drm: sti: enable auxiliary CRTC

For stih407 SoC enable the second mixer to get two CRTC.
Allow GPD planes and encoders to be connected to this new CRTC.
Cursor plane can only be set on first CRTC.
GPD clocks needed change the parent clock depending on which
CRTC GPD are used.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>

drivers/gpu/drm/sti/sti_gdp.c

@@ -83,6 +83,8 @@ struct sti_gdp_node_list {
  *
  * @layer:		layer structure
  * @clk_pix:            pixel clock for the current gdp
+ * @clk_main_parent:    gdp parent clock if main path used
+ * @clk_aux_parent:     gdp parent clock if aux path used
  * @vtg_field_nb:       callback for VTG FIELD (top or bottom) notification
  * @is_curr_top:        true if the current node processed is the top field
  * @node_list:		array of node list
@@ -90,6 +92,8 @@ struct sti_gdp_node_list {
 struct sti_gdp {
 	struct sti_layer layer;
 	struct clk *clk_pix;
+	struct clk *clk_main_parent;
+	struct clk *clk_aux_parent;
 	struct notifier_block vtg_field_nb;
 	bool is_curr_top;
 	struct sti_gdp_node_list node_list[GDP_NODE_NB_BANK];
@@ -307,6 +311,17 @@ static int sti_gdp_prepare_layer(struct sti_layer *layer, bool first_prepare)
 
 		/* Set and enable gdp clock */
 		if (gdp->clk_pix) {
+			struct clk *clkp;
+			/* According to the mixer used, the gdp pixel clock
+			 * should have a different parent clock. */
+			if (layer->mixer_id == STI_MIXER_MAIN)
+				clkp = gdp->clk_main_parent;
+			else
+				clkp = gdp->clk_aux_parent;
+
+			if (clkp)
+				clk_set_parent(gdp->clk_pix, clkp);
+
 			res = clk_set_rate(gdp->clk_pix, rate);
 			if (res < 0) {
 				DRM_ERROR("Cannot set rate (%dHz) for gdp\n",
@@ -521,6 +536,14 @@ static void sti_gdp_init(struct sti_layer *layer)
 		gdp->clk_pix = devm_clk_get(layer->dev, clk_name);
 		if (IS_ERR(gdp->clk_pix))
 			DRM_ERROR("Cannot get %s clock\n", clk_name);
+
+		gdp->clk_main_parent = devm_clk_get(layer->dev, "main_parent");
+		if (IS_ERR(gdp->clk_main_parent))
+			DRM_ERROR("Cannot get main_parent clock\n");
+
+		gdp->clk_aux_parent = devm_clk_get(layer->dev, "aux_parent");
+		if (IS_ERR(gdp->clk_aux_parent))
+			DRM_ERROR("Cannot get aux_parent clock\n");
 	}
 }