[PATCH weston v6 68/73] compositor-drm: head detach requires a modeset

[Pekka Paalanen]

From: Pekka Paalanen <pekka.paalanen at collabora.co.uk>

When a head is detached from an enabled output, that output needs to go
through a modeset (drmModeSetCrtc() / ATOMIC_ALLOW_MODESET) so that the
connector is actually removed from the CRTC.

This has not yet been a problem, because an output could only have one
head at a time, and would be automatically disabled on detach. It would
be a problem with clone mode.

Signed-off-by: Pekka Paalanen <pekka.paalanen at collabora.co.uk>
---
 libweston/compositor-drm.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/libweston/compositor-drm.c b/libweston/compositor-drm.c
index 82f014d7..d1fc66ac 100644
--- a/libweston/compositor-drm.c
+++ b/libweston/compositor-drm.c
@@ -4410,6 +4410,23 @@ drm_output_attach_head(struct weston_output *output_base,
 	return 0;
 }
 
+static void
+drm_output_detach_head(struct weston_output *output_base,
+		       struct weston_head *head_base)
+{
+	struct drm_backend *b = to_drm_backend(output_base->compositor);
+
+	if (!output_base->enabled)
+		return;
+
+	/* Need to go through modeset to drop connectors that should no longer
+	 * be driven. */
+	/* XXX: Ideally we'd do this per-output, not globally. */
+	b->state_invalid = true;
+
+	weston_output_schedule_repaint(output_base);
+}
+
 static int
 parse_gbm_format(const char *s, uint32_t default_value, uint32_t *gbm_format)
 {
@@ -5423,6 +5440,7 @@ drm_output_create(struct weston_compositor *compositor, const char *name)
 	output->base.destroy = drm_output_destroy;
 	output->base.disable = drm_output_disable;
 	output->base.attach_head = drm_output_attach_head;
+	output->base.detach_head = drm_output_detach_head;
 
 	output->destroy_pending = 0;
 	output->disable_pending = 0;
-- 
2.13.6