On Thu, May 05, 2016 at 03:24:33PM +0200, Noralf Trønnes wrote:
Provides helper functions for drivers that have a simple display pipeline. Plane, crtc and encoder are collapsed into one entity.
Signed-off-by: Noralf Trønnes noralf@tronnes.org
+static int drm_simple_kms_plane_atomic_check(struct drm_plane *plane,
struct drm_plane_state *pstate)+{
- struct drm_simple_display_pipe *pipe;
- struct drm_crtc_state *cstate;
- pipe = container_of(plane, struct drm_simple_display_pipe, plane);
- if (!pipe->funcs || !pipe->funcs->check)
return 0;- cstate = drm_atomic_get_existing_crtc_state(pstate->state,
&pipe->crtc);- return pipe->funcs->check(pipe, pstate, cstate);
+}
Ok one thing I've missed here is that for most drivers this is way too simple a check function, which means we'll end up with tons of duplicated code. Things which the drm core allows, but simple pipelines all don't really cope with: - plane scaling - disabling the plane without the crtc (i.e. scan out black) - plane not sized to fill the entire hactive/vactive
There's a helper to do most of these checks for you - drm_plane_helper_check_update. I think it'd be good to place a call for that in here, before we call down into the driver's ->check callback. But ofc before we return 0; we want these checks always done. And catch all these things so that drivers never fall over this pitfall.
Noticed while discussing tilcdc atomic patches, since tilcdc could probably use drm_simple_display_pipe too. -Daniel