Commit cd252356 authored Feb 16, 2017 by Gabriel Krisman Bertazi Committed by Daniel Vetter Feb 26, 2017

drm: Always prepare null framebuffer in transitional helper

Despite the documentation claim that cleanup_fb will match prior calls
to prepare_fb, in case of NULL framebuffers in the transitional helpers,
the code will skip the call to prepare_fb but not the corresponding
cleanup_fb call. This asymmetry in semantics is unnecessarily surprising
for developers transitioning drivers to atomic model, specially because
the final atomic handlers don't have the issue - the prepare_fb is
always called, despite the new state framebuffer being null.

The only current user of the transitional helper that doesn't take care
of null framebuffers explicitly inside the prepare_fb hook is
atmel_hlcdc, so we take special care to make sure we don't break
anything there.

Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20170216164442.28704-1-krisman@collabora.co.uk

parent 3c6d6e0f

drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_plane.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -772,6 +772,9 @@ static int atmel_hlcdc_plane_prepare_fb(struct drm_plane *p,
		drm_plane_state_to_atmel_hlcdc_plane_state(s);
		int ret;

		if (!new_state->fb)
		return 0;

		ret = atmel_hlcdc_layer_update_start(&plane->layer);
		if (!ret)
		state->prepared = true;

drivers/gpu/drm/drm_plane_helper.c

+1 −2

Original line number	Diff line number	Diff line
		@@ -450,8 +450,7 @@ int drm_plane_helper_commit(struct drm_plane *plane,
		goto out;
		}

		if (plane_funcs->prepare_fb && plane_state->fb &&
		plane_state->fb != old_fb) {
		if (plane_funcs->prepare_fb && plane_state->fb != old_fb) {
		ret = plane_funcs->prepare_fb(plane,
		plane_state);
		if (ret)

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