drm/vc4: Rework the async update logic

vc4_plane_atomic_async_check() was only based on the
state->{crtc,src}_{w,h} which was fine since scaling was not allowed on
the cursor plane.

We are about to change that to properly support underscan, and, in order
to make the async check more reliable, we call vc4_plane_mode_set()
from there and check that only the pos0, pos2 and ptr0 entries in the
dlist have changed.

In vc4_plane_atomic_async_update(), we no longer call
vc4_plane_atomic_check() since vc4_plane_mode_set() has already been
called in vc4_plane_atomic_async_check(), and we don't need to allocate
a new LBM region (we reuse the one from the current state).

Note that we now have to manually update each field of the current
plane state since it's no longer updated in place (not sure we have
to sync all of them, but it's harmless if we do).
We also drop the vc4_plane_async_set_fb() call (ptr0 dlist entry has
been properly updated in vc4_plane_mode_set())

Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20181130090254.594-4-boris.brezillon@bootlin.com

drivers/gpu/drm/vc4/vc4_plane.c

@@ -895,30 +895,50 @@ static void vc4_plane_atomic_async_update(struct drm_plane *plane,
 {
 	struct vc4_plane_state *vc4_state, *new_vc4_state;
 
-	if (plane->state->fb != state->fb) {
-		vc4_plane_async_set_fb(plane, state->fb);
-		drm_atomic_set_fb_for_plane(plane->state, state->fb);
-	}
-
-	/* Set the cursor's position on the screen.  This is the
-	 * expected change from the drm_mode_cursor_universal()
-	 * helper.
-	 */
+	drm_atomic_set_fb_for_plane(plane->state, state->fb);
 	plane->state->crtc_x = state->crtc_x;
 	plane->state->crtc_y = state->crtc_y;
-
-	/* Allow changing the start position within the cursor BO, if
-	 * that matters.
-	 */
+	plane->state->crtc_w = state->crtc_w;
+	plane->state->crtc_h = state->crtc_h;
 	plane->state->src_x = state->src_x;
 	plane->state->src_y = state->src_y;
-
-	/* Update the display list based on the new crtc_x/y. */
-	vc4_plane_atomic_check(plane, state);
+	plane->state->src_w = state->src_w;
+	plane->state->src_h = state->src_h;
+	plane->state->src_h = state->src_h;
+	plane->state->alpha = state->alpha;
+	plane->state->pixel_blend_mode = state->pixel_blend_mode;
+	plane->state->rotation = state->rotation;
+	plane->state->zpos = state->zpos;
+	plane->state->normalized_zpos = state->normalized_zpos;
+	plane->state->color_encoding = state->color_encoding;
+	plane->state->color_range = state->color_range;
+	plane->state->src = state->src;
+	plane->state->dst = state->dst;
+	plane->state->visible = state->visible;
 
 	new_vc4_state = to_vc4_plane_state(state);
 	vc4_state = to_vc4_plane_state(plane->state);
 
+	vc4_state->crtc_x = new_vc4_state->crtc_x;
+	vc4_state->crtc_y = new_vc4_state->crtc_y;
+	vc4_state->crtc_h = new_vc4_state->crtc_h;
+	vc4_state->crtc_w = new_vc4_state->crtc_w;
+	vc4_state->src_x = new_vc4_state->src_x;
+	vc4_state->src_y = new_vc4_state->src_y;
+	memcpy(vc4_state->src_w, new_vc4_state->src_w,
+	       sizeof(vc4_state->src_w));
+	memcpy(vc4_state->src_h, new_vc4_state->src_h,
+	       sizeof(vc4_state->src_h));
+	memcpy(vc4_state->x_scaling, new_vc4_state->x_scaling,
+	       sizeof(vc4_state->x_scaling));
+	memcpy(vc4_state->y_scaling, new_vc4_state->y_scaling,
+	       sizeof(vc4_state->y_scaling));
+	vc4_state->is_unity = new_vc4_state->is_unity;
+	vc4_state->is_yuv = new_vc4_state->is_yuv;
+	memcpy(vc4_state->offsets, new_vc4_state->offsets,
+	       sizeof(vc4_state->offsets));
+	vc4_state->needs_bg_fill = new_vc4_state->needs_bg_fill;
+
 	/* Update the current vc4_state pos0, pos2 and ptr0 dlist entries. */
 	vc4_state->dlist[vc4_state->pos0_offset] =
 		new_vc4_state->dlist[vc4_state->pos0_offset];
@@ -942,13 +962,38 @@ static void vc4_plane_atomic_async_update(struct drm_plane *plane,
 static int vc4_plane_atomic_async_check(struct drm_plane *plane,
 					struct drm_plane_state *state)
 {
-	/* No configuring new scaling in the fast path. */
-	if (plane->state->crtc_w != state->crtc_w ||
-	    plane->state->crtc_h != state->crtc_h ||
-	    plane->state->src_w != state->src_w ||
-	    plane->state->src_h != state->src_h)
+	struct vc4_plane_state *old_vc4_state, *new_vc4_state;
+	int ret;
+	u32 i;
+
+	ret = vc4_plane_mode_set(plane, state);
+	if (ret)
+		return ret;
+
+	old_vc4_state = to_vc4_plane_state(plane->state);
+	new_vc4_state = to_vc4_plane_state(state);
+	if (old_vc4_state->dlist_count != new_vc4_state->dlist_count ||
+	    old_vc4_state->pos0_offset != new_vc4_state->pos0_offset ||
+	    old_vc4_state->pos2_offset != new_vc4_state->pos2_offset ||
+	    old_vc4_state->ptr0_offset != new_vc4_state->ptr0_offset ||
+	    vc4_lbm_size(plane->state) != vc4_lbm_size(state))
 		return -EINVAL;
 
+	/* Only pos0, pos2 and ptr0 DWORDS can be updated in an async update
+	 * if anything else has changed, fallback to a sync update.
+	 */
+	for (i = 0; i < new_vc4_state->dlist_count; i++) {
+		if (i == new_vc4_state->pos0_offset ||
+		    i == new_vc4_state->pos2_offset ||
+		    i == new_vc4_state->ptr0_offset ||
+		    (new_vc4_state->lbm_offset &&
+		     i == new_vc4_state->lbm_offset))
+			continue;
+
+		if (new_vc4_state->dlist[i] != old_vc4_state->dlist[i])
+			return -EINVAL;
+	}
+
 	return 0;
 }