This is implemented by a two-subpass rendering scheme; the first
subpass draws (and blends) onto a linear R16G16B16A16_SFLOAT buffer,
while the second subpass performs linear->srgb conversion, writing
onto the actual output buffer.
The Vulkan spec doesn't guarantee that the driver will wait for
implicitly synchronized client buffers before texturing from them.
radv happens to perform the wait, but anv doesn't.
Fix this by extracting implicit fences from DMA-BUFs, importing
them into Vulkan as a VkSemaphore objects, and make the render pass
wait on these VkSemaphores.
struct wlr_vk_format_props contains a mix of properties for shm
and dmabuf, and it's not immediately clear which fields are for
which kind of buffer. Use a nested struct to group the fields.
Right now the Vulkan renderer blocks until the frame is complete
after rendering. This is necessary because Vulkan doesn't
interoperate well with implicit sync we use everywhere else.
Use the new kernel API to import a sync_file into a DMA-BUF to
avoid blocking.
We need to wait for the pending command buffer to complete before
re-using stage buffers. Otherwise we'll overwrite the stage buffer
with new contents before the texture is fully uploaded.
We need to wait for any pending command buffer to complete before
we're able to fully destroy a struct wlr_vk_texture: the Vulkan
spec requires the VkDescriptorSet to be kept alive.
So far we've done this in vulkan_end(), after blocking until the
command buffer completes. We'll soon stop blocking, so move this
logic in get_command_buffer(), where we check which commands buffers
have completed in a non-blocking fashion.
vkCmdCopyBufferToImage requires that the buffer offset be a multiple
of the texel block size, which for single plane uncompressed formats
is the same as the number of bytes per pixel. This commit adds an
alignment parameter to vulkan_get_stage_span which ensures that the
provided span (and the sequence of image copy operations derived which
use it) have this alignment.
Allow to get whether has alpha channel of the VkImage, it can help an
optimization to disable blending when the texture doesn't have alpha.
Because the VkFormat isn't enough because it's always set to
VK_FORMAT_B8G8R8A8_SRGB or VK_FORMAT_R8G8B8A8_SRGB.
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
In wlroots we add comments near struct wl_list members to indicate
which type it's linked to. The Vulkan renderer had some comments
with mistakes, and some members without a comment.
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>
