drm/sti: fix dynamic z-ordering

Apply the plane depth when the plane is updated.
If the depth is different from the previous plane update,
the register controlling the plane depth is cleaned and updated
with the new depth.

Signed-off-by: Vincent Abriou <vincent.abriou@st.com>
Reviewed-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>

1 files changed, 14 insertions, 5 deletions

diff --git a/drivers/gpu/drm/sti/sti_mixer.c b/drivers/gpu/drm/sti/sti_mixer.c
index 13a4b84deab6..61a2048cf5d6 100644
--- a/drivers/gpu/drm/sti/sti_mixer.c
+++ b/drivers/gpu/drm/sti/sti_mixer.c
@@ -103,10 +103,11 @@ static void sti_mixer_set_background_area(struct sti_mixer *mixer,
 
 int sti_mixer_set_layer_depth(struct sti_mixer *mixer, struct sti_layer *layer)
 {
-	int layer_id = 0, depth = layer->zorder;
+	int layer_id, depth = layer->zorder;
+	unsigned int i;
 	u32 mask, val;
 
-	if (depth >= GAM_MIXER_NB_DEPTH_LEVEL)
+	if ((depth < 1) || (depth > GAM_MIXER_NB_DEPTH_LEVEL))
 		return 1;
 
 	switch (layer->desc) {
@@ -136,15 +137,23 @@ int sti_mixer_set_layer_depth(struct sti_mixer *mixer, struct sti_layer *layer)
 		DRM_ERROR("Unknown layer %d\n", layer->desc);
 		return 1;
 	}
-	mask = GAM_DEPTH_MASK_ID << (3 * depth);
-	layer_id = layer_id << (3 * depth);
+
+	/* Search if a previous depth was already assigned to the layer */
+	val = sti_mixer_reg_read(mixer, GAM_MIXER_CRB);
+	for (i = 0; i < GAM_MIXER_NB_DEPTH_LEVEL; i++) {
+		mask = GAM_DEPTH_MASK_ID << (3 * i);
+		if ((val & mask) == layer_id << (3 * i))
+			break;
+	}
+
+	mask |= GAM_DEPTH_MASK_ID << (3 * (depth - 1));
+	layer_id = layer_id << (3 * (depth - 1));
 
 	DRM_DEBUG_DRIVER("%s %s depth=%d\n", sti_mixer_to_str(mixer),
 			 sti_layer_to_str(layer), depth);
 	dev_dbg(mixer->dev, "GAM_MIXER_CRB val 0x%x mask 0x%x\n",
 		layer_id, mask);
 
-	val = sti_mixer_reg_read(mixer, GAM_MIXER_CRB);
 	val &= ~mask;
 	val |= layer_id;
 	sti_mixer_reg_write(mixer, GAM_MIXER_CRB, val);