value to blend vaddr_src with vaddr_dst instead of
- overwriting it in ``blend()``.
-
-- 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).
+If you want to do any of the items listed below, please share your interest
+with one of the VKMS maintainers.
-- Configure planes/crtcs/connectors (we'd need some code to have more than 1 of
- them first).
+IGT better support
+------------------
-- Change output configuration: Plug/unplug screens, change EDID, allow changing
- the refresh rate.
+- 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.
-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
------------------
@@ -55,34 +43,50 @@ 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.
+
+Prime Buffer Sharing
+--------------------
-For all of these, we also want to review the igt test coverage and make sure all
-relevant igt testcases work on vkms.
+- Syzbot report:
+ WARNING in vkms_gem_free_object: https://lkml.org/lkml/2019/10/13/220
+
+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
-----------------
-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:
+- 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.
-- Writeback connector. This is useful for testing compositors if you don't have
- hardware with writeback support.
+- 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.
-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.
-
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
-----------------------
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/ 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> --- Documentation/gpu/vkms.rst | 99 ++++++++++++++++++++------------------ 1 file changed, 53 insertions(+), 46 deletions(-)