wayland-protocols

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Simon Ser 3683a5eb66 linux-dmabuf: clarify what mixed valid/INVALID modifiers mean This commit makes it clear that compositors can send valid modifiers and DRM_FORMAT_MOD_INVALID for a given format. This means that the compositor supports both implicit and explicit modifiers. See the warning further down: > Warning: It should be an error if the format/modifier pair was not > advertised with the modifier event. This is not enforced yet because > some implementations always accept DRM_FORMAT_MOD_INVALID. Also > version 2 of this protocol does not have the modifier event. Xwayland already requires compositors to send DRM_FORMAT_MOD_INVALID for importing buffers with an implicit modifier [1]. In a future protocol version, it would be nice to make it a protocol error (or at least a soft failure) to use any format/modifier pair that wasn't advertised. A use-case for this is Vulkan compositors: the Vulkan DMA-BUF extensions require an explicit modifier and cannot import buffers which have an implicit modifier. [1]: `6c51818a0f/hw/xwayland/xwayland-glamor-gbm.c (L328)` Signed-off-by: Simon Ser <contact@emersion.fr>	2021-03-31 07:24:53 +00:00
..
linux-dmabuf-unstable-v1.xml	linux-dmabuf: clarify what mixed valid/INVALID modifiers mean	2021-03-31 07:24:53 +00:00
README	Add README files containing protocol maintainers	2015-10-29 11:08:12 +08:00

Simon Ser 3683a5eb66 linux-dmabuf: clarify what mixed valid/INVALID modifiers mean

This commit makes it clear that compositors can send valid modifiers and
DRM_FORMAT_MOD_INVALID for a given format. This means that the compositor
supports both implicit and explicit modifiers. See the warning further
down:

> Warning: It should be an error if the format/modifier pair was not
> advertised with the modifier event. This is not enforced yet because
> some implementations always accept DRM_FORMAT_MOD_INVALID. Also
> version 2 of this protocol does not have the modifier event.

Xwayland already requires compositors to send DRM_FORMAT_MOD_INVALID
for importing buffers with an implicit modifier [1].

In a future protocol version, it would be nice to make it a protocol
error (or at least a soft failure) to use any format/modifier pair that
wasn't advertised. A use-case for this is Vulkan compositors: the Vulkan
DMA-BUF extensions require an explicit modifier and cannot import
buffers which have an implicit modifier.

[1]: 6c51818a0f/hw/xwayland/xwayland-glamor-gbm.c (L328)

Signed-off-by: Simon Ser <contact@emersion.fr>

2021-03-31 07:24:53 +00:00

linux-dmabuf-unstable-v1.xml linux-dmabuf: clarify what mixed valid/INVALID modifiers mean 2021-03-31 07:24:53 +00:00

README Add README files containing protocol maintainers 2015-10-29 11:08:12 +08:00

README

Linux DMA-BUF protocol

Maintainers:
Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Daniel Stone <daniels@collabora.com>