output: add wlr_output_state.allow_artifacts

When starting up, the compositor might call wlr_output_set_mode()
with a mode which is already the current one. wlroots will detect
this and make the wlr_output_set_mode() call a no-op. During the
next wlr_output_commit() call, wlroots will perform an atomic
commit without the ALLOW_MODESET flag.

This is an issue, because some drivers need ALLOW_MODESET even if
the mode is the same. For instance, if the FB stride or modifier
changed, some drivers require a modeset.

Add a new flag "allow_artifacts" which is set when the compositor
calls mode-setting functions. Use this flag to figure out whether
we want to perform atomic commits with ALLOW_MODESET.

(The name "allow_artifacts" is picked because ALLOW_MODESET is a
misnomer, see [1].)

[1]: https://patchwork.freedesktop.org/patch/505107/

Closes: https://gitlab.freedesktop.org/wlroots/wlroots/-/issues/3499
This commit is contained in:
Simon Ser 2022-09-28 11:09:53 +02:00 committed by Simon Zeni
parent baf3fa27dc
commit a0345f2854
3 changed files with 7 additions and 2 deletions

View file

@ -79,6 +79,9 @@ enum wlr_output_state_mode_type {
*/
struct wlr_output_state {
uint32_t committed; // enum wlr_output_state_field
// Set to true to allow temporary visual artifacts (e.g. black screen) while
// the update is being applied
bool allow_artifacts;
pixman_region32_t damage; // output-buffer-local coordinates
bool enabled;
float scale;