drm/omap: dynamically assign hw overlays to planes

(re)assign the hw overlays to planes based on required caps, and to
handle situations where we could not modify an in-use plane.

This means all planes advertise the superset of formats and properties.
Userspace must (as always) use atomic TEST_ONLY step for atomic updates,
as not all planes may be available for use on every frame.

The mapping of hwoverlays to plane is stored in omap_global_state, so
that state updates are atomically committed in the same way that
plane/etc state updates are managed.  This is needed because the
omap_plane_state keeps a pointer to the hwoverlay, and we don't want
global state to become out of sync with the plane state if an atomic
update fails, we hit deadlock/ backoff scenario, etc.  The use of
global_state_lock keeps multiple parallel updates which both re-assign
hwoverlays properly serialized.

Signed-off-by: Benoit Parrot <bparrot@ti.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211117141928.771082-8-narmstrong@baylibre.com

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/gpu/drm/omapdrm/omap_drv.h b/drivers/gpu/drm/omapdrm/omap_drv.h
index a3079aad7ae3..825960fd3ea9 100644
--- a/drivers/gpu/drm/omapdrm/omap_drv.h
+++ b/drivers/gpu/drm/omapdrm/omap_drv.h
@@ -50,6 +50,9 @@ struct omap_drm_pipeline {
 
 struct omap_global_state {
 	struct drm_private_state base;
+
+	/* global atomic state of assignment between overlays and planes */
+	struct drm_plane *hwoverlay_to_plane[8];
 };
 
 struct omap_drm_private {