Before re-using a VkCommandBuffer, we need to wait for its
operations to complete. Right now we unconditionally wait for
rendering to complete in vulkan_end(), however we have plans to
fix this [1]. To fully avoid blocking, we need to handle multiple
command buffers in flight at the same time (e.g. for multi-output,
or for rendering followed by texture uploads).
Implement a pool of command buffers. When we need to render, we
pick a command buffer from the pool which has completed its
operations. If we don't find one, try to allocate a new command
buffer. If we don't have slots in the pool anymore, block like we
did before.
[1]: https://gitlab.freedesktop.org/wlroots/wlroots/-/merge_requests/3574
Up until now we were using a VkFence for GPU-to-CPU
synchronization. This has some limitations that become a blocker
when trying to have multiple command buffers in flight at once
(e.g. for multi-output). It's desirable to implement a command
buffer pool [1], but VkFence cannot be used to track command buffer
completion for individual subpasses.
Let's just switch to timeline semaphores [2], which fix this issue,
make synchronization a lot more ergonomic and are a core Vulkan 1.2
feature.
[1]: https://gitlab.freedesktop.org/wlroots/wlroots/-/merge_requests/3802
[2]: https://www.khronos.org/blog/vulkan-timeline-semaphores
Added wlr_vk_renderer_get_* functions to allow get the VkInstance,
VkPhysicalDevice, VkDevice, queue family of a wlr_vk_renderer.
Added wlr_vk_renderer_get_current_image_attribs function to allow get
the VkImage of current renderer buffer to use on compositors.
Added wlr_renderer_is_vk function, it's like the wlr_renderer_is_gles2,
returns true if the wlr_renderer is a wlr_vk_renderer.
Added wlr_vk_image_get_attribs function to get a VkImage and it's
extras information (e.g. a VkImageLayout and VkImageFormat of the
VkImage) from a wlr_texture.
Instead of filling the fields one by one, use a struct initializer.
This avoids repeating the name of the variable and is more
consistent with the wlroots code style.
They are never used in practice, which makes all of our flag
handling effectively dead code. Also, APIs such as KMS don't
provide a good way to deal with the flags. Let's just fail the
DMA-BUF import when clients provide flags.
This new renderer is implemented with the existing wlr_renderer API
(which is known to be sub-optimal for some operations). It's not
used by default, but users can opt-in by setting WLR_RENDERER=vulkan.
The renderer depends on VK_EXT_image_drm_format_modifier and
VK_EXT_physical_device_drm.
Co-authored-by: Simon Ser <contact@emersion.fr>
Co-authored-by: Jan Beich <jbeich@FreeBSD.org>
